Wrenching Douglas-fir seedlings in August: immediate but no lasting effects.

Treesearch

William I. Stein

1984-01-01

Effects of wrenching Douglas-fir seedlings in August of their second season in the D. L. Phipps State Forest Nursery, Elkton, Oregon, were determined by periodic samplings to learn of changes in phenological, morphological, and growth characteristics. Initial effects of wrenching moderated by January when seedlings were lifted; both wrenched and unwrenched seedlings...

Characterization biometric and morphophysiological of Peach rootstock seeds using images of their seedling vigor.

PubMed

Souza, Aline Das Graças; Smiderle, Oscar Jose; Bianchi, Valmor Joao

2018-04-26

This study aimed to evaluate the efficiency of using the computerized imaging seed analysis system (SAS) in the biometric and morphophysiological characterization of seeds and the initial growth of seedlings from peach rootstocks. The experimental design was completely randomized with five replicates of 20 seeds. The variables analyzed were degree of seed humidity, length and width of seeds measured by SAS technology and manual measurements, mean germination time, germination percentage, radicle length and width, taproot length, length of the aerial part and taproot/aerial part ratio. The highest seed length, germination percentage (100%) and lower germination time (11.3), were obtained with the cv. Capdeboscq while, 'Tsukuba 1', 2' and 3' had intermediate seedlings length, varying from 1.55 to 1.65 cm with mean germination times between 14.5 and 18.0 days and average germination percentage of 96%. The computerized analysis of images is fast and efficient for biometric evaluations such as seed width and length, as well as initial growth of peach tree seedlings. The cvs Capdeboscq, Flordaguard and Tsukuba 2 presented greater radicle width, length and a mean taproot/aerial part ratio equal to 2, as well as higher number of adventitious roots, which indicated a strong positive correlation between radicle length, taproot length and initial seedling growth. The continuity of the research will certainly allow the development of reliable procedures for other species, besides allowing the identification of wider alternatives for the use of this system for the expansion of knowledge in the areas of physiology and evaluation of the physiological potential of seeds. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Factors Affecting Seedling Survivorship of Blue Oak (Quercus douglasii H. & A.) in Central California

Treesearch

Frank W. Davis; Mark Borchert; L. E. Harvey; Joel C. Michaelsen

1991-01-01

Blue oak seedling mortality was studied in relation to vertebrate predators, initial acorn planting position, slope and aspect, and oak canopy cover at two sites in the Central Coast Ranges of California. Seedling survival rates (Psd) were related to treatment variables using logistic regression analysis. Analysis of 2842 seedlings for 3 years following establishment...

Seedling Disease Survey in Michigan

USDA-ARS?s Scientific Manuscript database

Stand establishment and persistence continue to be problems for Michigan growers. To determine the extent and severity of the problem, a survey of diseased seedlings from Michigan fields was initiated in 2008. Samples were collected of diseased seedlings for two years. In 2008, samples were collecte...

Small Changes in the Regulation of One Arabidopsis Profilin Isovariant, PRF1, Alter Seedling Development

PubMed Central

McKinney, Elizabeth Cohen; Kandasamy, Muthugapatti K.; Meagher, Richard B.

2001-01-01

Profilin (PRF) is a low-molecular-weight actin binding protein encoded by a diverse gene family in plants. Arabidopsis PRF1 transcripts are moderately well expressed in all vegetative organs. A regulatory mutant in PRF1, prf1-1, was isolated from a library of T-DNA insertions. The insertion disrupted the promoter region of PRF1 100 bp upstream from the transcriptional start site. Although steady state levels of PRF1 transcripts appeared normal in mature prf1-1 plants, the levels in young seedlings were only one-half those observed in wild type. Reactions with a PRF1 isovariant–specific monoclonal antiserum and general anti-profilin antisera demonstrated that PRF1 protein levels also were one-half those found in wild-type seedlings, although total profilin levels were unaffected. Mutant seedlings no longer could downregulate PRF1 levels in the light, as did wild type. Consistent with their molecular phenotypes, young mutant seedlings displayed several morphological phenotypes but developed into apparently normal adult plants. Their initial germination rate and development were slow, and they produced excessive numbers of root hairs. Mutant seedlings had abnormally raised cotyledons, elongated hypocotyls, and elongated cells in the hypocotyl, typical of phenotypes associated with some defects in light and circadian responses. A wild-type PRF1 transgene fully complements the hypocotyl phenotypes in the prf1-1 mutant. The ability of profilin to regulate actin polymerization and participate directly in signal transduction pathways is discussed in light of the prf1-1 phenotypes. PMID:11340190

Allelopathic and bioherbicidal potential of Cladonia verticillaris on the germination and growth of Lactuca sativa.

PubMed

Tigre, R C; Silva, N H; Santos, M G; Honda, N K; Falcão, E P S; Pereira, E C

2012-10-01

Responses to germination and initial growth of Lactuca sativa (lettuce) submitted to organic extracts and purified compounds of Cladonia verticillaris ("salambaia") were analyzed in this work. The experiments were conducted in laboratory conditions using extracts and pure compounds at different concentrations. None of the assays showed any influence on the germination of L. sativa seeds using C. verticillaris extracts; however, modifications in leaf area and seedling hypocotyl and root development occurred. In the growth experiments, seedlings exposed to ether or acetone extract showed diminished hypocotyl growth in detriment to the root stimulus, compared to controls. Increases in extract concentrations led to the formation of abnormal seedlings. To determine the allelochemicals of C. verticillaris, its principal components, fumarprotocetraric and protocetraric acids, were isolated and then analyzed by high performance liquid chromatography (HPLC). When the seedlings were exposed to the two acids separately, presented increased leaf area at all concentrations. In contrast, hypocotyl and root stimulus was observed only in the presence of protocetraric acid at different concentrations. Fumarprotocetraric as well as protocetraric acids, isolated and purified from C. verticillaris and Parmotrema dilatatum respectively, influenced the development of L. sativa seedlings at high concentrations, indicating a possible bioherbicide potential of these acids. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

The effects of pruning treatments and initial seedling morphology on northern red oak seedling growth

Treesearch

Donald J. Kaczmarek; Phillip E. Pope

1993-01-01

Northern red oak (Quercus rubra L.) seedlings exhibit relatively high survival rates following planting, but their growth rates are often slow and extensive stem dieback can occur. This study was designed to investigate the growth responses of northern red oak seedlings planted with or without root-pruning or shoot-pruning. One-year-old (1-0) northern red oak nursery...

The effects of moose (Alces alces L.) on hemlock (Tsuga canadensis (L.) Carr.) seedling establishment in Algonquin Provincial Park, Ontario, Canada

Treesearch

S. A. Vasiliauskas; L. W. Aarssen

2000-01-01

The effects of moose on eastern hemlock (Tsuga canadensis) natural seedling establishment in Algonquin Provincial Park, Ontario, were examined. Two thousand seedlings were tagged on 56 sites in 1992 and monitored for six years. Initial data collected included seedling height, browsing history and percent crown closure. At the end of the growing...

Economic rationale for planting less trees in the face of seedling mortality

Treesearch

Thomas J. Dean; S. Joseph Chang

2002-01-01

Simple economic analyses are used to demonstrate that planting extra trees to compensate for initial seedling mortality can actually reduce the profit expected from a pine plantation. At a 6-percent interest rate, the cost of planting 15 or 25 percent additional seedlings compounded to the end of a 30-year rotation exceeds the revenue lost to these rates of seedling...

Effects of glucose and ethylene on root hair initiation and elongation in lettuce (Lactuca sativa L.) seedlings.

PubMed

Harigaya, Wakana; Takahashi, Hidenori

2018-05-01

Root hair formation occurs in lettuce seedlings after transfer to an acidic medium (pH 4.0). This process requires cortical microtubule (CMT) randomization in root epidermal cells and the plant hormone ethylene. We investigated the interaction between ethylene and glucose, a new signaling molecule in plants, in lettuce root development, with an emphasis on root hair formation. Dark-grown seedlings were used to exclude the effect of photosynthetically produced glucose. In the dark, neither root hair formation nor the CMT randomization preceding it occurred, even after transfer to the acidic medium (pH 4.0). Adding 1-aminocyclopropane-1-carboxylic-acid (ACC) to the medium rescued the induction, while adding glucose did not. Although CMT randomization occurred when glucose was applied together with ACC, it was somewhat suppressed compared to that in ACC-treated seedlings. This was not due to a decrease in the speed of randomization, but due to lowering of the maximum degree of randomization. Despite the negative effect of glucose on ACC-induced CMT randomization, the density and length of ACC-induced root hairs increased when glucose was also added. The hair-cell length of the ACC-treated seedlings was comparable to that in the combined-treatment seedlings, indicating that the increase in hair density caused by glucose results from an increase in the root hair number. Furthermore, quantitative RT-PCR revealed that glucose suppressed ethylene signaling. These results suggest that glucose has a negative and positive effect on the earlier and later stages of root hair formation, respectively, and that the promotion of the initiation and elongation of root hairs by glucose may be mediated in an ethylene-independent manner.

Establishing native grasses in a big sagebrush-dominated site: an intermediate restoration step

USGS Publications Warehouse

Huber-Sannwald, Elisabeth; Pyke, David A.

2005-01-01

Many semiarid rangelands in the Great Basin, U.S.A., are shifting dominance to woody species as a consequence of land degradation including intense livestock grazing and fire suppression. Whereas past rehabilitation efforts in Big sagebrush (Artemisia tridentata) steppes removed the shrub and added introduced forage grasses to successfully shift communities from shrublands to grasslands, current consensus is that native species should be included in restoration projects and that retention of some woody plants is desirable. We examined the potential for interseeding grasses into dense shrub communities as a precursor to thinning shrubs and releasing grasses from shrub interference. We compared seedling establishment of the native grass, Bluebunch wheatgrass (Pseudoroegneria spicata), with that of the Eurasia grass, Crested wheatgrass (Agropyron desertorum), in dense Ar. tridentata stands. Shrubs may play an important role as nurse plants for seedling establishment (reduced solar radiation, 'island of fertility' effect) but result in highly contrasting light environments and root interference for seedlings. In experimental plots, we examined effects of Ar. tridentata shade levels (0, 40, 70, and 90% reduction of solar radiation) and initial root exclusion (present/absent) on the establishment and growth of P. spicata and Ag. desertorum seedlings. With this design we evaluated the interference effects of Ar. tridentata on the two grasses and identified the most beneficial microsites for grass restoration in Ar. tridentataa??dominated communities. We predicted seedling survival and growth to be greater under moderate shade (40% reduction) and limited root competition than under no or strong shade conditions (0 and 90%) and unrestricted root interactions. Fifty to 85% of the P. spicata and Ag. desertorum seedlings survived the dry summer months of 1995 and 1996 and the intervening winter. Neither shading nor root exclusion from Ar. tridentata affected final seedling survival of either species. Seedling biomass of both grass species was negatively affected by initial root interactions with Ar. tridentata. However, the analysis of seedling biomass variability (coefficient of variation) indicated that in all shade and root-exclusion treatments, some seedlings of both species developed to large individuals to survive in Ar. tridentataa??dominated rangelands. Thus, the use of interseeding techniques shows promise for restoring herbaceous species in dense Ar. tridentata stands and should be given further consideration when shrub retention is an important consideration.

Establishment of Swamp Tupelo Seedlings After Regeneration Cuts

Treesearch

Dean S. DeBell; J. Dennis Auld

1971-01-01

Environmental factors influencing natural regeneration of swamp tupelo were examined in a study involving five harvest treatments replicated in 3 successive years. Initial seedling establishment was related to seed production, but other factors probably are more limiting in most years. Abundance of established seedlings differed significantly with harvest cuttings,...

Effect of initial seedling size, understory competition, and overstory density on the survival and growth of Pinus echinata seedlings underplanted in hardwood forests for restoration

Treesearch

John M. Kabrick; Benjamin O. Knapp; Daniel C. Dey; David R. Larsen

2015-01-01

There is interest in restoring shortleaf pine (Pinus echinata) in pine–oak woodlands where it once was abundant. Because of its shade intolerance and slow initial growth rate, shortleaf pine restoration has remained a challenge because competition from hardwoods exhibits greater initial growth following canopy removal but greater shade tolerance with...

Seedling establishment and physiological responses to temporal and spatial soil moisture changes

Treesearch

Jeremy Pinto; John D. Marshall; Kas Dumroese; Anthony S. Davis; Douglas R. Cobos

2016-01-01

In many forests of the world, the summer season (temporal element) brings drought conditions causing low soil moisture in the upper soil profile (spatial element) - a potentially large barrier to seedling establishment. We evaluated the relationship between initial seedling root depth, temporal and spatial changes in soil moisture during drought after...

Germination and allometry of the native palm tree Euterpe edulis compared to the introduced E. oleracea and their hybrids in Atlantic rainforest.

PubMed

Tiberio, F C S; Sampaio-e-Silva, T A; Dodonov, P; Garcia, V A; Silva Matos, D M

2012-11-01

Palms are distinctive plants of tropics and have peculiar allometric relations. Understanding such relations is useful in the case of introduced species because their ability to establish and invade must be clarified in terms of their responses in the new site. Our purpose was to assess the survival and invasive capacity of an introduced palm species in the Atlantic rainforest, Euterpe oleracea Mart., compared to the native Euterpe edulis Mart. and to the hybrids produced between the two species. Considering this, we compared the allometry in different ontogenetic stages, the germination rates, and aspects of the initial development. The ontogenetic stages proposed for both Euterpe illustrated the growth patterns described for palm trees. E. oleracea and hybrids adjusted to the geometric similarity allometric model, while E. edulis presented a slope greater than would be expected considering this model, indicating a greater height for a given diameter. E. oleracea showed the same amount of pulp per fruit as E. edulis and a similar initial development of seedlings. The main differences observed were a lower germination rate and a faster height gain of E. oleracea seedlings. We conclude that E. oleracea, which is similar to E. edulis in aspects of allometry, development, seed and seedling morphology, may be an important competitor of this native palm tree in the Atlantic Forest.

Photoprotection, photosynthesis and growth of tropical tree seedlings under near-ambient and strongly reduced solar ultraviolet-B radiation.

PubMed

Krause, G Heinrich; Jahns, Peter; Virgo, Aurelio; García, Milton; Aranda, Jorge; Wellmann, Eckard; Winter, Klaus

2007-10-01

Seedlings of two late-successional tropical rainforest tree species, Tetragastris panamensis (Engler) O. Kuntze and Calophyllum longifolium (Willd.), were field grown for 3-4 months at an open site near Panama City (9 degrees N), Panama, under plastic films that either transmitted or excluded most solar UV-B radiation. Experiments were designed to test whether leaves developing under bright sunlight with strongly reduced UV-B are capable of acclimating to near-ambient UV-B conditions. Leaves of T. panamensis that developed under near-ambient UV-B contained higher amounts of UV-absorbing substances than leaves of seedlings grown under reduced UV-B. Photosynthetic pigment composition, content of alpha-tocopherol, CO(2) assimilation, potential photosystem II (PSII) efficiency (evaluated by F(v)/F(m) ratios) and growth of T. panamensis and C. longifolium did not differ between seedlings developed under near-ambient and reduced solar UV-B. When seedlings were transferred from the reduced UV-B treatment to the near-ambient UV-B treatment, a pronounced inhibition of photosynthetic capacity was observed initially in both species. UV-B-mediated inhibition of photosynthetic capacity nearly fully recovered within 1 week of the transfer in C. longifolium, whereas in T. panamensis an about 35% reduced capacity of CO(2) uptake was maintained. A marked increase in UV-absorbing substances was observed in foliage of transferred T. panamensis seedlings. Both species exhibited enhanced mid-day photoinhibition of PSII immediately after being transferred from the reduced UV-B to the near-ambient UV-B treatment. This effect was fully reversible within 1d in T. panamensis and within a few days in C. longifolium. The data show that leaves of these tropical tree seedlings, when developing in full-spectrum sunlight, are effectively protected against high solar UV-B radiation. In contrast, leaves developing under conditions of low UV-B lacked sufficient UV protection. They experienced a decline in photosynthetic competence when suddenly exposed to near-ambient UV-B levels, but exhibited pronounced acclimative responses.

Ontogenetic patterns of CO sub 2 exchange of Quercus rubra L. leaves during three flushes of shoot growth I. median flush leaves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, P.J.; Isebrands, J.G.; Dickson, R.E.

1988-03-01

Oak (Quercus) seedlings exhibit a pattern of shoot growth known to place demands on carbohydrate and nutrient reserves. This study was designed to determine ontogenetic patterns in CO{sub 2} exchanges properties of red oak leaves, and to determine if individual leaf CO{sub 2} exchange rates (CER) increase in response to the assimilate demand placed on a seedling during flushing. Northern red oak (Q. rubra L.) seedlings were grown in environments favorable for multiple flushes of shoot growth. Measurements of CER on single, attached, median leaves from each flush were made over a range of photosynthetic photon flux densities on plantsmore » at nine stages of seedling development through three flushes of growth. Carbon dioxide exchange rate of red oak leaves increased during leaf development up to and beyond full leaf expansion before decreasing an unusual pattern of photosynthesis during leaf ontogeny. Furthermore, first- and second-flush leaf CER initially decreased and then increased in conjunction with the third flush of shoot growth. These patterns indicate that red oak leaves have a capacity for CER adjustment in response to increase sink demand.« less

Influence of family and nitrogen fertilizer on growth and nutrition of western hemlock seedlings.

Treesearch

M.A. Radwan; D.S. DeBell; J.E. Wilcox

1990-01-01

Effects of genotype and nitrogen fertilizer on growth and shoot nutrients of western hemlock seedlings were determined by using 11 open-pollinated families from coastal Oregon and Washington. The families differed significantly in growth, initially and after one growing season after treatment. All seedlings responded well to fertilizer, and fertilization significantly...

Ten-year growth comparison between rooted cuttings and seedlings of loblolly pine

Treesearch

H.E. Stelzer; G. Sam Foster; D.V. Shaw; J.B. McRae

1997-01-01

Rooted cuttings and seedlings of loblolly pine (Pinus taeda L.) were established in a central Alabama field trial. Five, full-sib families, with an average number of six clones per family, were evaluated. Mean cutting/seedling height ratios revealed that despite initial differences in size, relative growth rates of both propagule types stabilized and...

Underplanting cherrybark oak (Quercus pagoda Raf.) seedlings on a bottomland site in the southern United States

Treesearch

Emile S. Gardiner; Jimmie L. Yeiser

2006-01-01

We initiated a study on a bottomland site in the southern United States to examine the effects of Japanese honeysuckle (Lonicera japonica Thunberg) control and seedlings of two root classes on survival and growth of underplanted cherrybark oak (Quercus pagoda Raf.) seedlings. Three honeysuckle control treatments were assigned to...

Mosaic Stunting in jack pine seedlings in a northern Michigan bareroot nursery

Treesearch

Lynette Potvin; R. Kasten Dumroese; Martin F. Jurgensen; Dana Richter

2010-01-01

Mosaic, or patchy, stunting of bareroot conifer seedlings is thought to be caused by deficiencies of mycorrhizal fungi following fumigation, resulting in reduced nutrient uptake, particularly phosphorus. Mosaic stunting of jack pine (Pinus banksiana) seedlings was observed in 2005 at the USDA Forest Service JW Toumey Nursery in Watersmeet, MI. We initiated a study to...

Nursery response of Acacia koa seedlings to container size, irrigation method, and fertilization rate

Treesearch

R. Kasten Dumroese; Anthony S. Davis; Douglass F. Jacobs

2011-01-01

Planting koa (Acacia koa A. Gray) in Hawai'i, USA aids in restoration of disturbed sites essential to conservation of endemic species. Survival and growth of planted seedlings under vegetative competition typically increases with initial plant size. Increasing container size and fertilizer rate may produce larger seedlings, but high fertilization can lead to...

Variation in flood tolerance of container-grown seedlings of swamp white oak, bur oak, and white oak

Treesearch

Michael P. Walsh; J.W. Van Sambeek; Mark V. Coggeshall

2008-01-01

How much variation in flood tolerance exists among seedlings within oak species, given the flood frequency of sites from which acorns are collected, has been largely unexplored. Our studies examined initial growth and flood tolerance for seedlings of swamp white oak (Quercus bicolor Willd.), bur oak (Q. macrocarpa L.), and white...

Perennial grasses reduce woody plant seedlings...on mixed conifer fuel-break

Treesearch

Harry E. Schimke Lisle R. Green Danny Heavilin

1970-01-01

After initial clearing, parts of a fuelbreak on the Stanislaus Nationd Forest, central California, were planted to perennial grasses; other parts were not. After 5 years, a comparison between adjacent seeded sand unseeded strips shows that the perernnials had reduced the number of woody plant seedlings by a factor of 8, height of seedlings by 50 percent, and amount of...

Lab and Field Warming Similarly Advance Germination Date and Limit Germination Rate for High and Low Elevation Provenances of Two Widespread Subalpine Conifers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kueppers, Lara; Faist, Akasha; Ferrenberg, Scott

Accurately predicting upslope shifts in subalpine tree ranges with warming requires understanding how future forest populations will be affected by climate change, as these are the seed sources for new tree line and alpine populations. Early life history stages are particularly sensitive to climate and are also influenced by genetic variation among populations. Here, we tested the climate sensitivity of germination and initial development for two widely distributed subalpine conifers, using controlled-environment growth chambers with one temperature regime from subalpine forest in the Colorado Rocky Mountains and one 5 °C warmer, and two soil moisture levels. We also tracked germinationmore » rate and timing, rate of seedling development, and seedling morphology for two seed provenances separated by ~300 m elevation. Warming advanced germination timing and initial seedling development by a total of ~2 weeks, advances comparable to mean differences between provenances. Advances were similar for both provenances and species; however, warming reduced the overall germination rate, as did low soil moisture, only for Picea engelmannii. A three-year field warming and watering experiment planted with the same species and provenances yielded responses qualitatively consistent with the lab trials. Altogether these experiments indicate that in a warmer, drier climate, P. engelmannii germination, and thus regeneration, could decline, which could lead to declining subalpine forest populations, while Pinus flexilis forest populations could remain robust as a seed source for upslope range shifts.« less

Lab and Field Warming Similarly Advance Germination Date and Limit Germination Rate for High and Low Elevation Provenances of Two Widespread Subalpine Conifers

DOE PAGES

Kueppers, Lara; Faist, Akasha; Ferrenberg, Scott; ...

2017-11-11

Accurately predicting upslope shifts in subalpine tree ranges with warming requires understanding how future forest populations will be affected by climate change, as these are the seed sources for new tree line and alpine populations. Early life history stages are particularly sensitive to climate and are also influenced by genetic variation among populations. Here, we tested the climate sensitivity of germination and initial development for two widely distributed subalpine conifers, using controlled-environment growth chambers with one temperature regime from subalpine forest in the Colorado Rocky Mountains and one 5 °C warmer, and two soil moisture levels. We also tracked germinationmore » rate and timing, rate of seedling development, and seedling morphology for two seed provenances separated by ~300 m elevation. Warming advanced germination timing and initial seedling development by a total of ~2 weeks, advances comparable to mean differences between provenances. Advances were similar for both provenances and species; however, warming reduced the overall germination rate, as did low soil moisture, only for Picea engelmannii. A three-year field warming and watering experiment planted with the same species and provenances yielded responses qualitatively consistent with the lab trials. Altogether these experiments indicate that in a warmer, drier climate, P. engelmannii germination, and thus regeneration, could decline, which could lead to declining subalpine forest populations, while Pinus flexilis forest populations could remain robust as a seed source for upslope range shifts.« less

Quantitative trait loci associated with phenological development, low temperature tolerance, grain quality, and agronomic characters in wheat (Triticum aestivum L.)

USDA-ARS?s Scientific Manuscript database

Plants must respond to environmental cues and schedule their development in order to react to periods of abiotic stress and commit fully to growth and reproduction under favorable conditions. This study was initiated to identify SNP markers for characters expressed from the seedling stage to plant m...

DNA Damage Levels Determine Cyclobutyl Pyrimidine Dimer Repair Mechanisms in Alfalfa Seedlings.

PubMed Central

Quaite, F. E.; Takayanagi, S.; Ruffini, J.; Sutherland, J. C.; Sutherland, B. M.

1994-01-01

Ultraviolet radiation in sunlight damages DNA in plants, but little is understood about the types, lesion capacity, and coordination of repair pathways. We challenged intact alfalfa seedlings with UV doses that induced different initial levels of cyclobutyl pyrimidine dimers and measured repair by excision and photoreactivation. By using alkaline gel electrophoresis of nonradioactive DNAs treated with a cyclobutyl pyrimidine dimer-specific UV endonuclease, we quantitated ethidium-stained DNA by electronic imaging and calculated lesion frequencies from the number average molecular lengths. At low initial dimer frequencies (less than ~30 dimers per million bases), the seedlings used only photoreactivation to repair dimers; excision repair was not significant. At higher damage levels, both excision and photorepair contributed significantly. This strategy would allow plants with low damage levels to use error-free repair requiring only an external light energy source, whereas seedlings subjected to higher damage frequencies could call on additional repair processes requiring cellular energy. Characterization of repair in plants thus requires an investigation of a range of conditions, including the level of initial damage. PMID:12244228

Implications of seed size for seedling survival in Carnegiea gigantea and Ferocactus wislizeni (Cactaceae)

USGS Publications Warehouse

Bowers, Janice E.; Pierson, E.A.

2001-01-01

Larger seeds have been shown to convey benefits for seedling survival but the mechanisms of this process are not well understood. In this study, seed size and seedling survival were compared for 2 sympatric cactus species, Carnegiea gigantea (Engelm.) Britt. & Rose and Ferocactus wislizeni (Engelm.) Britt. & Rose, in laboratory and field experiments in the northern Sonoran Desert. Both species have small seeds, but Ferocactus seeds are nearly twice as long and 3 times as heavy as those of Carnegiea. The difference in size is perpetuated after germination: new Ferocactus seedlings have 4 times the estimated volume of new Carnegiea seedlings. In an outdoor experiment, annual survivorship of both species was low but was 6 times higher for Ferocactus (6 seedlings, 8.1%) than Carnegiea (1 seedling, 1.4%). The pattern of seedling mortality in relation to temperature and rain suggests that, after the initial flush of seed and seedling predation, drought and heat took a greater toll on Carnegiea than Ferocactus seedlings, probably because the larger seedling volume of Ferocactus conferred greater drought tolerance. In addition, F. wislizeni could become established without benefit of nurse plants whereas C. gigantea could not; this might reflect differential tolerance to high soil temperatures.

Acclimation responses to high light by Guazuma ulmifolia Lam. (Malvaceae) leaves at different stages of development.

PubMed

Calzavara, A K; Rocha, J S; Lourenço, G; Sanada, K; Medri, C; Bianchini, E; Pimenta, J A; Stolf-Moreira, R; Oliveira, H C

2017-09-01

The re-composition of deforested environments requires the prior acclimation of seedlings to full sun in nurseries. Seedlings can overcome excess light either through the acclimation of pre-existing fully expanded leaves or through the development of new leaves that are acclimated to the new light environment. Here, we compared the acclimation capacity of mature (MatL, fully expanded at the time of transfer) and newly expanded (NewL, expanded after the light shift) leaves of Guazuma ulmifolia Lam. (Malvaceae) seedlings to high light. The seedlings were initially grown under shade and then transferred to full sunlight. MatL and NewL were used for chlorophyll fluorescence and gas exchange analyses, pigment extraction and morpho-anatomical measurements. After the transfer of seedlings to full sun, the MatL persisted and acclimated to some extent to the new light condition, since they underwent alterations in some morpho-physiological traits and maintained a functional electron transport chain and positive net photosynthesis rate. However, long-term exposure to high light led to chronic photoinhibition in MatL, which could be related to the limited plasticity of leaf morpho-anatomical attributes. However, the NewL showed a high capacity to use the absorbed energy in photochemistry and dissipate excess energy harmlessly, attributes that were favoured by the high structural plasticity exhibited by these leaves. Both the maintenance of mature, photosynthetically active leaves and the production of new leaves with a high capacity to cope with excess energy were important for acclimation of G. ulmifolia seedlings. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.

Chlorophyll, Carotenoid and Anthocyanin Accumulation in Mung Bean Seedling Under Clinorotation

NASA Astrophysics Data System (ADS)

Nakajima, Shusaku; Shiraga, Keiichiro; Suzuki, Tetsuhito; Kondo, Naoshi; Ogawa, Yuichi

2017-12-01

The accumulation of plant pigments in mung bean ( Vigna radiata L.) seedlings was measured after clinorotation (2 rpm for 2-4 days), and compared to a stationary control. The pigments measured included chlorophyll and carotenoid in primary leaves, and the anthocyanin in seedlings. While significant changes in chlorophyll and carotenoid accumulation were not observed during the initial 2 to 4 days of cultivation, by day 4 the seedlings grown on the clinostat had lower levels of anthocyanin, compared to those in the control seedlings. To further detail the cause for the observed reduction in anthocyanin accumulation under altered gravity conditions, seedlings were grown in the presence of silver nitrate, a known ethylene inhibitor, for 4 days, since it is known ethylene has a negative impact on anthocyanin accumulation. Silver nitrate promoted anthocyanin accumulation in the clinostat seedlings, and as a result there was no significant difference between the control and clinostat seedlings in anthocyanin accumulation. The results suggest that slow clinorotation negatively impacts anthocyanin pigmentation in mung bean seedlings, with endogenous ethylene suspected to be involved in this.

Seed-vectored endophytic bacteria modulate development of rice seedlings.

PubMed

Verma, S K; Kingsley, K; Irizarry, I; Bergen, M; Kharwar, R N; White, J F

2017-06-01

The aim of the present study was to evaluate the effects of the removal of indigenous bacteria from rice seeds on seedling growth and development. Here we report the presence of three indigenous endophytic bacteria in rice seeds that play important roles in modulating seedling development (shoot and root lengths, and formation of root hairs and secondary roots) and defence against pathogens. Seed-associated bacteria were removed using surface sterilization with NaOCl (bleach) followed by antibiotic treatment. When bacteria were absent, growth of seedlings in terms of root hair development and overall seedling size was less than that of seedlings that contained bacteria. Reactive oxygen staining of seedlings showed that endophytic bacteria became intracellular in root parenchyma cells and root hairs. Roots containing endophytic bacteria were seen to stain densely for reactive oxygen, while roots free of bacteria stained lightly for reactive oxygen. Bacteria were isolated and identified as Enterobacter asburiae (VWB1), Pantoea dispersa (VWB2) and Pseudomonas putida (VWB3) by 16S rDNA sequencing. Bacteria were found to produce indole acetic acid (auxins), inhibited the pathogen Fusarium oxysporum and solubilized phosphate. Reinoculation of bacteria onto seedlings derived from surface-disinfected rice and Bermuda grass seeds significantly restored seedling growth and development. Rice seeds harbour indigenous bacterial endophytes that greatly influence seedling growth and development, including root and shoot lengths, root hair formation and disease susceptibility of rice seedlings. This study shows that seeds of rice naturally harbour bacterial endophytes that play key roles in modulation of seedling development. © 2017 The Society for Applied Microbiology.

High frequency early in vitro flowering of Dendrobium Madame Thong-In (Orchidaceae).

PubMed

Sim, Guek Eng; Loh, Chiang Shiong; Goh, Chong Jin

2007-04-01

We have successfully developed a method to induce early in vitro flowering of the self-pollinated seedlings of a tropical orchid hybrid, Dendrobium Madame Thong-In. Transition of vegetative shoot apical meristem to inflorescence meristem was observed when young protocorms were cultured in modified KC liquid medium. In contrast, protocorms cultured on Gelrite-solidified medium only produced axillary shoots and roots. CW was required to trigger the transitional shoot apical meristem and BA enhanced inflorescence stalk initiation and flower bud formation. However, normal flower development was deformed in liquid medium but developed fully upon transferring to two-layered (liquid over Gelrite-solidified) medium. Under optimal condition, in vitro flowering was observed about 5 months after seed sowing. Segregation of flower colours was observed in these seedlings and seedpods formed upon artificial pollination of the in vitro flowers.

Field and laboratory root growth and development of Lesquerella germplasm

USDA-ARS?s Scientific Manuscript database

Lesquerella roots have not been fully characterized as compared to other crop species. There is initial information gathered on root trait variation in young seedling grown in laboratory settings but studies to determine if the results can be extrapolated in field grown plants are lacking. We report...

Indigenous endophytic seed bacteria promote seedling development and defend against fungal disease in browntop millet (Urochloa ramosa L.).

PubMed

Verma, S K; White, J F

2018-03-01

This study was conducted to investigate indigenous seed endophyte effects on browntop millet seedling development. We report that seed-inhabiting bacterial endophytes are responsible for promoting seedling development, including stimulation of root hair formation, increasing root and shoot length growth and increasing photosynthetic pigment content of seedlings. Bacterial endophytes also improved resistance of seedlings to disease. A total of four endophytic bacteria were isolated from surface-sterilized seeds and identified by 16S rDNA sequencing as Curtobacterium sp. (M1), Microbacterium sp. (M2), Methylobacterium sp. (M3) and Bacillus amyloliquefaciens (M4). Removal of bacteria with streptomycin treatment from the seeds compromised seedling growth and development. When endophytes were reinoculated onto seeds, seedlings recovered normal development. Strains M3 and M4 were found to be most potent in promoting growth of seedlings. Bacteria were found to produce auxin, solubilize phosphate and inhibit fungal pathogens. Significant protection of seedlings from Fusarium infection was found using strain M4 in microcosm assays. The antifungal lipopeptide genes for surfactin and iturin were detected in M4; culture extracts of M4 showed a positive drop collapse result for surfactins. This study demonstrates that browntop millet seeds vector indigenous endophytes that are responsible for modulation of seedling development and protection of seedlings from fungal disease. This study is significant and original in that it is the first report of seed-inhabiting endophytes of browntop millet that influence seedling development and function in defence against soilborne pathogens. This study suggests that conservation and management of seed-vectored endophytes may be important in development of more sustainable agricultural practices. © 2017 The Society for Applied Microbiology.

Development of a mixed shrub–ponderosa pine community in a natural and treated condition

Treesearch

Philip M. McDonald; Gary O. Fiddler

1995-01-01

On a medium site in northern California, a mostly shrub community was treated by two manual release techniques and by two herbicides, to study its development in both a natural (control) and treated condition. Survival and growth of planted ponderosa pine seedlings were quantified for 8 to 11 years after initial treatment applications. Treatments included manual...

Effect of ponderosa pine needle litter on grass seedling survival.

Treesearch

Burt R. McConnell; Justin G. Smith

1971-01-01

Hard fescue survival rates were followed for 6 years on four different pine needle treatment plots. Needle litter had a significant effect on initial survival of fescue seedlings, but subsequent losses undoubtedly resulted from the interaction of many factors.

Light-regulated and organ-specific expression of types 1, 2, and 3 light-harvesting complex b mRNAs in Ginkgo biloba.

PubMed Central

Chinn, E; Silverthorne, J; Hohtola, A

1995-01-01

In a prior study (E. Chinn and J. Silverthorne [1993] Plant Physiol 103: 727-732) we showed that the gymnosperm Ginkgo biloba was completely dependent on light for chlorophyll synthesis and chloroplast development and that expression of light-harvesting complex b (Lhcb) mRNAs was substantially increased by light. However, dark-grown seedlings that were transferred to constant white light took significantly longer than angiosperm seedlings to initiate a program of photomorphogenesis and the stems failed to green completely. We have prepared type-specific probes for mRNAs encoding major polypeptides of light-harvesting complex II (Lhcb1, Lhcb2, and Lhcb3) and have used these to analyze the expression of individual Lhcb mRNAs during greening. All three sequences accumulated in the top portions of dark-grown seedlings transferred to light, but, as was seen previously for total Lhcb mRNAs, there was a transient, reproducible decline in the levels of all three mRNAs after 4 d in the light. This transient decrease in Lhcb mRNA levels was not paralleled by a decrease in Chl accumulation. By contrast, there were significantly lower levels of all three Lhcb mRNAs in the lower portions of greening dark-grown stems as well as lower Chl levels. We conclude that although the tops of the plants have the capacity to etiolate and green, Gingko seedling stems continue a program of development into woody tissue in darkness that precludes greening when the seedlings are transferred to the light. PMID:7724674

Catechol, a major component of smoke, influences primary root growth and root hair elongation through reactive oxygen species-mediated redox signaling.

PubMed

Wang, Ming; Schoettner, Matthias; Xu, Shuqing; Paetz, Christian; Wilde, Julia; Baldwin, Ian T; Groten, Karin

2017-03-01

Nicotiana attenuata germinates from long-lived seedbanks in native soils after fires. Although smoke signals have been known to break seed dormancy, whether they also affect seedling establishment and root development remains unclear. In order to test this, seedlings were treated with smoke solutions. Seedlings responded in a dose-dependent manner with significantly increased primary root lengths, due mainly to longitudinal cell elongation, increased numbers of lateral roots and impaired root hair development. Bioassay-driven fractionations and NMR were used to identify catechol as the main active compound for the smoke-induced root phenotype. The transcriptome analysis revealed that mainly genes related to auxin biosynthesis and redox homeostasis were altered after catechol treatment. However, histochemical analyses of reactive oxygen species (ROS) and the inability of auxin applications to rescue the phenotype clearly indicated that highly localized changes in the root's redox-status, rather than in levels of auxin, are the primary effector. Moreover, H 2 O 2 application rescued the phenotype in a dose-dependent manner. Chemical cues in smoke not only initiate seed germination, but also influence seedling root growth; understanding how these cues work provides new insights into the molecular mechanisms by which plants adapt to post-fire environments. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Effect of various gases (methane, CO/sub 2/) on root development and/or mycorrhizae production on Virginia pine. [Pinus virginiana; Amanita rubescens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russo, V.M.; Klarman, W.L.

1975-01-01

Various flow rates of air, air containing methane, and air containing carbon dioxide were passed through sterile, nutrient-saturated sand in one-liter flasks. Sixteen-day-old axenic seedlings of Pinus virginiana were planted either prior to or immediately following treatment of medium. Some flasks were also inoculated with Amanita rubescens, a fungus commonly mycorrhizal with P. virginiana. Seedlings were maintained under continuous illumination for 30 days at 24 C and roots were then examined to determine development and/or mycorrhizal association. Dry weights of roots and whole seedlings were measured. Root development of seedlings planted in medium prior to treatment with air increased withmore » increase of flow-rate to 1.25 liters per hour. When treated with methane or carbon-dioxide fewer seedlings with developed root systems were produced. Seedlings planted in medium colonized by A. rubescens and treated with air or air containing carbon-dioxide produced increasing numbers of developed roots as flow rate increased, but other seedlings treated with methane produced fewer developed roots with increase in flow-rate. Mycorrhizal production was maximum at flow-rates between 0.25 and 0.6 liters. Generally fewer developed roots and/or mycorrhizae were produced by seedlings planted in treated medium than on similar seedlings planted before gas treatment. Dry weights generally paralleled root development.« less

Development of a Mixed-Shrub-Planted Ponderosa Pine Communicty on a Poor Site After Site Preparation and Release

Treesearch

Philip M. McDonald

2003-01-01

On a poor site in northern California, a mature brushfield was treated in various ways that left initial density categories of light, medium, and heavy shrubs. Density, foliar cover, and height of seven shrub species (alone and combined) and ponderosa pine seedlings in these categories were quantified from 1967 through 1978. Heretofore, density and development data for...

Characteristics of gaps and natural regeneration in mature longleaf pine flatwoods ecosystems

Treesearch

Jennifer L. Gagnon; Eric J. Jokela; W.K. Moser; Dudley A. Huber

2004-01-01

Developing uneven-aged structure in mature stands of longleaf pine requires scientifically based silvicultural systems that are reliable, productive and sustainable. Understanding seedling responses to varying levels of site resource availability within forest gaps is essential for effectively converting even-aged stands to uneven-aged stands. A project was initiated...

Lactarius deliciosus and Pinus radiata in New Zealand: towards the development of innovative gourmet mushroom orchards.

PubMed

Guerin-Laguette, Alexis; Cummings, Nicholas; Butler, Ruth Catherine; Willows, Anna; Hesom-Williams, Nina; Li, Shuhong; Wang, Yun

2014-10-01

The cultivation of Lactarius deliciosus (saffron milk cap) in New Zealand began in 2002 when fruiting bodies were produced in an Otago plantation of Pinus radiata seedlings artificially mycorrhized by L. deliciosus. In 2007, 42 P. radiata seedlings mycorrhized by L. deliciosus under controlled conditions were planted in a grass field at Plant and Food Research (Lincoln, Canterbury). The effects of pine bark mulch application and initial degree of mycorrhization of seedlings were examined to determine their influence on tree growth, development of mycorrhizae (i.e. their multiplication on the root system and their degree of branching) and fruiting body production. Mulch application increased tree growth significantly over 4 years. High initial mycorrhization slightly stimulated tree growth over 2 years. The initial degree of mycorrhization was positively, but not strongly, related to the persistence and development of L. deliciosus mycorrhizae and rhizomorphs based on root sample analyses 2 years after planting. However, mulching strongly reduced the proportion of highly branched L. deliciosus mycorrhizae compared with poorly ramified ones. A positive correlation was observed between the fruiting of L. deliciosus and the development of mycorrhizae. Mulching delayed the onset of fruiting body production. In 2010, fruiting bodies were produced only from non-mulched trees with eight of these (38 %) producing a total of 12 fruiting bodies. In 2011, 19 non-mulched trees (90 %) and 9 mulched trees (45 %) produced 143 and 47 fruiting bodies, respectively, totalling 190 fruiting bodies. By 2012, 19 non-mulched trees (90 %) and 13 mulched trees (65 %) produced 333 and 236 fruiting bodies, respectively, totalling 569 fruiting bodies (c. 30 kg). This study presents new information on factors influencing the onset of fruiting and the development of yields in a plantation of P. radiata mycorrhized by L. deliciosus. Projected yields as high as c. 300 kg/ha from the third year of production reiterate the feasibility of farming saffron milk cap in P. radiata plantations in New Zealand. Continued monitoring of this site and development of similar trials will provide important knowledge for the optimisation of yields in commercial saffron milk cap orchards.

Effect of vegetation management for reducing damage to lodgepole pine seedlings from northern pocket gophers

USGS Publications Warehouse

Engeman, Richard M.; Barnes, Victor G.; Anthony, Richard M.; Krupa, Heather W.

1997-01-01

The effects of vegetation management on northern pocket gopher (Thomomys talpoides) activity and damage to lodgepole pine (Pinus contorta) seedlings were studied using 2,4-D herbicide to alter the habitat. Treatments were applied to a large (8.1 ha) treatment unit and observed effects were compared with an untreated control unit of the same size. The greatly reduced forb and grass cover on the treated unit was associated with a corresponding decrease in pocket gopher activity that persisted for 6 years after initial treatment. Times until seedlings first incurred gopher damage and overall survival of seedlings were greatly increased on the treated unit.

Invasibility of a nutrient-poor pasture through resident and non-resident herbs is controlled by litter, gap size and propagule pressure.

PubMed

Eckstein, R Lutz; Ruch, Diana; Otte, Annette; Donath, Tobias W

2012-01-01

Since inference concerning the relative effects of propagule pressure, biotic interactions, site conditions and species traits on the invasibility of plant communities is limited, we carried out a field experiment to study the role of these factors for absolute and relative seedling emergence in three resident and three non-resident confamilial herb species on a nutrient-poor temperate pasture. We set up a factorial field experiment with two levels each of the factors litter cover (0 and 400 g m(-2)), gap size (0.01 and 0.1 m(2)) and propagule pressure (5 and 50 seeds) and documented soil temperature, soil water content and relative light availability. Recruitment was recorded in spring and autumn 2010 and in spring 2011 to cover initial seedling emergence, establishment after summer drought and final establishment after the first winter. Litter alleviated temperature and moisture conditions and had positive effects on proportional and absolute seedling emergence during all phases of recruitment. Large gaps presented competition-free space with high light availability but showed higher temperature amplitudes and lower soil moisture. Proportional and absolute seedling recruitment was significantly higher in large than in small gaps. In contrast, propagule pressure facilitated absolute seedling emergence but had no effects on proportional emergence or the chance for successful colonisation. Despite significantly higher initial seedling emergence of resident than non-resident species, seed mass and other species-specific traits may be better predictors for idiosyncratic variation in seedling establishment than status. Our data support the fluctuating resource hypothesis and demonstrate that the reserve effect of seeds may facilitate seedling emergence. The direct comparison of propagule pressure with other environmental factors showed that propagule pressure affects absolute seedling abundance, which may be crucial for species that depend on other individuals for sexual reproduction. However, propagule batch size did not significantly affect the chance for successful colonisation of disturbed plots.

Copper-Treated Containers Influence Root Development of Longleaf Pine Seedlings

Treesearch

James P. Barnett; John M. McGilvray

2002-01-01

Development of longleaf pine (Pinus palustris Mill.) seedlings grown in CopperblockTM containers and BC/ CFC First ChoiceTM Styrofoam blocks, with applications of Spin Out® root growth regulator, were compared to control seedlings. The copper treatments significantly changed seedling morphology; at...

Bacterial stimulation of adventitious rooting on in vitro cultured slash pine (Pinus elliottii Engelm.) seedling explants.

PubMed

Burns, J A; Schwarz, O J

1996-02-01

A bacterium has been isolated that initiates adventitious rooting when co-cultured under in vitro conditions with seedling-produced hypocotylary explants of slash pine (Pinus elliottii). Rooting efficiencies produced through bacterial-explant co-culture range from approximately 15% to greater than 90% over non-treated controls. Explant exposure to the root inducing bacterium has produced no obvious pathology in the regenerated plantlets. Seedling explants rooted by bacterial-explant co-culture have been successfully transitioned to ambient greenhouse conditions.

The effects of Vexar® seedling protectors on the growth and development of lodgepole pine roots

USGS Publications Warehouse

Engeman, Richard M.; Anthony, R. Michael; Krupa, Heather W.; Evans, James

1997-01-01

The effects on the growth and development of lodgepole pine roots from the Vexar® tubes used to protect seedlings from pocket gopher damage were studied in the Targhee National Forest, Idaho and the Deschutes National Forest, Oregon. At each site, Vexar-protected and unprotected seedlings, with and without above-ground gopher damage were examined after six growing seasons for root deformities and growth. Undamaged seedlings exhibited greater growth, reflecting the importance of non-lethal gopher damage as a deterrent to tree growth. Protected seedlings with similar damage history as unprotected seedlings had greater root depth than unprotected seedlings, although unprotected seedlings with no above-ground damage generally had the greatest root weight. In general, the percent of seedlings with root deformities was greater for the unprotected seedlings than for the Vexar-protectd seedlings, although this could be largely due to the greater care required to plant protected seedlings. Acute deformities were more common for unprotected seedlings, whereas root deformities with less severe bending were more common for protected seedlings. The incidence of crossed roots was similar for protected and unprotected seedlings on the Deschutes site, where enough occurrences of this deformity permitted analyses. Protected seedlings were similar in root abundance, root distribution, root size and vigor to the unprotected seedlings, with some indication from the Deshutes study site that root distribution was improved with Vexar protection.

Germination Under Stress: A Marker For Inherent Vigor Or An Isolated Event?

USDA-ARS?s Scientific Manuscript database

Seedling vigor and its translation to late-season vigor are, at best, murky for most beet breeders. The initial conditions a germinating seed encounters, and its ability to overcome them, affects stored energy reserves to withstand future adverse environments and the ability of the seedling to survi...

Seedling Vigor in Beta vulgaris: The Artistry of Germination

USDA-ARS?s Scientific Manuscript database

Seedling vigor and stand establishment are two problems that growers have struggled with for decades. The initial conditions that a germinating seed encounters, and its ability to deal with them, affect the rate at which germination occurs, the rate of mobilization of stored energy reserves that the...

Effects of nursery fertilizer and irrigation on ponderosa and lodgepole pine seedling size. Forest Service research note

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sloan, J.P.

1992-12-01

Eight fertilizer treatments combined with three irrigation regimes were used when growing lodgepole and ponderosa pine seedlings on two soil types at Lucky Peak Nursery near Biose, ID. Seedlings of both species were larger on the sandy loam than the clay loam soil. Milorganite, an organic fertilizer derived from sewage sludge, reduced initial seedbeed densities but had no further effects. Ammonium nitrate increased seedling size on the clay loam, but not on the sandy loam soil. Increased irrigation was more effective in increasing seedling size on the sandy loam than on the clay loam soil. However, ponderosa pine receiving themore » least irrigation in the nursery grew the fastest for 3 years after being transplanted in the field, possibly because of drought conditioning.« less

Efficiency of seed production in southern pine seed orchards

Treesearch

David L. Bramlett

1977-01-01

Seed production in southern pine seed orchards can be evaluated by estimating the efficiency of four separate stages of cone, seed, and seedling development. Calculated values are: cone efficiency (CE), the ratio of mature cones to the initial flower crop; seed efficiency (SE), the ratio of filled seeds per cone to the seed potential; extraction efficiency (EE), the...

FY18 SSC Agile-Seedling Fund Opportunities

NASA Technical Reports Server (NTRS)

Travis, Ramona

2017-01-01

The attached charts provide some background on an SSC (Stennis Space Center) initiative to support employees who may have ideas for technology development efforts but haven't been engaged in writing proposals to sources such as the Center Innovation Fund and other STMD (NASA Space Technology Mission Directorate) or HEOMD (NASA Human Exploration and Operations Mission Directorate) solicitation calls.

Density and rectangularity of planting influence 20-year growth and development of red alder.

Treesearch

Dean S. DeBell; Constance A. Harrington

2002-01-01

Red alder (Alnus rubra Bong.) seedlings were planted in northwestern Oregon, U.S.A., at five initial spacings: 0.6 × 1.2 m, 1.2 × 1.2 m, 1.2 × 1.8 m, 1.8 × 1.8 m, and 2.5 × 2.5 m. Up to about age 10, tree and stand characteristics were correlated primarily with initial planting density in the expected manner; through age 20, however, tree growth...

Experimental sand burial affects seedling survivorship, morphological traits, and biomass allocation of Ulmus pumila var. sabulosa in the Horqin Sandy Land, China

NASA Astrophysics Data System (ADS)

Tang, Jiao; Busso, Carlos Alberto; Jiang, Deming; Musa, Ala; Wu, Dafu; Wang, Yongcui; Miao, Chunping

2016-07-01

As a native tree species, Ulmus pumila var. sabulosa (sandy elm) is widely distributed in the Horqin Sandy Land, China. However, seedlings of this species have to withstand various depths of sand burial after emergence because of increasing soil degradation, which is mainly caused by overgrazing, climate change, and wind erosion. An experiment was conducted to evaluate the changes in its survivorship, morphological traits, and biomass allocation when seedlings were buried at different burial depths: unburied controls and seedlings buried vertically up to 33, 67, 100, or 133 % of their initial mean seedling height. The results showed that partial sand burial treatments (i.e., less than 67 % burial) did not reduce seedling survivorship, which still reached 100 %. However, seedling mortality increased when sand burial was equal to or greater than 100 %. In comparison with the control treatment, seedling height and stem diameter increased at least by 6 and 14 % with partial burial, respectively. In the meantime, seedling taproot length, total biomass, and relative mass growth rates were at least enhanced by 10, 15.6, and 27.6 %, respectively, with the partial sand burial treatment. Furthermore, sand burial decreased total leaf area and changed biomass allocation in seedlings, partitioning more biomass to aboveground organs (e.g., leaves) and less to belowground parts (roots). Complete sand burial after seedling emergence inhibited its re-emergence and growth, even leading to death. Our findings indicated that seedlings of sandy elm showed some resistance to partial sand burial and were adapted to sandy environments from an evolutionary perspective. The negative effect of excessive sand burial after seedling emergence might help in understanding failures in recruitments of sparse elm in the study region.

A spaceflight experiment to investigate the effects of a range of unilateral blue light phototropic stimulations on the movements of wheat coleoptiles (6-IML-1)

NASA Technical Reports Server (NTRS)

Heathcote, David G.

1992-01-01

In 1978, in response to an announcement of opportunity by NASA, two independent groups proposed related investigations to study the response of seedling plants to photostimulations at microgravity. The spaceflight experiment is known by its NASA acronym, FOTRAN. The scientific objectives behind the experiment are outlined, and a brief description of the spaceflight equipment and the experimental procedures developed to accomplish the aims of the experiment are presented. By reference to the results of ground-based studies, the likely scientific returns of the FOTRAN experiment will be assessed. The experiment is designed to investigate the effects of a range of blue light stimulations on the movements of wheat coleoptiles at zero-g. The seedlings will be dark-grown, and their movements assessed from infrared time-lapse video recordings made during flight. The photostimulus may be expected to modulate circumnutations of the coleoptiles, by synchronizing, initiating or amplifying these rhythmic movements, and to initiate the classic phototropic response.

Pathogenicity of Leptographium Species Associated with Loblolly Pine Decline

Treesearch

L. G. Eckhardt; J. P. Jones; Kier D. Klepzig

2004-01-01

Freshly lifted seedlings and 21-year-old trees of loblolly pine were wound-inoculated with Leptographium species recovered from the soil and/or roots of trees with loblolly decline symptoms in central Alabama. Seedlings inoculated with L. procerum in the greenhouse produced significantly fewer root initials and a smaller root mass than control...

Planting oaks in the Central Hardwood Region: a shelterwood approach

Treesearch

Dale R. Weigel

1997-01-01

The success of oak seedlings planted under shelterwoods depends on where they are planted, initial seedling size, nursery undercutting treatments, and whether they are top-clipped before planting. These conclusions are based on planting northern red oak (Quercus rubra L.) and white oak (Q. alba L.) under shelterwoods in Indiana and...

Longleaf pine bud development: influence of seedling nutrition

Treesearch

J. P. Barnett; D. P. Jackson; R. K. Dumroese

2010-01-01

A subset of seedlings from a larger study (Jackson and others 2006, 2007) were selected and evaluated for two growing seasons to relate bud development, and root-collar diameter (RCD), and height growth with three nursery fertilization rates. We chose seedlings in the 0.5 (lowest), 2.0 (mid-range), and 4.0 (highest) mg of nitrogen per seedling treatments. Buds moved...

The impact of strip clearcutting on red oak seedling development

Treesearch

Jamie L. Schuler; Michael Boyce; Gary W. Miller

2017-01-01

A mature upland yellow-poplar/red oak stand was harvested using an alternating strip clearcut method. Red oak seedlings were planted across a light gradient between the cut and residual strips to assess the potential ability of the residual strips to foster the development of competitive oak seedlings over time. After one growing season, no differences in seedling...

DELLAs Regulate Chlorophyll and Carotenoid Biosynthesis to Prevent Photooxidative Damage during Seedling Deetiolation in Arabidopsis[C][W

PubMed Central

Cheminant, Soizic; Wild, Michael; Bouvier, Florence; Pelletier, Sandra; Renou, Jean-Pierre; Erhardt, Mathieu; Hayes, Scott; Terry, Matthew J.; Genschik, Pascal; Achard, Patrick

2011-01-01

In plants, light represents an important environmental signal that triggers the production of photosynthetically active chloroplasts. This developmental switch is critical for plant survival because chlorophyll precursors that accumulate in darkness can be extremely destructive when illuminated. Thus, plants have evolved mechanisms to adaptively control plastid development during the transition into light. Here, we report that the gibberellin (GA)-regulated DELLA proteins play a crucial role in the formation of functional chloroplasts during deetiolation. We show that Arabidopsis thaliana DELLAs accumulating in etiolated cotyledons derepress chlorophyll and carotenoid biosynthetic pathways in the dark by repressing the transcriptional activity of the phytochrome-interacting factor proteins. Accordingly, dark-grown GA-deficient ga1-3 mutants (that accumulate DELLAs) display a similar gene expression pattern to wild-type seedlings grown in the light. Consistent with this, ga1-3 seedlings accumulate higher amounts of protochlorophyllide (a phototoxic chlorophyll precursor) in darkness but, surprisingly, are substantially more resistant to photooxidative damage following transfer into light. This is due to the DELLA-dependent upregulation of the photoprotective enzyme protochlorophyllide oxidoreductase (POR) in the dark. Our results emphasize the role of DELLAs in regulating the levels of POR, protochlorophyllide, and carotenoids in the dark and in protecting etiolated seedlings against photooxidative damage during initial light exposure. PMID:21571951

Increased vapor pressure deficit due to higher temperature leads to greater transpiration and faster mortality during drought for tree seedlings common to the forest-grassland ecotone.

PubMed

Will, Rodney E; Wilson, Stuart M; Zou, Chris B; Hennessey, Thomas C

2013-10-01

Tree species growing along the forest-grassland ecotone are near the moisture limit of their range. Small increases in temperature can increase vapor pressure deficit (VPD) which may increase tree water use and potentially hasten mortality during severe drought. We tested a 40% increase in VPD due to an increase in growing temperature from 30 to 33°C (constant dewpoint 21°C) on seedlings of 10 tree species common to the forest-grassland ecotone in the southern Great Plains, USA. Measurement at 33 vs 30°C during reciprocal leaf gas exchange measurements, that is, measurement of all seedlings at both growing temperatures, increased transpiration for seedlings grown at 30°C by 40% and 20% for seedlings grown at 33°C. Higher initial transpiration of seedlings in the 33°C growing temperature treatment resulted in more negative xylem water potentials and fewer days until transpiration decreased after watering was withheld. The seedlings grown at 33°C died 13% (average 2 d) sooner than seedlings grown at 30°C during terminal drought. If temperature and severity of droughts increase in the future, the forest-grassland ecotone could shift because low seedling survival rate may not sufficiently support forest regeneration and migration. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Gravity-regulated formation of the peg in developing cucumber seedlings

NASA Technical Reports Server (NTRS)

Takahashi, H.; Scott, T. K.

1994-01-01

It has been proposed that peg formation in the vascular transition region (TR zone) between the hypocotyl and the root in Cucurbitaceae seedlings is a gravimorphogenetic phenomenon. Initiation of the peg became visible 36 h after imbibition when cucumber (Cucumis sativus L. cv. Burpee Hybrid II) seeds were germinated in a horizontal position at 24 degrees C in the dark. Simultaneously, sedimented amyloplasts (putative statoliths) were apparent in the sheath cells surrounding the vascular strands, and in the cortical cells immediately adjacent to them, in the TR zone. In contrast, the other cortical cells, some of which were destined to develop into the peg, contained amyloplasts which were not sedimented. These results suggest that the graviperception mechanism for peg formation may be like that of statoliths in shoot gravitropism. By 48 h following imbibition, the cells of the TR zone still had sedimented amyloplasts but had lost their sensitivity to gravity, possibly because of their maturation.

Novel plant communities limit the effects of a managed flood to restore riparian forests along a large regulated river

USGS Publications Warehouse

Cooper, D.J.; Andersen, D.C.

2012-01-01

Dam releases used to create downstream flows that mimic historic floods in timing, peak magnitude and recession rate are touted as key tools for restoring riparian vegetation on large regulated rivers. We analysed a flood on the 5th-order Green River below Flaming Gorge Dam, Colorado, in a broad alluvial valley where Fremont cottonwood riparian forests have senesced and little recruitment has occurred since dam completion in 1962. The stable post dam flow regime triggered the development of novel riparian communities with dense herbaceous plant cover. We monitored cottonwood recruitment on landforms inundated by a managed flood equal in magnitude and timing to the average pre-dam flood. To understand the potential for using managed floods as a riparian restoration tool, we implemented a controlled and replicated experiment to test the effects of artificially modified ground layer vegetation on cottonwood seedling establishment. Treatments to remove herbaceous vegetation and create bare ground included herbicide application (H), ploughing (P), and herbicide plus ploughing (H+P). Treatment improved seedling establishment. Initial seedling densities on treated areas were as much as 1200% higher than on neighbouring control (C) areas, but varied over three orders of magnitude among the five locations where manipulations were replicated. Only two replicates showed the expected seedling density rank of (H+P)>P>H>C. Few seedlings established in control plots and none survived 1 year. Seedling density was strongly affected by seed rain density. Herbivory affected growth and survivorship of recruits, and few survived nine growing seasons. Our results suggest that the novel plant communities are ecologically and geomorphically resistant to change. Managed flooding alone, using flows equal to the pre-dam mean annual peak flood, is an ineffective riparian restoration tool where such ecosystem states are present and floods cannot create new habitat for seedling establishment. This problem significantly limits long-term river and riparian management options. ?? 2010 John Wiley & Sons, Ltd.

Seedfall, regeneration, and seedling development in group-selection openings

Treesearch

Philip M. McDonald; Celeste S. Abbott

1994-01-01

Forty-eight openings of 30, 60, and 90 feet in diameter were created in previously unmanaged mixed conifer-hardwood stands on a high-quality site in northern California in 1963. They were an attempt to convert an essentially even-aged forest to an uneven-aged arrangement and comprised the initial cut in the group-selection system. Five conifers and three hardwoods...

Nursery practices, seedling sizes, and field performance.

Treesearch

William I. Stein

1988-01-01

Highlights are presented from a large cooperative study to determine the combined effects of nursery cultural practices on the initial size and subsequent field performance of 2+0 Douglas-fir seedlings. The study involved seven sources of stock produced in three different nurseries and field plantings made over 3 years on 28 sites in southwestern Oregon. Seedbed...

Control of brush regrowth with herbicides on pine plantations in northern California

Treesearch

Jay R. Bentley; Kenneth M. Estes

1978-01-01

On large plots cleared in 1961 at three California mountain locations, different herbicide treatments were applied once, twice, or three times in consecutive years, beginning in 1962. Results were evaluated in 1965. A single spray was unsatisfactory; only the initial seedlings and weaker sprouting plants were killed, and many new seedlings became established in 1963...

Relationship between tillage intensity and initial growth of loblolly pine seedlings

Treesearch

M. Chad Lincoln; Rodney E. Will; Emily A. Carter; John R. Britt; Lawrence A. Morris

2006-01-01

To determine the relationship between changes in soil attributes associated with differing tillage intensities and growth of loblolly pine seedlings, we measured soil moisture, nitrogen (N) availability, and soil strength across a range of tillage treatments on an Orangeburg soil series near Cuthbert, GA (four replications). We then correlated these measurements to the...

Development of red oak seedlings using plastic shelters on good-to- excellent hardwood sites in West Virginia

Treesearch

H. Clay Smith; H. Clay Smith

1993-01-01

Plastic shelters were used to grow red oak seedlings on good-to-excellent Appalachian hardwood growing sites in north central West Virginia. Preliminary results indicate that shelters have the potential to stimulate development of red oak seedling height growth, especially if height growth continues once the seedling tops are above the 5-foot-tall shelters.

Longleaf Pine Root System Development and Seedling Quality in Response to Copper Root Pruning and Cavity Size

Treesearch

Mary Anne Sword Sayer; Shi-Jean Susana Sung; James D. Haywood

2011-01-01

Cultural practices that modify root system structure in the plug of container-grown seedlings have the potential to improve root system function after planting. Our objective was to assess how copper root pruning affects the quality and root system development of longleaf pine seedlings grown in three cavity sizes in a greenhouse. Copper root pruning increased seedling...

Functional Profiling Identifies Genes Involved in Organ-Specific Branches of the PIF3 Regulatory Network in Arabidopsis[C][W

PubMed Central

Sentandreu, Maria; Martín, Guiomar; González-Schain, Nahuel; Leivar, Pablo; Soy, Judit; Tepperman, James M.; Quail, Peter H.; Monte, Elena

2011-01-01

The phytochrome (phy)-interacting basic helix-loop-helix transcription factors (PIFs) constitutively sustain the etiolated state of dark-germinated seedlings by actively repressing deetiolation in darkness. This action is rapidly reversed upon light exposure by phy-induced proteolytic degradation of the PIFs. Here, we combined a microarray-based approach with a functional profiling strategy and identified four PIF3-regulated genes misexpressed in the dark (MIDAs) that are novel regulators of seedling deetiolation. We provide evidence that each one of these four MIDA genes regulates a specific facet of etiolation (hook maintenance, cotyledon appression, or hypocotyl elongation), indicating that there is branching in the signaling that PIF3 relays. Furthermore, combining inferred MIDA gene function from mutant analyses with their expression profiles in response to light-induced degradation of PIF3 provides evidence consistent with a model where the action of the PIF3/MIDA regulatory network enables an initial fast response to the light and subsequently prevents an overresponse to the initial light trigger, thus optimizing the seedling deetiolation process. Collectively, the data suggest that at least part of the phy/PIF system acts through these four MIDAs to initiate and optimize seedling deetiolation, and that this mechanism might allow the implementation of spatial (i.e., organ-specific) and temporal responses during the photomorphogenic program. PMID:22108407

The role of the megagametophyte in maintaining loblolly pine (Pinus taeda L.) seedling arginase gene expression in vitro.

PubMed

Todd, Christopher D; Gifford, David J

2002-05-01

Following loblolly pine (Pinus taeda L.) seed germination, storage-protein breakdown in the megagametophyte and in the seedling results in a large increase in the seedling's free amino acid pool. A substantial portion of both the storage proteins and the amino acid pool is arginine, a very efficient nitrogen-storage compound. Free arginine is hydrolyzed in the seedling by the enzyme arginase (EC 3.5.3.1), which is under strong developmental control. At present, regulation of arginase in conifers is not well understood. Here we report the utilization of an in vitro culture system to address the separate impacts of the seedling and megagametophyte tissues on arginase enzyme activity, protein levels and patterns of gene expression. We also describe the generation of an anti-arginase antibody prepared from a histidine-tagged loblolly pine arginase fusion protein expressed in Escherichia coli. Our results indicate that arginase gene expression in the seedling is initiated by the seedling itself and then maintained or up-regulated by the megagametophyte. The contribution of storage-protein breakdown and the free amino acid pool, particularly arginine, in this regulation is also addressed.

Refugial forests of the southern Appalachians: photosynthesis and survival in current-year Abies fraseri seedlings.

PubMed

Johnson, Daniel M; Smith, William K

2005-11-01

Fraser fir (Abies fraseri (Pursh) Poiret) is an endemic, high-elevation conifer confined to six relict mountaintop communities in the southern Appalachian Mountains, USA. High adult mortality has occurred over the past 50 years, possibly the result of an introduced insect (Adelges piceae Ratzeburg), air pollution, or both. Knowledge of the mechanisms of and limitations to seedling establishment may allow reestablisment and perpetuation of this unique community type, notwithstanding global climate change. We monitored seedling emergence and mortality in relation to photosynthetic performance and water relations in microsites differing in canopy openness (sunlight exposure) over the summer of 2004. Abundance of cotyledonous seedlings in early summer was 2.3 times greater (849 versus 366 seedlings m(-2)) in microsites with lower sky exposure (greater canopy closure) than in microsites with greater sky exposure (greater canopy openness). In contrast, late-season abundance and survival were greater in areas beneath more open canopies than in areas beneath less open canopies (3.3 times and 11.7 times greater, respectively). However, newly emerged seedling survival in a completely open site (no overhead canopy) was zero, despite an initial density of 124 seedlings m(-2). Seedling water status was similar in open- and closed-canopy sites (-0.52 and -0.74 MPa, respectively). Photosynthetic carbon gain was higher in newly emerged seedlings at open canopy than at closed canopy sites, especially during early morning. Based on photosynthetic light response curves and measured sunlight regimes, seedlings in open canopy sites were estimated to assimilate 3.3-4.5 times more carbon than seedlings at closed sites. Reductions in carbon gain of closed-site seedlings, primarily a result of limited sunlight, corresponded to substantial increases in seedling mortality (98 versus 79% in open canopy sites). Thus, sunlight exposure, which reflects overstory canopy structure, appears to be an important factor influencing newly emerged seedling survival and distribution.

Spatial and temporal regulation of the metabolism of reactive oxygen and nitrogen species during the early development of pepper (Capsicum annuum) seedlings

PubMed Central

Airaki, Morad; Leterrier, Marina; Valderrama, Raquel; Chaki, Mounira; Begara-Morales, Juan C.; Barroso, Juan B.; del Río, Luis A.; Palma, José M.; Corpas, Francisco J.

2015-01-01

Background and Aims The development of seedlings involves many morphological, physiological and biochemical processes, which are controlled by many factors. Some reactive oxygen and nitrogen species (ROS and RNS, respectively) are implicated as signal molecules in physiological and phytopathological processes. Pepper (Capsicum annuum) is a very important crop and the goal of this work was to provide a framework of the behaviour of the key elements in the metabolism of ROS and RNS in the main organs of pepper during its development. Methods The main seedling organs (roots, hypocotyls and green cotyledons) of pepper seedlings were analysed 7, 10 and 14 d after germination. Activity and gene expression of the main enzymatic antioxidants (catalase, ascorbate–glutathione cycle enzymes), NADP-generating dehydrogenases and S-nitrosoglutathione reductase were determined. Cellular distribution of nitric oxide (·NO), superoxide radical (O2·–) and peroxynitrite (ONOO–) was investigated using confocal laser scanning microscopy. Key Results The metabolism of ROS and RNS during pepper seedling development was highly regulated and showed significant plasticity, which was co-ordinated among the main seedling organs, resulting in correct development. Catalase showed higher activity in the aerial parts of the seedling (hypocotyls and green cotyledons) whereas roots of 7-d-old seedlings contained higher activity of the enzymatic components of the ascorbate glutathione cycle, NADP-isocitrate dehydrogenase and NADP-malic enzyme. Conclusions There is differential regulation of the metabolism of ROS, nitric oxide and NADP dehydrogenases in the different plant organs during seedling development in pepper in the absence of stress. The metabolism of ROS and RNS seems to contribute significantly to plant development since their components are involved directly or indirectly in many metabolic pathways. Thus, specific molecules such as H2O2 and NO have implications for signalling, and their temporal and spatial regulation contributes to the success of seedling establishment. PMID:25808658

Growth and root development of four mangrove seedlings under varying salinity

NASA Astrophysics Data System (ADS)

Basyuni, M.; Keliat, D. A.; Lubis, M. U.; Manalu, N. B.; Syuhada, A.; Wati, R.; Yunasfi

2018-03-01

This present study describes four mangrove seedlings namely Bruguiera cylindrica, B. sexangula, Ceriops tagal, and Rhizophora apiculata in response to salinity with particular emphasis to root development. The seedlings of four mangroves were grown for 5 months in 0%, 0.5%, 1.5%, 2.0% and 3.0% salt concentration. Salinity significantly decreased the growth (diameter and plant height) of all mangrove seedlings. Root developments were observed from the tap and lateral root. The number, length and diameter of both roots-typed of B. cylindrica, B. sexangula and C. tagal seedlings significantly decreased with increasing salt concentration with optimum development at 0.5% salinity. By contrast, the number, length, and diameter of tap root of R. apiculata seedlings were significantly enhanced by salt with maximal stimulation at 0.5%, and this increase was attenuated by increasing salinity. On the other hand, lateral root development of R. apiculata significantly thrived up to 1.5% salinity then decreasing with the increasing salinity. The different response of root development suggested valuable information for mangrove rehabilitation in North Sumatra and their adaption to withstand salt stress.

Transcriptional and posttranscriptional regulation of the glycolate oxidase gene in tobacco seedlings.

PubMed

Barak, S; Nejidat, A; Heimer, Y; Volokita, M

2001-03-01

The roles of light and of the putative plastid signal in glycolate oxidase (GLO) gene expression were investigated in tobacco (Nicotiana tabacum cv. Samsun NN) seedlings during their shift from skotomorphogenic to photomorphogenic development. GLO transcript and enzyme activities were detected in etiolated seedlings. Their respective levels increased three- and six-fold during 96 h of exposure to light. The GLO transcript was almost undetectable in seedlings in which chloroplast development was impaired by photooxidation with the herbicide norflurazon. In transgenic tobacco seedlings, photooxidation inhibited the light-dependent increase in GUS activity when it was placed under the regulation of the GLO promoter P(GLO). However, even under these photooxidative conditions, a continuous increase in GUS activity was observed as compared to etiolated seedlings. When GUS expression was driven by the CaMV 35S promoter (P35S), no apparent difference was observed between etiolated, deetiolated and photooxidized seedlings. These observations indicate that the effects of the putative plastid development signal and light on GUS expression can be separated. Translational yield analysis indicated that the translation of the GUS transcript in P(GLO)::GUS seedlings was enhanced 30-fold over that of the GUS transcript in P35S::GUS seedlings. The overall picture emerging from these results is that in etiolated seedlings GLO transcript, though present at a substantial level, is translated at a low rate. Increased GLO transcription is enhanced, however, in response to signals originating from the developing plastids. GLO gene expression is further enhanced at the translational level by a yet undefined light-dependent mechanism.

Dying piece by piece: carbohydrate dynamics in aspen seedlings under severe carbon stress and starvation

NASA Astrophysics Data System (ADS)

Wiley, Erin; Chow, Pak; Landhäusser, Simon

2016-04-01

Carbon stress and starvation remain poorly understood in trees, despite their potential role in mortality from a variety of agents. To explore the effects of carbon stress on nonstructural carbohydrate (NSC) dynamics and recovery potential and to examine the process of starvation, we grew aspen seedlings under one of three levels of shade: 40% (light shade), 8% (medium shade), and 4% (dark shade) of full sunlight. We then exposed seedlings to 24 hours darkness at either 20° or 28° C until trees had died. Periodically, seedlings were harvested for NSC analysis and to measure stem and root respiration. In addition, some seedlings were moved back into the light to determine if recovery was possible at certain points during starvation. Specifically, we sought to address the following questions: 1) Do NSC concentrations or mass influence tree survival under carbon stress? 2) At what carbohydrate levels do trees fail to recover and starve? 3) Does temperature affect the NSC level at which trees starve? Increasing shade reduced growth, but surprisingly did not reduce NSC levels, except in a portion of deep shade seedlings that experienced dieback. Once in darkness, leaves died first, with final NSC levels ranging from ~4% (Medium shade, 28 degrees) to 7.5% (Light shade). Stem death generally occurred gradually down the stem. Stem tissues retained ~1-2% NSC when dead. Recovery was still possible when only the upper half of the stem had died; at this point, seedlings had relatively high root NSC levels in their remaining roots (7-10%), with 1-3% starch. No trees recovered after the whole stem had died, at which point, some trees root systems were completely dead. However, most retained substantial amounts of live roots, averaging 5-6% NSC, with 0.25-1.5% starch. Despite the initially similar NSC concentrations, light shade seedlings took longer to reach half stem and whole stem death than seedlings from medium and dark shade. Longer survival times were associated with greater initial NSC pool sizes and lower mass-specific respiration rates. Higher temperatures reduced the time until tissue death and also tended to reduce NSC levels at death in some tissues. Survival time during starvation appeared to be controlled not only by the size of initial reserves, but by the rate of respiration. Relatively high leaf NSC levels of dead leaves observed during drought and during fall leaf abscission are within the range of leaf NSC levels of starved leaves seen here. Patterns of nonzero tissue NSC and the piecewise progression of mortality often observed in mature trees are not inconsistent with the process of carbon starvation, which may contribute to tree death by many causes.

Composite Cucurbita pepo plants with transgenic roots as a tool to study root development

PubMed Central

Ilina, Elena L.; Logachov, Anton A.; Laplaze, Laurent; Demchenko, Nikolay P.; Pawlowski, Katharina; Demchenko, Kirill N.

2012-01-01

Background and Aims In most plant species, initiation of lateral root primordia occurs above the elongation zone. However, in cucurbits and some other species, lateral root primordia initiation and development takes place in the apical meristem of the parental root. Composite transgenic plants obtained by Agrobacterium rhizogenes-mediated transformation are known as a suitable model to study root development. The aim of the present study was to establish this transformation technique for squash. Methods The auxin-responsive promoter DR5 was cloned into the binary vectors pKGW-RR-MGW and pMDC162-GFP. Incorporation of 5-ethynyl-2′-deoxyuridine (EdU) was used to evaluate the presence of DNA-synthesizing cells in the hypocotyl of squash seedlings to find out whether they were suitable for infection. Two A. rhizogenes strains, R1000 and MSU440, were used. Roots containing the respective constructs were selected based on DsRED1 or green fluorescent protein (GFP) fluorescence, and DR5::Egfp-gusA or DR5::gusA insertion, respectively, was verified by PCR. Distribution of the response to auxin was visualized by GFP fluorescence or β-glucuronidase (GUS) activity staining and confirmed by immunolocalization of GFP and GUS proteins, respectively. Key Results Based on the distribution of EdU-labelled cells, it was determined that 6-day-old squash seedlings were suited for inoculation by A. rhizogenes since their root pericycle and the adjacent layers contain enough proliferating cells. Agrobacterium rhizogenes R1000 proved to be the most virulent strain on squash seedlings. Squash roots containing the respective constructs did not exhibit the hairy root phenotype and were morphologically and structurally similar to wild-type roots. Conclusions The auxin response pattern in the root apex of squash resembled that in arabidopsis roots. Composite squash plants obtained by A. rhizogenes-mediated transformation are a good tool for the investigation of root apical meristem development and root branching. PMID:22553131

Pregermination heat shock and seedling growth of fire-following Fabaceae from four Mediterranean-climate regions

NASA Astrophysics Data System (ADS)

Hanley, Mick E.; Fenner, Michael; Ne'eman, Gidi

2001-12-01

The role of heat-shock in stimulating the germination of soil-stored seeds from fire-following plant species is well known. However, the effects of high pre-germination temperatures on subsequent seedling growth are less well understood. In this study, we examined the effect of pre-germination heat shock at five temperatures (60°, 75°, 90°, 105° and 120°C, each applied for 5 min) on the seedling growth of four, fire-following Fabaceae species from four Mediterranean-type ecosystems; Hippocrepis multisiliquosa (Israel), Gastrolobium villosum (Western Australia), Cyclopia pubescens (South Africa) and Lupinus succulentus (California). Following heat treatment and subsequent germination, seedlings were grown in controlled conditions before being harvested at either 10, 20- or 40 d old. A significant increase in mean dry weight biomass was found at 10 days for Hippocrepis seedlings germinated from seeds pre-heated to 90°C. However, subsequent comparison of mean dry weight biomass for seedlings of this species at 20 and 40 d old showed no significant response to heat shock pre-treatment. Similarly, an initial increase in growth of Gastrolobium seedlings germinated from seeds heated to 90° and 105°C disappeared as the plants matured. Seedling growth of Lupinus and Cyclopia was unaffected by the pre-germination heat treatment of their seeds. Since seedling competition is influenced by the size and growth rates of neighbouring plants, any changes in seedling growth rates as a consequence of the temperature environment experienced by their seeds, may therefore influence patterns of post-fire plant community recovery.

Flowering, die-back and recovery of a semelparous woody bamboo in the Atlantic Forest

NASA Astrophysics Data System (ADS)

Montti, Lía; Campanello, Paula I.; Goldstein, Guillermo

2011-07-01

Chusquea ramosissima is a semelparous woody bamboo growing in the understory of the semideciduous Atlantic Forest that increases in abundance after disturbance and consequently has profound effects on vegetation dynamics. Flowering and death of C. ramosissima may open a window of opportunity leaving space vacant for the recruitment of tree seedlings. We describe the flowering pattern and seedling demography of this species at different spatio-temporal scales between the years 2001 and 2009, and evaluate if tree seedling abundance of canopy species increased after the flowering event. At a landscape scale, flowering sites were interspersed with sites that did not flower. At a local scale, the flowering extended over 5 years, with flowering and non-flowering culms intermingled, also in small patches (i.e., 4 m 2). Seeds germinated soon after flowering and die-back. Four successive seedling cohorts were studied. Mortality rate was high during the first 4 months after seedling emergence but several fast-growing seedlings were able to become established successfully. At the end of the study, 10%-20% of the initial number of bamboo seedlings in each cohort survived. Seedling abundance of tree canopy species was similar in flowering and non-flowering sites. C. ramosissima was able to re-colonize and perpetuate in sites it previously occupied. The coexistence of flowering and non-flowering culms at different spatio-temporal scales and clonal growth by rhizomes, together with the successful bamboo seedlings establishment, enhanced bamboo persistence in gaps and disturbed sites. Flowering and death of C. ramosissima did not facilitate seedling growth of canopy tree species.

Limited evolutionary divergence of seedlings after the domestication of plant species.

PubMed

Milla, R; Morente-López, J

2015-01-01

The most vulnerable stage in the life of plants is the seedling. The transition from wild to agricultural land that plants experienced during and after domestication implied a noticeable change in the seedlings' environment. Building on current knowledge of seedling ecology, and on previous studies of cassava, we hypothesise that cultivation should have promoted epigeal germination of seedlings, and more exposed and photosynthetic cotyledons. To test this hypothesis, we phenotyped seedling morpho-functional traits in a set of domesticated and wild progenitor accessions of 20 Eudicot herbaceous crop species. Qualitative traits like epi- versus hypogeal germination, leafy versus storage type of cotyledons, or crypto- versus phanerocotyledonar germination, remained conserved during the domestication of all 20 species. Lengths of hypocotyls and epicotyls, of cotyledon petioles, and indices of cotyledon exposure to the aboveground environment changed during evolution under cultivation. However, those changes occurred in diverse directions, depending on the crop species. No common seedling phenotypic convergence in response to domestication was thus detected among the group of species studied here. Also, none of the 20 crops evolved in accordance with our initial hypothesis. Our results reject the idea that strong selective filters exerted unconsciously by artificial selection should have resulted in generalised channelling of seedling morphology towards more productive and more herbivore risky phenotypes. This result opens up unexplored opportunities for directional breeding of seedling traits. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

Research and management in a young northern red oak seedling seed orchard

Treesearch

S.E. Schlarbaum; J.L. McConnell; L.R. Barber; R.A. Cox; J.F. Grant; Paul P. Kormanik; T. La Farge; P.L. Lambdin; S.W. Oak; C.K. Proffitt; J.R. Rhea; T. Tibbs

1994-01-01

A northern red oak progeny test was thinned at age 15 to produce a seedling seed orchard. Studies were initiated to determine relationships between acorn production and seed source. Acorn production was observed in 1984-1986 and 1989-1992.Family differences were observed in reproductive maturity. Large differences in size of acorns from the same tree were observed...

Responses of Wound-Inoculated Seedlings of Pinus elliottii var. elliottii and Pinus taeda to Mycelial Cultures Derived from Multople and Singel Basidiospores of Cronartium quercuum f. sp. fusiforme

Treesearch

T. Miller; K.P. Gramacho; R.A. Schmidt; H.V. Amerson; E.G. Kuhlman

1998-01-01

In 1991, a series of experiments was initiated to examine the effectiveness and research value of inoculating 6-week-old seedlings of slash (Pinus elliottii var. elliottii) and loblolly pine (P. raeda) with suspensions of basidiospores of Cronartium quercuum f. sp. fusiforme...

Insects affecting establishment of northern red oak seedlings in central Pennsylvania

Treesearch

J. Galford; L.R. Auchmoody; H.C. Smith; R.S. Walters

1991-01-01

Studies to evaluate the impact of insects on the establishment of advance oak regeneration in Pennsylvania were initiated in 1989. The populations and species of insects feeding on germinating acorns and new seedlings, their activity periods, and the damage caused by these insects were studied in relation to overstory-density (40, 60, and 100 percent relative density)...

Conducting seedling stock type trials: A new approach to an old question

Treesearch

Jeremiah R. Pinto; R. Kasten Dumroese; Anthony S. Davis; Thomas D. Landis

2011-01-01

Seedlings for reforestation and restoration come in many shapes and sizes, i.e., a variety of stocktypes. With so many choices available, land managers commonly ask which stocktype will best meet their management objectives. For years, stocktype studies have been initiated in search of an answer to this question, but few have been done without some degree of...

New sources of adult plant and seedling resistance to Puccinia coronata f. sp. avenae identified among Avena sativa accessions of the national small grains collection

USDA-ARS?s Scientific Manuscript database

Accessions of cultivated oat (A. sativa L.) from the USDA-ARS Small Grains Collection in Aberdeen, ID were characterized for adult plant resistance (APR) and seedling resistance to crown rust, caused by Puccinia coronata f. sp. avenae (Pca). Initially, 607 oat accessions with diverse geographic orig...

Effects of site preparation treatments on early growth and survival of planted longleaf pine (Pinus palustris Mill.) seedlings in North Carolina

Treesearch

Benjamin O. Knapp; G. Geoff Wang; Joan L. Walker; Susan Cohen

2006-01-01

We tested the effects of eight site preparation treatments on early growth and survival of container-grown longleaf pine (Pinus palustris Mill.) seedlings. Treatments included an untreated check, six combinations of two initial vegetation control treatments (chopping or herbicide) with three planting site conditions (flat [no additional treatment],...

Nursery stock quality as an indicator of bottomland hardwood forest restoration success in the Lower Mississippi River Alluvial Valley

Treesearch

Douglass F. Jacobs; Rosa C. Goodman; Emile S. Gardiner; K Frances Salifu; Ronald P. Overton; George Hernandez

2012-01-01

Seedling morphological quality standards are lacking for bottomland hardwood restoration plantings in the Lower Mississippi River Alluvial Valley, USA, which may contribute toward variable restoration success. We measured initial seedling morphology (shoot height, root collar diameter, number of first order lateral roots, fresh mass, and root volume), second year field...

Study on tissue culture for Gelidium seedling

NASA Astrophysics Data System (ADS)

Pei, Lu-Qing; Luo, Qi-Jun; Fei, Zhi-Qing; Ma, Bin

1996-06-01

As seedling culture is a crucial factor for successful cultivation of Gelidium, the authors researched tissue culture technology for producing seedlings. The morphogeny and experimental ecology were observed and studied fully in 2 5 mm isolated tissue fragments. Regeneration, appearance of branching creepers and attaching structure and new erect seedlings production and development were studied. Fragments were sown on bamboo slice and vinylon rope. The seedlings were cultured 20 30 days indoor, then cultured in the sea, where the density of erect seedlings was 3 19 seedlings/cm2, growth rate was 3.84% day. The frond arising from seedlings directly was up to 10 cm per year. The ecological conditions for regenerated seedlings are similar to the natural ones. The regenerated seedlings are suitable for raft culture in various sea areas.

Vine maple (Acer circinatum) clone growth and reproduction in managed and unmanaged coastal Oregon douglas-fir forests

USGS Publications Warehouse

O'Dea, Mary E.; Zasada, John C.; Tappeiner, John C.

1995-01-01

Vine maple (Acer circinatum Pursh.) clone development, expansion, and regeneration by seedling establishment were studied in 5-240 yr old managed and unmanaged Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands in coastal Oregon. Stem length, number of stems, and crown area were all significantly (P @10 m long and basal sprouts 1-2 m long; some stems had been pinned to the forest floor by fallen trees or branches and had layered. In stands >120 yr in age, clones were often quite complex, composed of several decumbent stems each of which connected the ramets of 1-10 new aerial stems. Vine maple clone expansion occurs by the layering of long aerial stems. Over 95% of the layered stems we observed had been pinned to the forest floor by fallen debris. Unsevered stems that we artificially pinned to the forest floor initiated roots within 1 yr. Thinning may favor clonal expansion because fallen slash from thinning often causes entire clones to layer, not just individual stems. Clonal vine maple seed production and seedling establishment occurred in all stages of stand development except dense, young stands following crown closure. There were more seedlings in thinned stands than in unthinned stands and in unburned clearcuts than in burned clearcuts.

Naturally developed seedling roots of five western conifers.

Treesearch

William I. Stein

1978-01-01

Two-year-old seedlings grown from seed outdoors in three southwestern Oregon soils were excavated to determine their root development. Roots of Douglas-fir, ponderosa pine, sugar pine, grand fir, and incense-cedar seedlings differed substantially in total extent, form, and balance in relation to tops. Information on the natural development of roots provides a benchmark...

Whitebark pine facilitation at treeline: potential interactions for disruption by an invasive pathogen.

PubMed

Tomback, Diana F; Blakeslee, Sarah C; Wagner, Aaron C; Wunder, Michael B; Resler, Lynn M; Pyatt, Jill C; Diaz, Soledad

2016-08-01

In stressful environments, facilitation often aids plant establishment, but invasive plant pathogens may potentially disrupt these interactions. In many treeline communities in the northern Rocky Mountains of the U.S. and Canada, Pinus albicaulis, a stress-tolerant pine, initiates tree islands at higher frequencies than other conifers - that is, leads to leeward tree establishment more frequently. The facilitation provided by a solitary (isolated) P. albicaulis leading to tree island initiation may be important for different life-history stages for leeward conifers, but it is not known which life-history stages are influenced and protection provided. However, P. albicaulis mortality from the non-native pathogen Cronartium ribicola potentially disrupts these facilitative interactions, reducing tree island initiation. In two Rocky Mountain eastern slope study areas, we experimentally examined fundamental plant-plant interactions which might facilitate tree island formation: the protection offered by P. albicaulis to leeward seed and seedling life-history stages, and to leeward krummholz conifers. In the latter case, we simulated mortality from C. ribicola for windward P. albicaulis to determine whether loss of P. albicaulis from C. ribicola impacts leeward conifers. Relative to other common solitary conifers at treeline, solitary P. albicaulis had higher abundance. More seeds germinated in leeward rock microsites than in conifer or exposed microsites, but the odds of cotyledon seedling survival during the growing season were highest in P. albicaulis microsites. Planted seedling survival was low among all microsites examined. Simulating death of windward P. albicaulis by C. ribicola reduced shoot growth of leeward trees. Loss of P. albicaulis to exotic disease may limit facilitation interactions and conifer community development at treeline and potentially impede upward movement as climate warms.

Returning fire to Ozark Highland forest ecosystems: Effects on advance regeneration

Treesearch

Daniel C. Dey; George Hartman

2005-01-01

In mature forests of the Ozark Highlands, MO, USA, we evaluated fire effects on the survival and growth of tree seedlings and saplings (i.e., advance regeneration), and used this information to develop species-specific models that predict the probability of survival based on initial tree size and number of times burned. A 1000 ha forest area was divided into five units...

Utilizing ARC EMCS Seedling Cassettes as Highly Versatile Miniature Growth Chambers for Model Organism Experiments

NASA Technical Reports Server (NTRS)

Freeman, John L.; Steele, Marianne K.; Sun, Gwo-Shing; Heathcote, David; Reinsch, S.; DeSimone, Julia C.; Myers, Zachary A.

2014-01-01

The aim of our ground testing was to demonstrate the capability of safely putting specific model organisms into dehydrated stasis, and to later rehydrate and successfully grow them inside flight proven ARC EMCS seedling cassettes. The ARC EMCS seedling cassettes were originally developed to support seedling growth during space flight. The seeds are attached to a solid substrate, launched dry, and then rehydrated in a small volume of media on orbit to initiate the experiment. We hypothesized that the same seedling cassettes should be capable of acting as culture chambers for a wide range of organisms with minimal or no modification. The ability to safely preserve live organisms in a dehydrated state allows for on orbit experiments to be conducted at the best time for crew operations and more importantly provides a tightly controlled physiologically relevant growth experiment with specific environmental parameters. Thus, we performed a series of ground tests that involved growing the organisms, preparing them for dehydration on gridded Polyether Sulfone (PES) membranes, dry storage at ambient temperatures for varying periods of time, followed by rehydration. Inside the culture cassettes, the PES membranes were mounted above blotters containing dehydrated growth media. These were mounted on stainless steel bases and sealed with plastic covers that have permeable membrane covered ports for gas exchange. The results showed we were able to demonstrate acceptable normal growth of C.elegans (nematodes), E.coli (bacteria), S.cerevisiae (yeast), Polytrichum (moss) spores and protonemata, C.thalictroides (fern), D.discoideum (amoeba), and H.dujardini (tardigrades). All organisms showed acceptable growth and rehydration in both petri dishes and culture cassettes initially, and after various time lengths of dehydration. At the end of on orbit ISS European Modular Cultivation System experiments the cassettes could be frozen at ultra-low temperatures, refrigerated, or chemically preserved before being returned to Earth for analyses. Our results suggest that with protocol modifications and future verification testing we can utilize the versatile EMCS to conduct tightly controlled experiments inside our culture cassettes for a wide variety of organisms. These physiological experiments would be designed to answer questions at the molecular level about the specific stress responses of space flight.

Bottles to trees: Plastic beverage bottles as an alternative nursery growing container for reforestation in developing countries.

PubMed

Khurram, Safiullah; Burney, Owen T; Morrissey, Robert C; Jacobs, Douglass F

2017-01-01

Reforestation is needed globally to help restore degraded sites, combat desertification, protect watersheds, and provide forest products. This involves planting forest tree seedlings grown in local nurseries, but technologies to produce quality seedlings are lacking in developing countries. Modern nursery containers used to propagate seedlings have internal-surface barriers (ribs or ridges) or side-slits to prevent root spiraling. These are cost prohibitive or unavailable in developing countries and so polybags (plastic bags) are more commonly used, despite their tendency to produce seedlings with deformed root systems that have less potential to establish on field sites. Discarded plastic bottles, which are readily available worldwide, may be a feasible alternative for seedling propagation. We conducted two experiments to assess the potential of repurposed plastic beverage bottles to grow quality trees: 1) Container Comparison-to evaluate Arizona walnut (Juglans major [Toor.] Heller) and Afghan pine (Pinus eldarica Medw.) seedling root and shoot development in two plastic bottle types compared to modern nursery containers and polybags, and 2) Bottle Modification-to examine the effects of root spiraling prevention techniques (side-slits, internal-ridges, and control) and container opacity (green, black, and clear) on Afghan pine seedling morphological attributes. Nursery growth and first-year seedling field performance were evaluated for both experiments. In experiment one, seedlings of both species had fewer spiraled roots in bottle containers compared to polybags. Arizona walnut had more fibrous root systems in polybags, while Afghan pine root system fibrosity was greatest in bottle containers. First-year field performance of both species was not affected by container type. In experiment two, less spiraled roots occurred in containers with air-slits and interior-ridges compared to the control. The effects of container opacity on seedling morphology were inconsistent. Root spiral prevention and opacity had no influence on Afghan pine one-year survival, field height and diameter, with the exception of opacity for height growth, whereby seedlings grown in green containers were taller than those grown in black containers, but seedlings grown in clear containers were similar to both. Our results provide the first evidence that plastic bottle containers may provide an effective alternative for production of high quality seedlings, which may benefit agroforestry, reforestation, restoration, and conservation programs in developing countries.

Bottles to trees: Plastic beverage bottles as an alternative nursery growing container for reforestation in developing countries

PubMed Central

Khurram, Safiullah; Burney, Owen T.; Morrissey, Robert C.

2017-01-01

Reforestation is needed globally to help restore degraded sites, combat desertification, protect watersheds, and provide forest products. This involves planting forest tree seedlings grown in local nurseries, but technologies to produce quality seedlings are lacking in developing countries. Modern nursery containers used to propagate seedlings have internal-surface barriers (ribs or ridges) or side-slits to prevent root spiraling. These are cost prohibitive or unavailable in developing countries and so polybags (plastic bags) are more commonly used, despite their tendency to produce seedlings with deformed root systems that have less potential to establish on field sites. Discarded plastic bottles, which are readily available worldwide, may be a feasible alternative for seedling propagation. We conducted two experiments to assess the potential of repurposed plastic beverage bottles to grow quality trees: 1) Container Comparison–to evaluate Arizona walnut (Juglans major [Toor.] Heller) and Afghan pine (Pinus eldarica Medw.) seedling root and shoot development in two plastic bottle types compared to modern nursery containers and polybags, and 2) Bottle Modification–to examine the effects of root spiraling prevention techniques (side-slits, internal-ridges, and control) and container opacity (green, black, and clear) on Afghan pine seedling morphological attributes. Nursery growth and first-year seedling field performance were evaluated for both experiments. In experiment one, seedlings of both species had fewer spiraled roots in bottle containers compared to polybags. Arizona walnut had more fibrous root systems in polybags, while Afghan pine root system fibrosity was greatest in bottle containers. First-year field performance of both species was not affected by container type. In experiment two, less spiraled roots occurred in containers with air-slits and interior-ridges compared to the control. The effects of container opacity on seedling morphology were inconsistent. Root spiral prevention and opacity had no influence on Afghan pine one-year survival, field height and diameter, with the exception of opacity for height growth, whereby seedlings grown in green containers were taller than those grown in black containers, but seedlings grown in clear containers were similar to both. Our results provide the first evidence that plastic bottle containers may provide an effective alternative for production of high quality seedlings, which may benefit agroforestry, reforestation, restoration, and conservation programs in developing countries. PMID:28562684

Development of machine-vision system for gap inspection of muskmelon grafted seedlings.

PubMed

Liu, Siyao; Xing, Zuochang; Wang, Zifan; Tian, Subo; Jahun, Falalu Rabiu

2017-01-01

Grafting robots have been developed in the world, but some auxiliary works such as gap-inspecting for grafted seedlings still need to be done by human. An machine-vision system of gap inspection for grafted muskmelon seedlings was developed in this study. The image acquiring system consists of a CCD camera, a lens and a front white lighting source. The image of inspected gap was processed and analyzed by software of HALCON 12.0. The recognition algorithm for the system is based on principle of deformable template matching. A template should be created from an image of qualified grafted seedling gap. Then the gap image of the grafted seedling will be compared with the created template to determine their matching degree. Based on the similarity between the gap image of grafted seedling and the template, the matching degree will be 0 to 1. The less similar for the grafted seedling gap with the template the smaller of matching degree. Thirdly, the gap will be output as qualified or unqualified. If the matching degree of grafted seedling gap and the template is less than 0.58, or there is no match is found, the gap will be judged as unqualified; otherwise the gap will be qualified. Finally, 100 muskmelon seedlings were grafted and inspected to test the gap inspection system. Results showed that the gap inspection machine-vision system could recognize the gap qualification correctly as 98% of human vision. And the inspection speed of this system can reach 15 seedlings·min-1. The gap inspection process in grafting can be fully automated with this developed machine-vision system, and the gap inspection system will be a key step of a fully-automatic grafting robots.

[Effects of different fungi on symbiotic seed germination of two Dendrobium species].

PubMed

Zi, Xiao-meng; Gao, Jiang-yun

2014-09-01

The epiphytic orchid, Dendrobium aphyllum and D. devonianum are used as traditional Chinese medicine, and became locally endangered in recent years because of over-collection. We test the effect of inoculations of endophytic fungi FDaI7 (Tulasnella sp.), FDd1 (Epulorhiza sp. ) and FCb4 (Epulorhiza sp.), which isolated from D. aphyllum, D. denonianum and Cymbidium mannii, respectively, on artificial substrate in these two Dendrobium species. In the symbiotic germination experiment, FDaI7 and FDd1 were effective for protocorm formation and seedling development of D. aphyllum and D. denonianum separately. After 60 days, 14.46% of the D. aphyllum seeds grown to protocorms and 12.07% developed to seedlings inoculated only with FDaI7, while contrasted with 0 when inoculated the other two isolates and non-inoculation treatment. However, in D. denonianum, seeds only grown to protocorms and developed to seedlings when inoculated with FDd1, the percentages were 44.36% and 42.91% distinguishingly. High specificity was shown in symbiotic germination on artificial substrate of Dendrobium. Protocorms could further develop to seedlings within or without light when inoculated the compatible fungi. However, light condition (12/12 h Light/Dark) produced the normal seedlings, while dark condition (0/24 h L/D) produced the abnormal seedlings. These may suggest that the development of young seedlings require light based on the effective symbiotic fungi. These findings will aid in seedling production of simulation-forestry ecology cultivation, conservation and reintroduction of Dendrobium.

Propagation and planting of containerized Eucalyptus seedlings in Hawaii

Treesearch

Gerald A. Walters

1983-01-01

A container reforestation system has been researched and developed in Hawaii which results in consistently high survival and growth rates for eucalyptus seedlings. Mean survival of containerized saligna eucalyptus (Eucalyptus saligna Smith) seedlings is 90 percent with a standard deviation of 4. Because transplant shock is minimal, seedlings begin to...

Fat Metabolism in Higher Plants XXVI. Biosynthesis of Fatty Acids in Tissues of Developing Seeds and Germinating Seedlings of Safflower (Carthamus tinctorius L.) 1

PubMed Central

McMahon, Vern; Stumpf, P. K.

1966-01-01

The capacity of both developing seeds and germinating seedlings of safflower for the incorporation of acetate-C14 into long-chain fatty acids is examined. Intact tissue of the developing seed shows a low rate of acetate incorporation into fatty acid initially but between the tenth and twenty-fifth day after flowering the tissue has a high rate of synthesis, in particular with respect to the unsaturated fatty acids. Centrifuged fractionation of homogenates of this developmental tissue yielded several active fractions, the most active being the PI fraction consisting mostly of plastids. Cofactor requirements and pH effects are examined. Germinating tissue shows a more uniform capacity for synthesis of fatty acids since there is no marked change in synthetic capacity. The newly synthesized fatty acids are consistently palmitic, stearic, and oleic acid. No linoleic synthesis could be detected. The most active fraction of cell-free preparation of germinating tissue is the plastid fraction (PI), similar to what was formed with developing tissue. PMID:5904587

Spatial and temporal regulation of the metabolism of reactive oxygen and nitrogen species during the early development of pepper (Capsicum annuum) seedlings.

PubMed

Airaki, Morad; Leterrier, Marina; Valderrama, Raquel; Chaki, Mounira; Begara-Morales, Juan C; Barroso, Juan B; del Río, Luis A; Palma, José M; Corpas, Francisco J

2015-09-01

The development of seedlings involves many morphological, physiological and biochemical processes, which are controlled by many factors. Some reactive oxygen and nitrogen species (ROS and RNS, respectively) are implicated as signal molecules in physiological and phytopathological processes. Pepper (Capsicum annuum) is a very important crop and the goal of this work was to provide a framework of the behaviour of the key elements in the metabolism of ROS and RNS in the main organs of pepper during its development. The main seedling organs (roots, hypocotyls and green cotyledons) of pepper seedlings were analysed 7, 10 and 14 d after germination. Activity and gene expression of the main enzymatic antioxidants (catalase, ascorbate-glutathione cycle enzymes), NADP-generating dehydrogenases and S-nitrosoglutathione reductase were determined. Cellular distribution of nitric oxide ((·)NO), superoxide radical (O2 (·-)) and peroxynitrite (ONOO(-)) was investigated using confocal laser scanning microscopy. The metabolism of ROS and RNS during pepper seedling development was highly regulated and showed significant plasticity, which was co-ordinated among the main seedling organs, resulting in correct development. Catalase showed higher activity in the aerial parts of the seedling (hypocotyls and green cotyledons) whereas roots of 7-d-old seedlings contained higher activity of the enzymatic components of the ascorbate glutathione cycle, NADP-isocitrate dehydrogenase and NADP-malic enzyme. There is differential regulation of the metabolism of ROS, nitric oxide and NADP dehydrogenases in the different plant organs during seedling development in pepper in the absence of stress. The metabolism of ROS and RNS seems to contribute significantly to plant development since their components are involved directly or indirectly in many metabolic pathways. Thus, specific molecules such as H2O2 and NO have implications for signalling, and their temporal and spatial regulation contributes to the success of seedling establishment. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Early survival and growth of planted shortleaf pine seedlings as a function of initial size and overstory stocking

Treesearch

John M. Kabrick; Daniel C. Dey; Stephen R. Shifley; Jason L. Villwock

2011-01-01

Shortleaf pine was once abundant throughout the Missouri Ozarks and there is renewed interest in its restoration. Past research suggested that the greatest survival and growth of shortleaf pine seedlings occurred where there was little competition for sunlight. This study, in the oak and oak-pine forests of the Sinkin Experimental Forest in southeastern Missouri,...

Germinant size of jack pine in relation to seed size and geographic origin

Treesearch

C.W. Yeatman

1966-01-01

The initial size of conifer seedlings is closely related to seed size (Hadders 1963), and seed size is a maternal characteristic that is highly subject to environmental modification (Mergen et al. 1964; Righter 1945). The effect of seed weight must be accounted for in critical studies of seedlings which attempt to attribute differences in growth to specific genetic or...

Establishment and Growth of Cherrybark Oak Seedlings Underplanted Beneath a Partial Overstory in a Minor Bottom of Southwestern Arkansas: First Year Results

Treesearch

Emile S. Gardiner; Jimmie L. Yeiser

1999-01-01

Advance regeneration is frequently inadequate to sufficiently restock the oak component of many bottomland stands, especially on productive sites with high levels of competition. We initiated a study near Beime, AR to examine the effects of pre-plant control of Japanese honeysuckle (Lonicera japonica Thunberg) and seedling quality on establishment...

Survival and growth of underplanted northern red oak on mesic sites in Eastern Tennessee: two-year results

Treesearch

Matthew G. Olson; Wayne K. Clatterbuck; Scott E. Schlarbaum

2006-01-01

As part of a replicated oak regeneration study initiated at the University of Tennessee’s Oak Ridge Forestry Experiment Station, 180 northern red oak (Quercus rubra L.) seedlings were allocated equally among three no-cut control stands, which provided an opportunity to chart the survival and growth of understory planted oak seedlings across several...

Nursery practices influence seedling morphology, field performance, and cost efficiency of containerized cherrybark oak.

Treesearch

Kirk D. Howell; Timothy B. Harrkngton

2004-01-01

To quantify effects of nursery practices on seedling cost and performance, cherrybark oaks (Quercus pagoda L.) were grown in three container sizes (170, 650, or 1,250 cm z) with or without fertilization and then planted Dec. 1995 at a site near Milledgeville, GA, with or without removal of container soil. Initial size, biomass, and leaf area of...

The endogenous hormones in soybean seedlings under the joint actions of rare earth element La(III) and ultraviolet-B stress.

PubMed

Peng, Qi; Zhou, Qing

2009-12-01

The dynamic state of endogenous hormone content in soybean seedlings was investigated for a further demonstration of alleviating the damage of the ultraviolet ultraviolet-B (UV-B) radiation in the La(III)-treated soybean seedlings under UV-B stress. Using hydroponics culture, the effects of lanthanum(III) on the contents of endogenous hormone under elevated ultraviolet-B radiation (280–320 nm) was studied. The results showed that the content of indole-3-acetic acid (IAA) in soybean seedlings decreased initially and then increased when the seedlings underwent UV-B treatment during the stress and convalescent period; this was compared with a control; acetic acid oxidase (IAAO) activity increased at first (first to fifth day) and then decreased (sixth to 11th day). A similar change of abscisic acid content and IAAO content in soybean seedlings occurred; gibberellic acid (GA) content decreased during the experiment compared with control. The content of IAA and GA in soybean seedlings with La(III) + UV-B treatment was higher than those of UV-B treatment; IAAO activity and GA content in soybean seedlings with La (III) + UV-B treatment were lower than those of UV-B treatment. It suggested that the regulative effect of La(III) at the optimum concentration on endogenous hormone improved the ability of plant stress resistance, and its protective effect against low UV-B radiation was superior to high UV-B radiation. The defensive effect of La(III) on soybean seedlings under UV-B stress was carried out on the layer of defense system.

Identification of seedling vigor-associated quantitative trait loci in temperate japonica rice

USDA-ARS?s Scientific Manuscript database

A quantitative trait loci (QTL) analysis of seedling vigor traits was conducted under dry-seeded conditions using 176 recombinant inbred lines developed from a cross of two California temperate japonica rice varieties M-203 and M-206. Height at early seedling (HES) and late seedling (HLS) stage, gro...

Proceedings of the Southern Containerized Forest Tree Seedling Conference

Treesearch

James P. Barnett; [Editors

1982-01-01

Research findings provide benefits to society when they are communicated to and implemented by users. This principle was the rationale for the Southern Containerized Forest Tree Seedling Conference. In the 8 years since the North American Containerized Forest Tree Seedling Symposium in August 1974, southern foresters have developed container seedling nurseries and...

Photosynthetic light response of flooded cherrybark oak (Quercus pagoda) seedlings grown in two light regimes

Treesearch

Emile S. Gardiner; Ken W. Krauss

2001-01-01

Two-year-old cherrybark oak (Quercus pagoda Raf.) seedlings raised in full or partial (27 percent) sunlight were flooded for 30 days to study the effects of light availability and root inundation on photosynthetic light response. Compared with seedlings receiving full sunlight, seedlings receiving partial sunlight developed leaves...

Expression of stress-related genes in zebrawood (Astronium fraxinifolium, Anacardiaceae) seedlings following germination in microgravity

PubMed Central

Inglis, Peter W.; Ciampi, Ana Y.; Salomão, Antonieta N.; Costa, Tânia da S.A.; Azevedo, Vânia C.R.

2014-01-01

Seeds of a tropical tree species from Brazil, Astronium fraxinifolium, or zebrawood, were germinated, for the first time in microgravity, aboard the International Space Station for nine days. Following three days of subsequent growth under normal terrestrial gravitational conditions, greater root length and numbers of secondary roots was observed in the microgravity-treated seedlings compared to terrestrially germinated controls. Suppression subtractive hybridization of cDNA and EST analysis were used to detect differential gene expression in the microgravity-treated seedlings in comparison to those initially grown in normal gravity (forward subtraction). Despite their return to, and growth in normal gravity, the subtracted library derived from microgravity-treated seedlings was enriched in known microgravity stress-related ESTs, corresponding to large and small heat shock proteins, 14-3-3-like protein, polyubiquitin, and proteins involved in glutathione metabolism. In contrast, the reverse-subtracted library contained a comparatively greater variety of general metabolism-related ESTs, but was also enriched for peroxidase, possibly indicating the suppression of this protein in the microgravity-treated seedlings. Following continued growth for 30 days, higher concentrations of total chlorophyll were detected in the microgravity-exposed seedlings. PMID:24688295

Is There a Role for the Apex in Shoot Geotropism?

PubMed Central

Hart, James W.; Macdonald, Ian R.

1984-01-01

Experiments with horizontal etiolated sunflower (Helianthus annuus L.) seedlings supported centrally such that both apical and basal ends are free to react to geostimulus, revealed that the apical end commences curvature 1 to 2 hours earlier than the basal end. The later curvature in the basal region is a consequence of the absence of growth in the initial period rather than merely slower growth. A comparison of zonal growth rates in a vertical and a horizontal seedling confirmed that geostimulus induces a renewal of growth in a region where growth had ceased. Removing the apical half of the hypocotyl showed that the curvature resulting from this growth initiation in the basal region is dependent on attachment to the apical region. Evidence that this dependence is unlikely to be due to energy deficiency is adduced. The prior response of the apical end to geostimulus and the apically dependent later initiation of new growth in the basal region are compatible with the delay inherent in message transport from apex to base and are considered as evidence for apical involvement in the totality of the seedling's georesponse. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:16663410

Uptake of Seeds Secondary Metabolites by Virola surinamensis Seedlings

PubMed Central

Kato, Massuo Jorge; Yoshida, Massayoshi; Lopes, Norberto Peporine; da Silva, Denise Brentan; Cavalheiro, Alberto José

2012-01-01

The major secondary metabolites and fatty acids occurring in the seeds of Virola surinamensis were monitored by GC-MS during germination and seedling development. The role as carbon source for seedling development was indicated considering that both classes of compounds were similarly consumed in the seeds and that no selective consumption of compounds could be detected. PMID:22505921

Tree seedling response to LED spectra: Implications for forest restoration

Treesearch

Antonio Montagnoli; R. Kasten Dumroese; Mattia Terzaghi; Jeremiah R. Pinto; Nicoletta Fulgaro; Gabriella Stefania Scippa; Donato Chiatante

2018-01-01

We found that different spectra, provided by light-emitting diodes or a fluorescent lamp, caused different photomorphological responses depending on tree seedling type (coniferous or broad-leaved), species, seedling development stage, and seedling fraction (shoot or root). For two conifers (Picea abies and Pinus sylvestris) soon after germination (≤40 days), more...

Density and Age Affect Performance of Containerized Loblolly Pine Seedlings

Treesearch

James P. Barnett

1980-01-01

Loblolly pine seedlings were grown in 1 x 5 inch biodegradable plastic tubes for 10, 12, and 14 weeks at densities of 42, 84, 126, and 168 per square foot. Seedling density and age significantly affected seedling development at time of outplanting, and density became more important as greenhouse growing times increased. All morphological characteristics measured when...

Growth strategies and threshold responses to water deficit modulate effects of warming on tree seedlings from forest to alpine

USGS Publications Warehouse

Lazarus, Brynne E.; Castanha, Cristina; Germino, Matthew; Kueppers, Lara M.; Moyes, Andrew B.

2018-01-01

1.Predictions of upslope range shifts for tree species with warming are based on assumptions of moisture stress at lower elevation limits and low temperature stress at high elevation limits. However, recent studies have shown that warming can reduce tree seedling establishment across the entire gradient from subalpine forest to alpine via moisture limitation. Warming effects also vary with species, potentially resulting in community shifts in high elevation forests. 2.We examined the growth and physiology underlying effects of warming on seedling demographic patterns. We evaluated dry mass (DM), root length, allocation above- and belowground, and relative growth rate (RGR) of whole seedlings, and their ability to avoid or endure water stress via water-use efficiency and resisting turgor loss, for Pinus flexilis, Picea engelmannii and Pinus contorta seeded below, at, and above treeline in experimentally warmed, watered, and control plots in the Rocky Mountains, USA. We expected that growth and allocation responses to warming would relate to moisture status and that variation in drought tolerance traits would explain species differences in survival rates. 3.Across treatments and elevations, seedlings of all species had weak turgor-loss resistance, and growth was marginal with negative RGR in the first growth phase (-0.01 to -0.04 g/g/d). Growth was correlated with soil moisture, particularly in the relatively small-seeded P. contorta and P. engelmannii. P. flexilis, known to have the highest survivorship, attained the greatest DM and longest root but was also the slowest growing and most water-use-efficient. This was likely due to its greater reliance on seed reserves. Seedlings developed 15% less total DM, 25% less root DM, and 11% shorter roots in heated compared to unheated plots. Higher temperatures slightly increased DM, root length and RGR where soils were wettest, but more strongly decreased these variables under drier conditions. 4.Synthesis: The surprising heat-inhibition of tree seedling establishment at the cold edge of forests appears to have a physiological basis: newly germinated seedlings have poor moisture stress tolerance, which appears related to marginal initial growth and heavy reliance on seed reserves. Variation in these attributes among tree species at treeline helps explain their different climate responses.

Growth and development in higher plants under simulated microgravity conditions on a 3-dimensional clinostat.

PubMed

Shimazu, T; Yuda, T; Miyamoto, K; Yamashita, M; Ueda, J

2001-01-01

Growth and development of etiolated pea (Pisum sativum L. cv. Alaska) and maize (Zea mays L. cv. Golden Cross Bantam) seedlings grown under simulated microgravity conditions were intensively studied using a 3-dimensional clinostat as a simulator of weightlessness. Epicotyls of etiolated pea seedlings grown on the clinostat were the most oriented toward the direction far from cotyledons. Mesocotyls of etiolated maize seedlings grew at random and coleoptiles curved slightly during clinostat rotation. Clinostat rotation promoted the emergence of the 3rd internodes in etiolated pea seedlings, while it significantly inhibited the growth of the 1st internodes. In maize seedlings, the growth of coleoptiles was little affected by clinostat rotation, but that of mesocotyls was suppressed, and therefore, the emergence of the leaf out of coleoptile was promoted. Clinostat rotation reduced the osmotic concentration in the 1st internodes of pea seedlings, although it has little effect on the 2nd and the 3rd internodes. Clinostat rotation also reduced the osmotic concentrations in both coleoptiles and mesocotyls of maize seedlings. Cell-wall extensibilities of the 1st and the 3rd internodes of pea seedlings grown on the clinostat were significantly lower and higher as compared with those on 1 g conditions, respectively. Cell-wall extensibility of mesocotyls in seedlings grown on the clinostat also decreased. Changes in cell wall properties seem to be well correlated to the growth of each organ in pea and maize seedlings. These results suggest that the growth and development of plants is controlled under gravity on earth, and that the growth responses of higher plants to microgravity conditions are regulated by both cell-wall mechanical properties and osmotic properties of stem cells. c 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Light Is More Important Than Nutrient Ratios of Fertilization for Cymodocea nodosa Seedling Development.

PubMed

Alexandre, Ana; Silva, João; Santos, Rui

2018-01-01

Restoration of seagrass beds through seedlings is an alternative to the transplantation of adult plants that reduces the impact over donor areas and increases the genetic variability of restored meadows. To improve the use of Cymodocea nodosa seedlings, obtained from seeds germinated in vitro , in restoration programs, we investigated the ammonium and phosphate uptake rates of seedlings, and the synergistic effects of light levels (20 and 200 μmol quanta m -2 s -1 ) and different nitrogen to phosphorus molar ratios (40 μM N:10 μM P, 25 μM N:25 μM P, and 10 μM N:40 μM P) on the photosynthetic activity and growth of seedlings. The nutrient content of seedlings was also compared to the seed nutrient reserves to assess the relative importance of external nutrient uptake for seedling development. Eighty two percent of the seeds germinated after 48 days at a mean rate of 1.5 seeds per day. All seedlings under all treatments survived and grew during the 4 weeks of the experiment. Seedlings of C. nodosa acquired ammonium and phosphate from the incubation media while still attached to the seed, at rates of about twice of adult plants. The relevance of external nutrient uptake was further highlighted by the observation that seedlings' tissues were richer in nitrogen and phosphorus than non-germinated seeds. The uptake of ammonium followed saturation kinetics with a half saturation constant of 32 μM whereas the uptake of phosphate increased linearly with nutrient concentration within the range tested (5 - 100 μM). Light was more important than the nutrient ratio of fertilization for the successful development of the young seedlings. The seedlings' photosynthetic and growth rates were about 20% higher in the high light treatment, whereas different nitrogen to phosphorus ratios did not significantly affect growth. The photosynthetic responses of the seedlings to changes in the light level and their capacity to use external nutrient sources showed that seedlings of C. nodosa have the ability to rapidly acclimate to the surrounding light and nutrient environment while still attached to the seeds. C. nodosa seedlings experiencing fertilization under low light levels showed slightly enhanced growth if nourished with a balanced formulation, whereas a slight increase in growth was also observed with unbalanced formulations under a higher light level. Our results highlight the importance of high light availability at the seedling restoration sites.

Growth of Douglas-fir seedlings after slash burning.

Treesearch

Robert F. Tarrant; Ernest. Wright

1955-01-01

An understanding of the ways slash burning may affect seedling growth is important in evaluating present slash-disposal practices. Some observations of early seedling development after slash burning are now available from a recent exploratory study.

Antioxidant capacity of flavonoid in soybean seedlings under the joint actions of rare earth element La(III) and ultraviolet-B stress.

PubMed

Peng, Qi; Zhou, Qing

2009-01-01

The dynamic state of antioxidant capacity of flavonoid was investigated for a further demonstration of alleviating the damage of the ultraviolet (UV)-B radiation in the La-treated soybean seedlings under UV-B stress. Using hydroponics culture, the effects of lanthanum on the contents of flavonoid and its ability of antioxidant under elevated ultraviolet-B radiation (280-320 nm) was studied. The results showed flavonoid content in soybean seedlings with UV-B treatment during the stress and convalescent period was increased initially and then decreased, compared with control. Membrane permeability and MDA contents increase at first (first to fifth day) and then decrease (6th-11th day). A similar change of flavonoid content and clearance of flavonoid scavenging O2- and *OH in soybean seedlings occurred. Flavonoid content and ability of flavonoid scavenging O2- and *OH in soybean seedlings with La(III) + UV-B treatment were higher than those of UV-B treatment. Meanwhile, membrane permeability and MDA contents in soybean seedlings were lower than those of UV-B treatment. Compared with control, phenylalanine content in soybean seedlings with UV-B treatment is depressed, phenylalanine content in soybean seedlings with La(III) treatment was enhanced. However, phenylalanine content in La(III) + UV-B treatment is not decreased but slightly increased, compared with UV-B treatment. It suggested that the regulative effect of La(III) of the optimum concentration on flavonoid improved the metabolism of ROS, diminished the concentration of MDA and maintained normal plasma membrane permeability, and that its protective effect against low UV-B radiation is superior to that of high UV-B radiation. The defensive effect of La(III) on soybean seedlings under UV-B stress is carried out on the layer of defense system.

Two genetically separable phases of growth inhibition induced by blue light in Arabidopsis seedlings

NASA Technical Reports Server (NTRS)

Parks, B. M.; Cho, M. H.; Spalding, E. P.; Evans, M. L. (Principal Investigator)

1998-01-01

High fluence-rate blue light (BL) rapidly inhibits hypocotyl growth in Arabidopsis, as in other species, after a lag time of 30 s. This growth inhibition is always preceded by the activation of anion channels. The membrane depolarization that results from the activation of anion channels by BL was only 30% of the wild-type magnitude in hy4, a mutant lacking the HY4 BL receptor. High-resolution measurements of growth made with a computer-linked displacement transducer or digitized images revealed that BL caused a rapid inhibition of growth in wild-type and hy4 seedlings. This inhibition persisted in wild-type seedlings during more than 40 h of continuous BL. By contrast, hy4 escaped from the initial inhibition after approximately 1 h of BL and grew faster than wild type for approximately 30 h. Wild-type seedlings treated with 5-nitro-2-(3-phenylpropylamino)-benzoic acid, a potent blocker of the BL-activated anion channel, displayed rapid growth inhibition, but, similar to hy4, these seedlings escaped from inhibition after approximately 1 h of BL and phenocopied the mutant for at least 2.5 h. The effects of 5-nitro-2-(3-phenylpropylamino)-benzoic acid and the HY4 mutation were not additive. Taken together, the results indicate that BL acts through HY4 to activate anion channels at the plasma membrane, causing growth inhibition that begins after approximately 1 h. Neither HY4 nor anion channels appear to participate greatly in the initial phase of inhibition.

Development of In Vitro Systems for Switchgrass (Panicum virgatum) - Final Report for 1992 to 2002

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conger, B.V.

2003-01-16

Our project began on July 1, 1992, with the objective of developing systems that could be used in biotechnological approaches to switchgrass improvement. Within six months after initiation of the project, we had worked out protocols in which plants could be regenerated from callus cultures through both organogenesis and somatic embryogenesis. Documentation for both modes of regeneration was provided in our progress reports and in publications. One thousand regenerated plants were established in the field during the first year. We found that Alamo (lowland type) was much more amenable to in vitro culture, and plants could be regenerated much moremore » easily than from Cave-in-Rock (upland type). During the first three years of the project, we studied the influence of genotype, culture medium components, explant type, etc., on regeneration. As mentioned, we found that the lowland cultivars Alamo and Kanlow were much easier to regenerate than upland cultivars, such as Trailblazer, Blackwell, and Cave-in-Rock. For callus induction, we initially used mature caryopses, young leaf tissue, and portions of seedlings. We were successful in inducing callus and regenerating plants from all explants. Two other systems developed during the 4th to 6th year period of the project included multiple shoot formation initiated from germinated seedlings and regenerable suspension cultures. The latter were initiated from embryogenic calluses produced from in vitro developed inflorescences. An important factor for producing multiple shoots was the presence of thidiazuron in the medium. The shoots could be easily rooted and numerous plantlets produced. The last 3 to 4 years of the project focused on anther and microspore culture experiments to produce haploid plants and on genetic transformation. Although thousands of putative haploid plants were produced from a few anthers, they were very weak and difficult to keep alive. Chromosome counts revealed the gametic number in cells where it was possible to count chromosomes. The isolated microspore culture experiments were not successful.« less

A comparison of the effects of different shelterwood harvest methods on the survival and growth of acorn-origin oak seedlings

Treesearch

Patrick H. Brose

2011-01-01

Timely development of newly germinated oak (Quercus spp.) seedlings into competitive-sized regeneration is an essential part of the oak regeneration process. The amount of sunlight reaching the forest floor partly governs this development, and foresters often use the shelterwood system to expose oak seedlings to varying degrees of insolation. To...

Seedling mortality and development of root rot in white pine seedlings in two bare-root nurseries

Treesearch

J. Juzwik; D. J. Rugg

1996-01-01

Seedling mortality and development of root rot in white pine (Pinus strobus) were followed across locations and over time within three operational nursery fields with loamy sand soils at a provincial nursery in southwestern Ontario, Canada, and a state nursery in southern Wisconsin, USA. One Ontario field was fumigated with dazomet; the other was not...

Synthesis of ectomycorrhizae on northern red oak seedlings in a Michigan nursery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dixon, R.K.; Johnson, P.S.

1993-01-01

Vegetative inoculum of the ectomycorrhizal fungus Suillus luteus was thoroughly mixed into fumigated nursery soil, and northern red oak seedlings of four families were evaluated one and two years after sowing for ectomycorrhizal development, growth, and nutrition. At the end of year one, treated seedlings were successfully inoculated with S. luteus, but the percentage varied significantly with family. Suillus luteus persisted on lateral roots two years following sowing. Two of four seedling families inoculated with S. luteus were significantly larger in size than control plants. These results suggest that the fungal symbiont S. luteus can be successfully introduced into nurseriesmore » and that early ectomycorrhizal development improves the growth of northern red oak seedlings.« less

Analysis of peg formation in cucumber seedlings grown on clinostats and in a microgravity (space) environment.

PubMed

Link, B M; Cosgrove, D J

1999-12-01

In young cucumber seedlings, the peg is a polar out-growth of tissue that functions by snagging the seed coat, thereby freeing the cotyledons. Previous studies have indicated that peg formation is gravity dependent. In this study we analyzed peg formation in cucumber seedlings (Cucumis sativus L. cv Burpee Hybrid II) grown under conditions of normal gravity, microgravity, and simulated microgravity (clinostat rotation). Seeds were germinated on the ground, in clinostats and on board the space shuttle (STS 95) for 1-2 days, frozen and subsequently examined for their stage of development, degree of hook formation, number of pegs formed, and peg morphology. The frequency of peg formation in space grown seedlings was found to be nearly identical to that of clinostat grown seedlings and to differ from that of seedlings germinated under normal gravity only in a minority of cases; approximately 6% of the seedlings formed two pegs and nearly 2% of the seedlings lacked pegs, whereas such abnormalities did not occur in ground controls. The degree of hook formation was found to be less pronounced for space grown seedlings, compared to clinostat grown seedlings, indicating a greater degree of decoupling between peg formation and hook formation in space. Nonetheless, in all seedlings having single pegs and a hook, the peg was found to be positioned correctly on the inside of the hook, showing that there is coordinate development even in microgravity environments. Peg morphologies were altered in space grown samples, with the pegs having a blunt appearance and many pegs showing alterations in expansion, with the peg extending out over the edges of the seed coat and downwards. These phenotypes were not observed in clinostat or ground grown seedlings.

Analysis of peg formation in cucumber seedlings grown on clinostats and in a microgravity (space) environment

NASA Technical Reports Server (NTRS)

Link, B. M.; Cosgrove, D. J.

1999-01-01

In young cucumber seedlings, the peg is a polar out-growth of tissue that functions by snagging the seed coat, thereby freeing the cotyledons. Previous studies have indicated that peg formation is gravity dependent. In this study we analyzed peg formation in cucumber seedlings (Cucumis sativus L. cv Burpee Hybrid II) grown under conditions of normal gravity, microgravity, and simulated microgravity (clinostat rotation). Seeds were germinated on the ground, in clinostats and on board the space shuttle (STS 95) for 1-2 days, frozen and subsequently examined for their stage of development, degree of hook formation, number of pegs formed, and peg morphology. The frequency of peg formation in space grown seedlings was found to be nearly identical to that of clinostat grown seedlings and to differ from that of seedlings germinated under normal gravity only in a minority of cases; approximately 6% of the seedlings formed two pegs and nearly 2% of the seedlings lacked pegs, whereas such abnormalities did not occur in ground controls. The degree of hook formation was found to be less pronounced for space grown seedlings, compared to clinostat grown seedlings, indicating a greater degree of decoupling between peg formation and hook formation in space. Nonetheless, in all seedlings having single pegs and a hook, the peg was found to be positioned correctly on the inside of the hook, showing that there is coordinate development even in microgravity environments. Peg morphologies were altered in space grown samples, with the pegs having a blunt appearance and many pegs showing alterations in expansion, with the peg extending out over the edges of the seed coat and downwards. These phenotypes were not observed in clinostat or ground grown seedlings.

[Status of traditional Chinese medicine materials seed and seedling breeding bases].

PubMed

Li, Ying; Huang, Lu-Qi; Zhang, Xiao-Bo; Wang, Hui; Cheng, Meng; Zhang, Tian; Yang, Guang

2017-11-01

Seeds and seedlings are the material basis of traditional Chinese medicine materials production, and the construction of traditional Chinese medicine materials seed and seedling breeding bases is beneficial to the production of high-quality traditional Chinese medicine materials. The construction of traditional Chinese medicine materials seed and seedling breeding bases is one of the major topics of Chinese medica resources census pilot. Targets, tasks of traditional Chinese medicine materials seed and seedling breeding bases based on Chinese medica resources census pilot were expounded.Construction progress including hardware construction, germplasm conservation and breeding, procedures and standardsestablishment, social servicesare presented. Development counter measures were proposed for the next step: perfect the standard and system, maintain and strengthen the breeding function, strengthen the cultivation of multi-level talents, explore market development model, joint efforts to deepen services and development. Copyright© by the Chinese Pharmaceutical Association.

Initial Response of Pine Seedlings and Weeds to Dried Sewage Sludge in Rehabilitation of an Eroded Forest Site

Treesearch

Charles R. Berry

1977-01-01

Dried sewage sludge was applied at rates of 0, 17, 34, and 69 metric tons/ha on a badly eroded forest site in the Piedmont region of northeast Georgia. Production of weed bio mass varied directly with amount of sludge applied. Heigh growth for both shortleafand loblolly pine seedlings appeared to be greater on plots receiving 17 metric tons of sludge/ha, bu differences...

Response of different-aged black cherry trees to ambient ozone exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fredericksen, T.S.; Joyce, B.J.; Kouterick, K.B.

1994-06-01

Black cherry (Prunus serotina Ehrh.) is a valuable commercial timber species which is also highly sensitive to ozone relative to other eastern deciduous tree species. Studies of ozone effects on forest trees have been restricted mostly to experiments using small seedlings under controlled conditions. Yet, mature trees may differ from seedlings in physiology, morphology, and exposure to air pollutants. An experiment was conducted in 1993 to determine differences in ozone uptake and foliar injury symptoms between open-ground seedlings, forest saplings, and mature forest trees of black cherry in northcentral Pennsylvania. Seedlings grew under the highest ozone concentrations and also hadmore » greater seasonal ozone uptake due to higher rates of stomatal conductance. However, because of their indeterminate growth habit, seedlings had lower cumulative ozone uptake per leaf lifespan than saplings or mature trees, both of which had determinate shoot growth. Although greater initially for seedlings, foliar injury was nearly identical between size classes by the end of the growing season. Leaves in the lower crown of larger trees had lower ozone uptake than leaves in the upper crown, but exhibited more foliar injury symptoms. Lower crown leaves received more effective exposure to ozone because of their thinner leaves and had less available photosynthate for repair or replacement of damaged tissue.« less

Combined effects of lead and acid rain on photosynthesis in soybean seedlings.

PubMed

Hu, Huiqing; Wang, Lihong; Liao, Chenyu; Fan, Caixia; Zhou, Qing; Huang, Xiaohua

2014-10-01

To explore how lead (Pb) and acid rain simultaneously affect plants, the combined effects of Pb and acid rain on the chlorophyll content, chlorophyll fluorescence reaction, Hill reaction rate, and Mg(2+)-ATPase activity in soybean seedlings were investigated. The results indicated that, when soybean seedlings were treated with Pb or acid rain alone, the chlorophyll content, Hill reaction rate, Mg(2+)-ATPase activity, and maximal photochemical efficiency (F(v)/F(m)) were decreased, while the initial fluorescence (F 0) and maximum quantum yield (Y) were increased, compared with those of the control. The combined treatment with Pb and acid rain decreased the chlorophyll content, Hill reaction rate, Mg(2+)-ATPase activity, F(v)/F(m), and Y and increased F 0 in soybean seedlings. Under the combined treatment with Pb and acid rain, the two factors showed additive effects on the chlorophyll content in soybean seedlings and exhibited antagonistic effects on the Hill reaction rate. Under the combined treatment with high-concentration Pb and acid rain, the two factors exhibited synergistic effects on the Mg(2+)-ATPase activity, F 0, F v/F m, as well as Y. In summary, the inhibition of the photosynthetic process is an important physiological basis for the simultaneous actions of Pb and acid rain in soybean seedlings.

Application of arbuscular mycorrhizal fungi with Pseudomonas aeruginosa UPMP3 reduces the development of Ganoderma basal stem rot disease in oil palm seedlings.

PubMed

Sundram, Shamala; Meon, Sariah; Seman, Idris Abu; Othman, Radziah

2015-07-01

The effect of arbuscular mycorrhizal fungi (AMF) in combination with endophytic bacteria (EB) in reducing development of basal stem rot (BSR) disease in oil palm (Elaeis guineensis) was investigated. BSR caused by Ganoderma boninense leads to devastating economic loss and the oil palm industry is struggling to control the disease. The application of two AMF with two EB as biocontrol agents was assessed in the nursery and subsequently, repeated in the field using bait seedlings. Seedlings pre-inoculated with a combination of Glomus intraradices UT126, Glomus clarum BR152B and Pseudomonas aeruginosa UPMP3 significantly reduced disease development measured as the area under disease progression curve (AUDPC) and the epidemic rate (R L) of disease in the nursery. A 20-month field trial using similar treatments evaluated disease development in bait seedlings based on the rotting area/advancement assessed in cross-sections of the seedling base. Data show that application of Glomus intraradices UT126 singly reduced disease development of BSR, but that combination of the two AMF with P. aeruginosa UPMP3 significantly improved biocontrol efficacy in both nursery and fields reducing BSR disease to 57 and 80%, respectively. The successful use of bait seedlings in the natural environment to study BSR development represents a promising alternative to nursery trial testing in the field with shorter temporal assessment.

Effect of seedling stock on the early stand development and physiology of improved loblolly pine (Pinus taeda L.) seedlings

Treesearch

Shakuntala Sharma; Joshua P. Adams; Jamie L. Schuler; Robert L. Ficklin; Don C. Bragg

2016-01-01

This study assessed the effects of spacing and genotype on the growth and physiology of improved loblolly pine (Pinus taeda L.) seedlings from three distinct genotypes planted in Drew County, Arkansas (USA). Genotype had a significant effect on survival and height. Clone CF Var 1 showed greater height and survival compared to other seedlings....

Survival and Growth of Northern Red Oak Seedlings Following a Prescribed Burn

Treesearch

Paul S. Johnson

1974-01-01

Mortality of northern red oak seedlings in a spring prescribed burn was related to temperature near the root collar. Most of the 42 percent of seedlings that survived the burn developed new shoots from the root collar.

Effect of apical meristem clipping on carbon allocation and morphological development of white oak seedlings

Treesearch

Paul P. Kormanik; Shi-Jean S. Sung; T.L. Kormanik; Stanley J. Zarnoch

1994-01-01

Seedlings from three open-pollinated half-sib white oak seedlots were clipped in mid-July and their development was compared to nonclipped controls after one growing season.In general when data were analyzed by family, clipped seedlings were significantly less desirable in three to six of the eight variables tested.Numerically, in all families seedlots, the clipped...

Germination and seedling development

USDA-ARS?s Scientific Manuscript database

Cottonseed germination and seedling development are highly sensitive to the environment at planting and for several weeks after that. Major factors that affect germination and development are temperature, water availability, soil conditions such as compaction, rhizosphere gases, and seed and seedlin...

Macronutrient deficiency symptoms in seedlings of four northern hardwoods.

Treesearch

Gayne G. Erdmann; Frederick T. Metzger; Robert R. Oberg

1979-01-01

Illustrates and describes the visual deficiency symptoms for N, P, K, Ca, Mg, and S in sugar maple, red maple, white ash, and paper birch seedlings. Effects of these deficiencies on the development and nutrient composition of seedlings are also examined.

Kinetics for phototropic curvature by etiolated seedlings of Arabidopsis thaliana

NASA Technical Reports Server (NTRS)

Orbovic, V.; Poff, K. L.

1991-01-01

An infrared-imaging system has been used to study the influence of gravity on the kinetics of first positive phototropism. The development of phototropic curvature of etiolated seedlings of Arabidopsis thaliana was measured in the absence of visible radiation. Following a pulse of blue light, stationary seedlings curved to a maximum of approximately 16 degrees about 80 minutes after stimulation. The seedlings then curved upward again or straightened by about 6 degrees during the subsequent 100 minutes. Seedlings rotated on a clinostat reached a similar maximum curvature following photostimulation. These seedlings maintained that curvature for 30 to 40 minutes before subsequently straightening to the same extent as the stationary seedlings. It is concluded that straightening is not a consequence of gravitropism, although gravity has some effect on the phototropism kinetics.

A rapid inoculation technique for assessing pathogenicity of Fusarium oxysporum f. sp. niveum and F. o. melonis on Cucurbits

USGS Publications Warehouse

Freeman, S.; Rodriguez, R.J.

1993-01-01

A continuous-dip inoculation technique for rapid assessment of pathogenicity of Fusarium oxysporum f. sp. niveum and F. o. melonis was developed. The method, adapted from a similar procedure for determining pathogenicity of Colletotrichum magna (causal agent of anthracnose of cucurbits), involves constant exposure of seedlings and cuttings (seedlings with root systems excised) of watermelon and muskmelon to conidial suspensions contained in small scintillation vials. Disease development in intact seedlings corresponded well to disease responses observed with the standard root-dip inoculation/pot assay. The continuous-dip inoculation technique resulted in rapid disease development, with 50% of watermelon cuttings dying after 4–6 days of exposure to F. o. niveum. A mortality of 30% also was observed in watermelon cuttings exposed to conidia of F. o. melonis, as opposed to only a 0–2.5% mortality in seedlings with intact roots. Disease response was similar with muskmelon seedlings and cuttings continuously dip-inoculated with F. o. melonis isolates. However, no disease symptoms were observed in muskmelon seedlings or cuttings inoculated with F. o. niveum. Four nonpathogenic isolates of F. oxysporum did not cause disease symptoms in either watermelon or muskmelon cuttings and seedlings when assayed by this technique. The proposed method enables a rapid screening of pathogenicity and requires less time, labor, and greenhouse space than the standard root-dip inoculation/pot assay. The reliability of the continuous-dip inoculation technique is limited, however, to exposure of intact seedlings at a concentration of 1 × 106conidia per milliliter; the method is not accurate at this range for excised seedlings.

The role of the storage carbon of cotyledons in the establishment of seedlings of Hymenaea courbaril under different light conditions.

PubMed

Santos, Henrique P; Buckeridge, Marcos S

2004-12-01

Hymenaea courbaril (Leguminosae-Caesalpinioideae) is a tree species with wide distribution through all of the Neotropics. It has large seeds (approx. 5 g) with non-photosynthetic storage cotyledons rich (40 %) in a cell wall polysaccharide (xyloglucan) as a carbon reserve. Because it is found in the understorey of tropical forests, it has been considered as a shade-tolerant, late-secondary species. However, the physiological mechanisms involved in seedling establishment, especially regarding the interplay between storage and light intensity, are not understood. In this work, the ecophysiological role of this carbon cotyledon reserve (xyloglucan) is characterized, emphasizing its effects on seedling growth and development during the transition from heterotrophy to autotrophy under different light conditions. Seedlings of H. courbaril were grown in environments with different light intensities, and with or without cotyledons detached before xyloglucan mobilization. Development, growth, photosynthesis and carbon partitioning (dry mass and [14C]sucrose) were analysed in each treatment. The detachment of cotyledons was not important for seedling survival, but resulted in a strong restriction (50 % less) of shoot growth, which was the main sink for the cotyledon carbon reserves. Carbon restriction promoted an early maturation of the photosynthetic apparatus without changes in the net CO2 fixation per unit area. The reduced surface area of the first leaves in seedlings without cotyledons was evidence of limited growth and development of seedlings in low light conditions (22 micromol m(-2) s(-1) photon flux). There is an increase in the importance of storage xyloglucan in cotyledons for H. courbaril seedling development as light intensity decreases, confirming that this polymer plays a key role in the adaptation of this species to establish successfully in the shadowed understorey of the forest.

Comparative seed germination and seedling development of the ghost orchid, Dendrophylax lindenii (Orchidaceae), and molecular identification of its mycorrhizal fungus from South Florida

PubMed Central

Hoang, Nguyen H.; Kane, Michael E.; Radcliffe, Ellen N.; Zettler, Lawrence W.; Richardson, Larry W.

2017-01-01

Background and Aims The endangered leafless ghost orchid, Dendrophylax lindenii, one of the most renowned orchids in the world, is difficult to grow under artificial conditions. Published information on asymbiotic and symbiotic (co-culture with a mycobiont) seed germination, seedling anatomy and developmental morphology of this leafless orchid is completely lacking. This information is critical for the development of efficient procedures for ghost orchid production for successful reintroduction. Methods Ghost orchid seedling early development stages were morphologically and anatomically defined to compare germination, embryo and protocorm maturation and seedling development during asymbiotic and symbiotic culture with one of two mycorrhizal strains (Dlin-379 and Dlin-394) isolated from ghost orchid roots in situ. Key Results Seeds symbiotically germinated at higher rates when cultured with fungal strain Dlin-394 than with strain Dlin-379 or asymbiotically on P723 medium during a 10-week culture period. Fungal pelotons were observed in protocorm cells co-cultured with strain Dlin-394 but not Dlin-379. Some 2-year-old seedlings produced multinode inflorescences in vitro. Production of keikis from inflorescence nodes indicated the capacity for clonal production in the ghost orchid. Conclusions Ghost orchid embryo and seedling development were characterized into seven stages. Fungal strain Dlin-394 was confirmed as a possible ghost orchid germination mycobiont, which significantly promoted seed germination and seedling development. Internal transcribed spacer sequencing data confirmed that Dlin-394 belongs within the genus Ceratobasidium. These results offer the opportunity to examine the benefits of using a mycobiont to enhance in vitro germination and possibly ex vitro acclimatization and sustainability following outplanting. PMID:28025292

Comparative seed germination and seedling development of the ghost orchid, Dendrophylax lindenii (Orchidaceae), and molecular identification of its mycorrhizal fungus from South Florida.

PubMed

Hoang, Nguyen H; Kane, Michael E; Radcliffe, Ellen N; Zettler, Lawrence W; Richardson, Larry W

2017-02-01

The endangered leafless ghost orchid, Dendrophylax lindenii, one of the most renowned orchids in the world, is difficult to grow under artificial conditions. Published information on asymbiotic and symbiotic (co-culture with a mycobiont) seed germination, seedling anatomy and developmental morphology of this leafless orchid is completely lacking. This information is critical for the development of efficient procedures for ghost orchid production for successful reintroduction. Ghost orchid seedling early development stages were morphologically and anatomically defined to compare germination, embryo and protocorm maturation and seedling development during asymbiotic and symbiotic culture with one of two mycorrhizal strains (Dlin-379 and Dlin-394) isolated from ghost orchid roots in situ KEY RESULTS: Seeds symbiotically germinated at higher rates when cultured with fungal strain Dlin-394 than with strain Dlin-379 or asymbiotically on P723 medium during a 10-week culture period. Fungal pelotons were observed in protocorm cells co-cultured with strain Dlin-394 but not Dlin-379. Some 2-year-old seedlings produced multinode inflorescences in vitro Production of keikis from inflorescence nodes indicated the capacity for clonal production in the ghost orchid. Ghost orchid embryo and seedling development were characterized into seven stages. Fungal strain Dlin-394 was confirmed as a possible ghost orchid germination mycobiont, which significantly promoted seed germination and seedling development. Internal transcribed spacer sequencing data confirmed that Dlin-394 belongs within the genus Ceratobasidium These results offer the opportunity to examine the benefits of using a mycobiont to enhance in vitro germination and possibly ex vitro acclimatization and sustainability following outplanting. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company.

First-year survival and growth of bottomland oak species following intensive establishment procedures

Treesearch

Andrew B. Self; Andrew W. Ezell; Michael R. Guttery

2006-01-01

Oak seedlings are annually planted on thousands of acres in the South. While the majority of these seedlings are planted for timber production, there is increasing interest in oak establishment for mast production. In this study, seedlings of nine oak species were grown under a protocol developed by Dr. Paul Kormanik designed to produce an “enhanced” seedling of larger...

Plant Gas Exchange at High Wind Speeds 1

PubMed Central

Caldwell, Martyn M.

1970-01-01

High altitude Rhododendron ferrugineum L. and Pinus cembra L. seedlings were exposed to winds at 15 meters per second for 24-hour periods. Wind-sensitive stomata of Rhododendron seedlings immediately initiated a closing response which resulted in decreased photosynthesis and an even greater reduction in transpiration. Stomatal aperture and transpiration rates of P. cembra were only slightly reduced by high speed winds. However, photosynthesis was substantially reduced because of changes in needle display to available irradiation. PMID:16657501

Cavity size and copper root pruning affect production and establishment of container-grown longleaf pine seedlings

Treesearch

Marry Anne Sword Sayer; James D. Haywood; Shi-Jean Susana Sung

2009-01-01

With six container types, we tested the effects of cavity size (i.e., 60, 93, and 170 ml) and copper root pruning on the root system development of longleaf pine (Pinus palustris Mill.) seedlings grown in a greenhouse. We then evaluated root egress during a root growth potential test and assessed seedling morphology and root system development 1 year after planting in...

Effects of untreated and treated oilfield-produced water on seed germination, seedling development, and biomass production of sunflower (Helianthus annuus L.).

PubMed

da Costa Marques, Mônica Regina; de Souza, Paulo Sérgio Alves; Rigo, Michelle Machado; Cerqueira, Alexandre Andrade; de Paiva, Julieta L; Merçon, Fábio; Perez, Daniel Vidal

2015-10-01

This study aims to evaluate possible toxic effects of oil and other contaminants from oilfield-produced water from oil exploration and production, on seed germination, and seedling development of sunflower (Helianthus annuus L.). In comparison, as treated by electroflocculation, oilfield-produced water, with lower oil and organic matter content, was also used. Electroflocculation treatment of oilfield-produced water achieved significant removals of chemical oxygen demand (COD) (94 %), oil and grease (O&G) (96 %), color (97 %), and turbidity (99 %). Different O&G, COD, and salt levels of untreated and treated oilfield-produced water did not influence germination process and seedling biomass production. Normal seedlings percentage and vigor tended to decrease more intensely in O&G and COD levels, higher than 337.5 mg L(-1) and 1321 mg O2 L(-1), respectively, using untreated oilfield-produced water. These results indicate that this industrial effluent must be treated, in order to not affect adversely seedling development. This way, electroflocculation treatment appears as an interesting alternative to removing oil and soluble organic matter in excess from oilfield-produced water improving sunflower's seedling development and providing a friendly environmental destination for this wastewater, reducing its potential to harm water resources, soil, and biota.

Phloem transport velocity varies over time and among vascular bundles during early cucumber seedling development.

PubMed

Savage, Jessica A; Zwieniecki, Maciej A; Holbrook, N Michele

2013-11-01

We use a novel dye-tracing technique to measure in vivo phloem transport velocity in cucumber (Cucumis sativus) plants during early seedling development. We focus on seedlings because of their importance in plant establishment and because they provide a simple source and sink model of phloem transport. The dye-tracing method uses a photodiode to track the movement of a bleach front of fluorescent dye traveling in the phloem from the cotyledons (source) to the roots (sink). During early seedling development, phloem transport velocity in this direction can change 2-fold depending on vascular connectivity and the number of actively growing sinks. Prior to leaf expansion, vascular bundles attached to the first developing leaf demonstrate a decline in basipetal phloem transport that can be alleviated by the leaf's removal. At this stage, seedlings appear carbon limited and phloem transport velocity is correlated with cotyledon area, a pattern that is apparent both during cotyledon expansion and after source area manipulation. When the first leaf transitions to a carbon source, seedling growth rate increases and basipetal phloem transport velocity becomes more stable. Because bundles appear to operate autonomously, transport velocity can differ among vascular bundles. Together, these results demonstrate the dynamic and heterogeneous nature of phloem transport and underline the need for a better understanding of how changes in phloem physiology impact growth and allocation at this critical stage of development.

[Response and adaptation of photosynthesis of cucumber seedlings to high temperature stress].

PubMed

Sun, Sheng Nan; Wang, Qiang; Sun, Chen Chen; Liu, Feng Jiao; Bi, Huan Gai; Ai, Xi Zhen

2017-05-18

Cucumber seedlings (Cucumis sativus Jinyou 35) were used to study the effects of high temperature (HT: 42 ℃/32 ℃) and sub-high temperature (SHT: 35 ℃/25 ℃) on its photosynthesis and growth. The results showed that the growth of cucumber seedlings was dramatically inhibited by the high and sub-high temperature stresses. The photosynthetic rate (P n ) was gradually reduced, while intercellular CO 2 concentration (C i ) was increased as heat stress lasted. Under heat stress, stomatal conductance (g s ), transpiration rate (T r ), photorespiration rate (P r ) and dark respiration rate (D r ) showed a trend from rise to decline in cucumber seedlings, which implied that heat-induced decline of photosynthesis was mainly due to non-stomatal limitation. Maximal photochemical efficiency of PS2 in darkness (F v /F m ), actual photochemical efficiency (χ PS 2 ), photochemical quenching (q P ) and electron transport rate (ETR) were severely hampered, while initial fluorescence (F o ) and non-chemical quenching (NPQ) were increased as a result of high and sub-high temperature stresses. Under extended high temperature stress, the activities of RuBP carboxylase (RuBPCase) and Rubisco activase (RCA) as well as the mRNA abundance of Rubisco and RCA were in the trend of decrease, while they were reduced 3 days following the sub-high temperature treatment. The activities and mRNA expressions of sedoheptulose-1,7-bisphosphatase (SBPase) and fructose 1,6-bisphosphate aldolase (FBA) increased initially, but decreased afterwards under heat stress. Taken together, our data suggested that short-term sub-high temperature did not cause photoinhibition under optimal light conditions, however, high temperature led to severe damage to PS2 reaction center in cucumber seedlings. The photosynthetic enzymes were induced by high temperature stress and the induction was affected by temperature and stress duration.

Protocol for Large-Scale Collection, Processing, and Storage of Seeds of Two Mesohaline Submerged Aquatic Plant Species

DTIC Science & Technology

2006-08-01

and the regulation of the timing of initial seedling growth. The evolution of flowering plants extended the potential for regu- lating growth and...improved the efficiency of gamete transfer via pollination (Willis and Figure 1. A one-gram plant sample of R. maritima seeds Report Documentation...uniformity of plant growth and development is contrary to the goals of ecological restoration where the objective is the successful establishment of

β-Amino-n-butyric Acid Regulates Seedling Growth and Disease Resistance of Kimchi Cabbage

PubMed Central

Kim, Yeong Chae; Kim, Yeon Hwa; Lee, Young Hee; Lee, Sang Woo; Chae, Yun-Soek; Kang, Hyun-Kyung; Yun, Byung-Wook; Hong, Jeum Kyu

2013-01-01

Non-protein amino acid, β-amino-n-butyric acid (BABA), has been involved in diverse physiological processes including seedling growth, stress tolerance and disease resistance of many plant species. In the current study, treatment of kimchi cabbage seedlings with BABA significantly reduced primary root elongation and cotyledon development in a dose-dependent manner, which adverse effects were similar to the plant response to exogenous abscisic acid (ABA) application. BABA was synergistically contributing ABA-induced growth arrest during the early seedling development. Kimchi cabbage leaves were highly damaged and seedling growth was delayed by foliar spraying with high concentrations of BABA (10 to 20 mM). BABA played roles differentially in in vitro fungal conidial germination, mycelial growth and conidation of necrotroph Alternaria brassicicola causing black spot disease and hemibiotroph Colletotrichum higginsianum causing anthracnose. Pretreatment with BABA conferred induced resistance of the kimchi cabbage against challenges by the two different classes of fungal pathogens in a dose-dependent manner. These results suggest that BABA is involved in plant development, fungal development as well as induced fungal disease resistance of kimchi cabbage plant. PMID:25288957

Gibberellin is required for the formation of tension wood and stem gravitropism in Acacia mangium seedlings

PubMed Central

Nugroho, Widyanto Dwi; Yamagishi, Yusuke; Nakaba, Satoshi; Fukuhara, Shiori; Begum, Shahanara; Marsoem, Sri Nugroho; Ko, Jae-Heung; Jin, Hyun-O; Funada, Ryo

2012-01-01

Background and Aims Angiosperm trees generally form tension wood on the upper sides of leaning stems. The formation of tension wood is an important response to gravitational stimulus. Gibberellin appears to be involved in the differentiation of secondary xylem, but it remains unclear whether gibberellin plays a key role in the formation of tension wood and plant gravitropism. Therefore, a study was designed to investigate the effects of gibberellin and of inhibitors of the synthesis of gibberellin, namely paclobutrazole and uniconazole-P, on the formation of tension wood and negative stem gravitropism in Acacia mangium seedlings. Methods Gibberellic acid (GA3), paclobutrazole and uniconazole-P were applied to seedlings via the soil in which they were growing. Distilled water was applied similarly as a control. Three days after such treatment, seedlings were tilted at an angle of 45° from the vertical, and samples of stems were collected for analysis 2 weeks, 2 months and 6 months after tilting. The effects of treatments on the stem recovery degree (Rº) were analysed as an index of the negative gravitropism of seedlings, together the width of the region of tension wood in the upper part of inclined stems. Key Results It was found that GA3 stimulated the negative gravitropism of tilted seedling stems of A. mangium, while paclobutrazole and uniconazole-P inhibited recovery to vertical growth. Moreover, GA3 stimulated the formation of tension wood in tilted A. mangium seedlings, while paclobutrazole and uniconazole-P strongly suppressed the formation of tension wood, as assessed 2 weeks after tilting. Conclusions The results suggest that gibberellin plays an important role at the initial stages of formation of tension wood and in stem gravitropism in A. mangium seedlings in response to a gravitational stimulus. PMID:22843341

Gibberellin is required for the formation of tension wood and stem gravitropism in Acacia mangium seedlings.

PubMed

Nugroho, Widyanto Dwi; Yamagishi, Yusuke; Nakaba, Satoshi; Fukuhara, Shiori; Begum, Shahanara; Marsoem, Sri Nugroho; Ko, Jae-Heung; Jin, Hyun-O; Funada, Ryo

2012-09-01

Angiosperm trees generally form tension wood on the upper sides of leaning stems. The formation of tension wood is an important response to gravitational stimulus. Gibberellin appears to be involved in the differentiation of secondary xylem, but it remains unclear whether gibberellin plays a key role in the formation of tension wood and plant gravitropism. Therefore, a study was designed to investigate the effects of gibberellin and of inhibitors of the synthesis of gibberellin, namely paclobutrazole and uniconazole-P, on the formation of tension wood and negative stem gravitropism in Acacia mangium seedlings. Gibberellic acid (GA(3)), paclobutrazole and uniconazole-P were applied to seedlings via the soil in which they were growing. Distilled water was applied similarly as a control. Three days after such treatment, seedlings were tilted at an angle of 45° from the vertical, and samples of stems were collected for analysis 2 weeks, 2 months and 6 months after tilting. The effects of treatments on the stem recovery degree (Rº) were analysed as an index of the negative gravitropism of seedlings, together the width of the region of tension wood in the upper part of inclined stems. It was found that GA(3) stimulated the negative gravitropism of tilted seedling stems of A. mangium, while paclobutrazole and uniconazole-P inhibited recovery to vertical growth. Moreover, GA(3) stimulated the formation of tension wood in tilted A. mangium seedlings, while paclobutrazole and uniconazole-P strongly suppressed the formation of tension wood, as assessed 2 weeks after tilting. The results suggest that gibberellin plays an important role at the initial stages of formation of tension wood and in stem gravitropism in A. mangium seedlings in response to a gravitational stimulus.

Colonization of citrus seed coats by 'Candidatus Liberibacter asiaticus': implications for seed transmission of the bacterium.

PubMed

Hilf, Mark E

2011-10-01

Huanglongbing is an economically damaging disease of citrus associated with infection by 'Candidatus Liberibacter asiaticus'. Transmission of the organism via infection of seeds has not been demonstrated but is a concern since some citrus varieties, particularly those used as rootstocks in commercial plantings are propagated from seed. We compared the incidence of detection of 'Ca. Liberibacter asiaticus' DNA in individual fruit peduncles, seed coats, seeds, and in germinated seedlings from 'Sanguenelli' sweet orange and 'Conners' grapefruit fruits sampled from infected trees. Using real-time quantitative PCR (qPCR) we detected pathogen DNA in nucleic acid extracts of 36 and 100% of peduncles from 'Sanguenelli' and from 'Conners' fruits, respectively. We also detected pathogen DNA in extracts of 37 and 98% of seed coats and in 1.6 and 4% of extracts from the corresponding seeds of 'Sanguenelli' and 'Conners', respectively. Small amounts of pathogen DNA were detected in 10% of 'Sanguenelli' seedlings grown in the greenhouse, but in none of 204 extracts from 'Conners' seedlings. Pathogen DNA was detected in 4.9% and in 89% of seed coats peeled from seeds of 'Sanguenelli' and 'Conners' which were germinated on agar, and in 5% of 'Sanguenelli' but in none of 164 'Conners' seedlings which grew from these seeds on agar. No pathogen DNA was detected in 'Ridge Pineapple' tissue at 3 months post-grafting onto 'Sanguenelli' seedlings, even when pathogen DNA had been detected initially in the 'Sanguenelli' seedling. Though the apparent colonization of 'Conners' seeds was more extensive and nearly uniform compared with 'Sanguenelli' seeds, no pathogen DNA was detected in 'Conners' seedlings grown from these seeds. For either variety, no association was established between the presence of pathogen DNA in fruit peduncles and seed coats and in seedlings.

Dying piece by piece: carbohydrate dynamics in aspen (Populus tremuloides) seedlings under severe carbon stress.

PubMed

Wiley, Erin; Hoch, Günter; Landhäusser, Simon M

2017-11-02

Carbon starvation as a mechanism of tree mortality is poorly understood. We exposed seedlings of aspen (Populus tremuloides) to complete darkness at 20 or 28 °C to identify minimum non-structural carbohydrate (NSC) concentrations at which trees die and to see if these levels vary between organs or with environmental conditions. We also first grew seedlings under different shade levels to determine if size affects survival time under darkness due to changes in initial NSC concentration and pool size and/or respiration rates. Darkness treatments caused a gradual dieback of tissues. Even after half the stem had died, substantial starch reserves were still present in the roots (1.3-3% dry weight), indicating limitations to carbohydrate remobilization and/or transport during starvation in the absence of water stress. Survival time decreased with increased temperature and with increasing initial shade level, which was associated with smaller biomass, higher respiration rates, and initially smaller NSC pool size. Dead tissues generally contained no starch, but sugar concentrations were substantially above zero and differed between organs (~2% in stems up to ~7.5% in leaves) and, at times, between temperature treatments and initial, pre-darkness shade treatments. Minimum root NSC concentrations were difficult to determine because dead roots quickly began to decompose, but we identify 5-6% sugar as a potential threshold for living roots. This variability may complicate efforts to identify critical NSC thresholds below which trees starve. © Society for Experimental Biology 2017.

Multi-Stage Metering Mechanism for Transplanting of Vegetable Seedlings in Paper Pots

NASA Astrophysics Data System (ADS)

Nandede, B. M.; Raheman, H.

2015-12-01

A multi-stage rotating cup type metering mechanism was developed for transplanting of vegetable seedlings of tomato, brinjal and chili raised in paper pots. The developed setup consisted of a seedling feeding wheel, metering wheel, fixed slotted plate, seedling delivery tube, furrow opener, furrow closer and a power transmission system. Its evaluation was carried out with pot seedlings of tomato, brinjal and chili of 8-11 cm height at five forward speeds (0.6, 0.9, 1.2, 2.2 and 3.2 km/h) and two plant spacings (45 and 60 cm) in controlled soil bin condition. The mean values of feeding efficiency, conveying efficiency, planting efficiency and overall efficiency of the multistage metering unit were observed to be higher than 90 % for forward speeds of 0.6 to 2.2 km/h. With further increase in speed to 3.2 km/h, the feeding and conveying efficiency were observed to be higher than 90 %, whereas, the planting efficiency drastically reduced to around 50 % due to the problem in getting the pot seedlings vertically in the furrow. Also the seedlings were falling into the furrow at an angle greater than 70° to the vertical, hence not suitable for transplanting.

Potential effects of arboreal and terrestrial avian dispersers on seed dormancy, seed germination and seedling establishment in Ormosia (Papilionoideae) species in Peru

USGS Publications Warehouse

Foster, Mercedes S.

2008-01-01

The relative effectiveness of arboreal or terrestrial birds at dispersing seeds of Ormosia macrocalyx and O. bopiensis (Fabaceae: Papilionoideae) were studied in south-eastern Peru. Seeds of both species were either scarified, to represent seed condition after dispersal by terrestrial birds, or left intact, to represent seed condition after dispersal by arboreal birds. Seeds were distributed along forest transects, and germination, seedling development and mortality were monitored to determine the successes of the two groups at producing seedlings. Scarified seeds germinated with the early rains of the dry-to-wet-season transition, when erratic rainfall was interspersed with long dry spells. Intact seeds germinated 30 d later when the rain was more plentiful and regular. Intact seeds of O. macrocalyx gave rise to significantly more seedlings (41.1% vs. 25.5%) than did scarified seeds, in part, because significantly more seedlings from scarified seeds (n = 20) than from intact seeds (n = 3) died from desiccation when their radicles failed to enter the dry ground present during the dry-to-wet-season transition. Also, seedlings from scarified seeds were neither larger nor more robust than those from intact seeds despite their longer growing period. Results are consistent with the hypothesis that dispersal effectiveness of arboreal birds, at least for O. macrocalyx, is greater than that of terrestrial birds. Screen-house experiments in which seedlings developed under different watering regimes supported this result. Numbers of seedlings developing from intact and scarified seeds of O. bopiensis did not differ significantly.

Growth models of Rhizophora mangle L. seedlings in tropical southwestern Atlantic

NASA Astrophysics Data System (ADS)

Lima, Karen Otoni de Oliveira; Tognella, Mônica Maria Pereira; Cunha, Simone Rabelo; Andrade, Humber Agrelli de

2018-07-01

The present study selected and compared regression models that best describe the growth curves of Rhizophora mangle seedlings based on the height (cm) and time (days) variables. The Linear, Exponential, Power Law, Monomolecular, Logistic, and Gompertz models were adjusted with non-linear formulations and minimization of the sum of the squares of the residues. The Akaike Information Criterion was used to select the best model for each seedling. After this selection, the determination coefficient, which evaluates how well a model describes height variation as a time function, was inspected. Differing from the classic population ecology studies, the Monomolecular, Three-parameter Logistic, and Gompertz models presented the best performance in describing growth, suggesting they are the most adequate options for long-term studies. The different growth curves reflect the complexity of stem growth at the seedling stage for R. mangle. The analysis of the joint distribution of the parameters initial height, growth rate, and, asymptotic size allowed the study of the species ecological attributes and to observe its intraspecific variability in each model. Our results provide a basis for interpretation of the dynamics of seedlings growth during their establishment in a mature forest, as well as its regeneration processes.

Effects of Salinity and Nutrient Addition on Mangrove Excoecaria agallocha

PubMed Central

Chen, Yaping; Ye, Yong

2014-01-01

Effects of salinity on seed germination and growth of young (1 month old) and old (2-year old) seedlings of Excoecaria agallocha were investigated. Combined effects of salinity and nutrient level were also examined on old seedlings. Seed germination was best at 0 and 5 psu salinity. 15 psu salinity significantly delayed root initiation and decreased final establishment rate. All seeds failed to establish at 25 psu salinity. Young seedlings performed best at 0 and 5 psu, but growth was stunned at 15 psu, and all seedlings died within 90 days at 25 psu. Old seedlings grew best at salinities below 5 psu and they survived the whole cultivation at 25 psu. This indicated that E. agallocha increased salt tolerance over time. Gas exchange was significantly compromised by salinities above 15 psu but evidently promoted by high nutrient. Proline accumulated considerably at high nutrient, and its contents increased from 0 to 15 psu but decreased at 25 psu salinity. Lipid peroxidation was aggravated by increasing salinity beyond 15 psu but markedly alleviated by nutrient addition. These responses indicated that E. agallocha was intolerant to high salinity but it can be greatly enhanced by nutrient addition. PMID:24691495

Screening of bacterial antagonists for biological control of Phytophthora blight of pepper.

PubMed

Rajkumar, M; Lee, Wang Hyu; Lee, Kui Jae

2005-01-01

The aim of this study was to assess the potential of bacterial antagonists to control Phytophthora blight of pepper caused by P. capsici using different screening methods. Among a collection of fluorescent pseudomonas isolated from the rhizosphere of pepper, twelve isolates were initially selected based on dual culture assay on potato dextrose agar and corn meal agar. Further, these twelve isolates were screened for the reduction of disease severity caused by P. capsici using detached leaves and seedling assay. Most of the antagonists showed varying levels of antagonism against P. capsici in both detached leaves and seedlings assay. In addition, few isolates increased shoot and root length of pepper in seedling assays. Among them, isolate PS119 showing highest ability to reduce the disease severity in the in vitro seedling assay was found to be the most efficient antagonists against P. capsici in the in vivo biological control tests. These results indicate that the in vitro seedling assay can be used as a rapid and more accurate technique for the selection of promising biocontrol agents against P. capsici. ((c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

Interactive effects of cadmium and acid rain on photosynthetic light reaction in soybean seedlings.

PubMed

Sun, Zhaoguo; Wang, Lihong; Chen, Minmin; Wang, Lei; Liang, Chanjuan; Zhou, Qing; Huang, Xiaohua

2012-05-01

Interactive effects of cadmium (Cd(2+)) and acid rain on photosynthetic light reaction in soybean seedlings were investigated under hydroponic conditions. Single treatment with Cd(2+) or acid rain and the combined treatment decreased the content of chlorophyll, Hill reaction rate, the activity of Mg(2+)-ATPase, maximal photochemical efficiency and maximal quantum yield, increased initial fluorescence and damaged the chloroplast structure in soybean seedlings. In the combined treatment, the change in the photosynthetic parameters and the damage of chloroplast structure were stronger than those of any single pollution. Meanwhile, Cd(2+) and acid rain had the interactive effects on the test indices in soybean seedlings. The results indicated that the combined pollution of Cd(2+) and acid rain aggravated the toxic effect of the single pollution of Cd(2+) or acid rain on the photosynthetic parameters due to the serious damage to the chloroplast structure. Copyright © 2011 Elsevier Inc. All rights reserved.

Ontogeny of the Maize Shoot Apical Meristem[W][OA

PubMed Central

Takacs, Elizabeth M.; Li, Jie; Du, Chuanlong; Ponnala, Lalit; Janick-Buckner, Diane; Yu, Jianming; Muehlbauer, Gary J.; Schnable, Patrick S.; Timmermans, Marja C.P.; Sun, Qi; Nettleton, Dan; Scanlon, Michael J.

2012-01-01

The maize (Zea mays) shoot apical meristem (SAM) arises early in embryogenesis and functions during stem cell maintenance and organogenesis to generate all the aboveground organs of the plant. Despite its integral role in maize shoot development, little is known about the molecular mechanisms of SAM initiation. Laser microdissection of apical domains from developing maize embryos and seedlings was combined with RNA sequencing for transcriptomic analyses of SAM ontogeny. Molecular markers of key events during maize embryogenesis are described, and comprehensive transcriptional data from six stages in maize shoot development are generated. Transcriptomic profiling before and after SAM initiation indicates that organogenesis precedes stem cell maintenance in maize; analyses of the first three lateral organs elaborated from maize embryos provides insight into their homology and to the identity of the single maize cotyledon. Compared with the newly initiated SAM, the mature SAM is enriched for transcripts that function in transcriptional regulation, hormonal signaling, and transport. Comparisons of shoot meristems initiating juvenile leaves, adult leaves, and husk leaves illustrate differences in phase-specific (juvenile versus adult) and meristem-specific (SAM versus lateral meristem) transcript accumulation during maize shoot development. This study provides insight into the molecular genetics of SAM initiation and function in maize. PMID:22911570

Fusarium spp. and Pinus strobus seedlings: root disease pathogens and taxa associated with seed

Treesearch

C. M. Ocamb; J. Juzwik; F. B. Martin

2002-01-01

Eastern white pine (Pinus strobus L .) seeds were sown in soil infested wlth Fusarium proliferatum, root necrosis developed on seedling roots, and F. proliferatum as reisolated from symptomatic roots; thus, demonstrating that F. proliferatum is pathogenic to eastern white pine seedling. Soils...

Mycorrhizas on nursery and field seedlings of Quercus garryana

Treesearch

Dariene Southworth; Elizabeth M. Carrington; Jonathan L. Frank; Peter Gould; Connie A. Harrington; Warren D. Devine

2009-01-01

Oak woodland regeneration and restoration requires that seedlings develop mycorrhizas, yet the need for this mutualistic association is often overlooked. In this study, we asked whether Quercus garryana seedlings in nursery beds acquire mycorrhizas without artificial inoculation or access to a mycorrhizal network of other ectomycorrhizal hosts. We...

2008 interim guidelines for growing longleaf pine seedlings in container nurseries

Treesearch

R. Kasten Dumroese; James P. Barnett; D. Paul Jackson; Mark J. Hainds

2013-01-01

Production of container longleaf pine (Pinus palustris Mill.) seedlings for reforestation and restoration exceeds that of bare-root production, but information on container production techniques has been slow to develop. Because outplanting success requires quality seedlings, interim guidelines were proposed in 2002 to assist nursery managers and...

2008 interim guidelines for growing longleaf pine seedlings in container nurseries

Treesearch

R. Kasten Dumroese; James P. Barnett; D. Paul Jackson; Mark J. Hainds

2009-01-01

Production of container longleaf pine (Pinus palustris) seedlings for reforestation and restoration plantings exceeds that of bareroot production, but information on container production techniques has been slow to develop. Because success of those outplantings requires quality seedlings, interim guidelines were proposed in 2002 to assist nursery...

Use of a beneficial strain of Trichoderma to protect Pinus sylvestris seedlings

Treesearch

T. V. Ryazanova; V. S. Gromoykh; S. V. Prudnicova; V. A. Tulpanova

2002-01-01

In forest nursery practice, the mechanism of phytopathogen suppression by soil saprophytes is used to protect seedlings against root rot. An important stage is the formation and maintenance of a microbial association which will provide extended inhibition of phytopathogen development and growth of healthy seedlings.

Valley Oak Seedling Growth Associated with Selected Grass Species

Treesearch

Karen C. Danielsen; William L. Halvorson

1991-01-01

Valley oak (Quercus lobata Née) has exhibited inadequate regeneration since the last century. Seedlings become established, but few develop into saplings. We hypothesized that the invasion of alien annual grasses into native perennial grasslands has increased oak seedling mortality by decreasing soil moisture availability. We conducted greenhouse...

Auxin efflux facilitator and auxin dynamism responsible for the gravity-regulated development of peg in cucumber seedlings

NASA Astrophysics Data System (ADS)

Takahashi, Hideyuki; Watanabe, Chiaki; Fujii, Nobuharu; Miyazawa, Yutaka

Cucumber seedlings develop a protuberance, peg, by which seed coats are pulled out just af-ter germination. The peg is usually formed on the lower side of the transition zone between hypocotyl and root of the seedlings grown in a horizontal position. Our previous spaceflight experiment showed that unilateral positioning of a peg in cucumber seedlings occurred due to its suppression on the upper side of the transition zone because seedlings grown in microgravity developed a peg on each side of the transition zone. We also showed that auxin was a major factor responsible for peg development. There was a redistribution of auxin in the gravistimu-lated transition zone, decreasing IAA level on the upper side, and IAA application induced a peg on both lower and upper sides of the transition zone. In addition, peg was released from its suppression in the seedlings treated with inhibitors of auxin efflux. Namely, two pegs devel-oped in the TIBA-treated seedlings even when they were grown in a horizontal position. These results imply that a reduction of auxin level due to its efflux is required for the suppression of peg development on the upper side of the transition zone in a horizontal position. To under-stand molecular mechanism underlying the negative control of morphogenesis by graviresponse in cucumber seedlings, we isolated cDNAs of auxin efflux facilitators, CsPINs, from cucumber and examined the expressions of their proteins, in relation to the redistribution of endogenous auxin and peg development. We isolated six cDNAs of PIN homologues CsPIN1 to CsPIN6 from cucumber. By immunohistochemical study using some of their anti-bodies, we revealed that CsPIN1 was localized in endodermis, vascular tissue and pith around the transition zone of cucumber seedlings. In cucumber seedlings grown in a vertical position with radicles pointing down, CsPIN1 in endodermal cells was mainly localized on the plasma membrane neighboring vascular bundle but not on the plasma membrane next to the cortex. This CsPIN1 localization could play a role in transporting auxin from cortex to vascular bundle. In both vascular and pith tissues, CsPIN1 was localized on the bottom plasma membrane of the cells, which could allow auxin to move toward the roots. In the seedlings grown in a horizontal position, endoder-mal cells situated above the vascular bundle localized CsPIN1 on the lower plasma membrane, whereas the polarized localization of CsPIN1 in endodermal cells situated below the vascular bundle became less clear. This differential expression of CsPIN1 in the endodermis commenced within 30 min after gravistimulation. We measured endogenous IAA contents in the transi-tion zone of the 24-hour-old seedlings. In the longitudinally halved transition zone of seedlings grown in a horizontal position, free IAA content was significantly lowered in the upper side, compared to that of the lower side or either side of the transition zone in a vertical position. When 24-hour-old seedlings grown in a vertical position were gravistimulated by reorienting them to the horizontal, free IAA in the lower side of the transition zone increased by 30 min after gravistimulation and eventually decreased to the control level by 180 min after gravistim-ulation. IAA content in the upper side of the transition zone did not change much and was comparable to that in the vertical transition zone during 180 min after gravistimulation. Thus, it appears that gravistimulation causes an immediate increase of IAA level in the lower side and its eventual decrease in the upper side of the transition zone. The gravity-induced changes in CsPIN1 localization in endodermal cells could be involved in auxin redistribution that leads to unilateral positioning of a peg in cucumber seedlings.

The Dehydratase ADT3 Affects ROS Homeostasis and Cotyledon Development1[OPEN

PubMed Central

Para, Alessia; Muhammad, DurreShahwar; Naldrett, Michael J.; Warpeha, Katherine M.

2016-01-01

During the transition from seed to seedling, emerging embryos strategically balance available resources between building up defenses against environmental threats and initiating the developmental program that promotes the switch to autotrophy. We present evidence of a critical role for the phenylalanine (Phe) biosynthetic activity of AROGENATE DEHYDRATASE3 (ADT3) in coordinating reactive oxygen species (ROS) homeostasis and cotyledon development in etiolated Arabidopsis (Arabidopsis thaliana) seedlings. We show that ADT3 is expressed in the cotyledon and shoot apical meristem, mainly in the cytosol, and that the epidermis of adt3 cotyledons contains higher levels of ROS. Genome-wide proteomics of the adt3 mutant revealed a general down-regulation of plastidic proteins and ROS-scavenging enzymes, corroborating the hypothesis that the ADT3 supply of Phe is required to control ROS concentration and distribution to protect cellular components. In addition, loss of ADT3 disrupts cotyledon epidermal patterning by affecting the number and expansion of pavement cells and stomata cell fate specification; we also observed severe alterations in mesophyll cells, which lack oil bodies and normal plastids. Interestingly, up-regulation of the pathway leading to cuticle production is accompanied by an abnormal cuticle structure and/or deposition in the adt3 mutant. Such impairment results in an increase in cell permeability and provides a link to understand the cell defects in the adt3 cotyledon epidermis. We suggest an additional role of Phe in supplying nutrients to the young seedling. PMID:27540109

Early seedling vigour, an imperative trait for direct-seeded rice: an overview on physio-morphological parameters and molecular markers.

PubMed

Mahender, A; Anandan, A; Pradhan, S K

2015-05-01

Rapid uniform germination and accumulation of biomass during initial phase of seedling establishment is an essential phenotypic trait considered as early seedling vigour for direct seeded situation in rice irrespective of environment. Enhanced role of carbohydrate, amylase, growth hormones, antioxidant enzymes and ascorbic acid brings changes in vigour and phenotype of seedling. Early establishment and demanding life form dominate the surroundings. Crop plant that has better growth overdrives the weed plant and suppresses its growth. Seedling early vigour is the characteristic of seed quality and describes the rapid, uniform germination and the establishment of strong seedlings in any environmental condition. The phenotype of modern rice varieties has been changed into adaptable for transplanted rice with thirst toward water and selection pressure for semi-dwarf architecture resulting in reduced early vigour. Decreasing freshwater availability and rising labour cost drives the search for a suitable alternative management system to enhance grain yield productivity for the burgeoning world population. In view of these issues, much attention has been focused on dry direct-seeded rice, because it demands low input. A rice cultivar with a strong seedling vigour trait is desirable in case of direct seeding. However, seedling vigour has not been selected in crop improvement programmes in conventional breeding due to its complex nature and quantitative inheritance. Molecular markers have been proven effective in increasing selection efficiency, particularly for quantitative traits that are simply inherited. Marker-assisted selection approach has facilitated efficient and precise transfer of genes/QTL(s) into many crop species and suggests a speedy and efficient technique over conventional breeding and selection methods. In this review, we present the findings and investigations in the field of seedling vigour in rice that includes the nature of inheritance of physio-morphological and biochemical traits and QTLs to assist plant breeders who work for direct-seeded rice.

The role of habitat factors in successful invasion of alien plant Acer negundo in riparian zones.

NASA Astrophysics Data System (ADS)

Sikorski, Piotr; Sikorska, Daria

2016-04-01

Ash-leaved maple (Acer negundo) is one of the most invasive species occurring in riparian zones. The invasion is especially effective in disturbed areas, as the plant favours anthropogenic sites. The plant was also observed to be able to penetrate into sandy bars, also those separated from the land, inaccessible to people. It's removal is time-consuming and laborious, often involves damage done to sensitive vegetation and the results are doubtful, as the plant quickly regenerates. The invasion patterns and establishment of ash-leaved maple in natural ecosystems are poorly investigated. The aim of this study was to test how habitat factors such as: light availability, soil characteristics and competition contribute to ash-leaved maple effective colonization of natural sand bars free from anthropogenic pressure. In 2014 sand bars located in Vistula River Valley in Warsaw were inventoried and classified basing on their development stage as 1 - initial, 2 - unstable, 3 - stable. Apart from the occurrence of the invasive ash-leaved maple the plants competing with it were recognized and the percentage of the shoots of shrubs and herbaceous plants was estimated. PAR was measured at ground level and 1 meter above ground, the thickness of organic layer formed on the top of the sand was also measured as the indicator of sand bar development stage. The maple's survival in extremely difficult conditions resembles the strategy of willows and poplars naturally occurring in the riparian zones, which are well adapted to this environment. The success of invasion strongly depends on the plants establishment during sand bars initial stage of development. The seedlings growth correlates with the age of the sand bar (r1=0,41, r2=0,42 i r3=0,57). The colonization lasts for 4-6 years and the individuals start to cluster in bigger parches. After that period the maple turns into the phase of competition for space. Habitat factors such as shading (r2=0,41 i r3=0,51) and organic layer thickness (r2=0,35 i r3=0,35) become limiting factors to the plants development. The diversity of shoot age increases with the bars age (r=0,78), but the new emerging shoots are suckers rather than newly established seedlings. The removal of ash-leaved maple in the early development stage is ineffective as this is a period when high number of seedlings develop. The removal at the later stage leads to damage done to sensitive herbaceous vegetation which is developed by then. Management of the invasive ash-leaved maple should be held on sand bars older than 10 years, the moment the competition of other trees and shrubs reduces the establishment of new seedlings. Removal of trees of diameter bigger than 10 cm will impair the plants expansion with minimal damage done to the habitat.

In planta transformation of pigeon pea: a method to overcome recalcitrancy of the crop to regeneration in vitro.

PubMed

Sankara Rao, K; Sreevathsa, Rohini; Sharma, Pinakee D; Keshamma, E; Udaya Kumar, M

2008-10-01

Development of transgenics in pigeon pea remains dogged by poor plant regeneration in vitro from transformed tissues and low frequency transformation protocols. This article presents a non-tissue culture-based method of generating transgenic pigeon pea (Cajanus cajan (L.) Millisp.) plants using Agrobacterium-Ti plasmid-mediated transformation system. The protocol involves raising of whole plant transformants (T0 plants) directly from Agrobacterium-infected young seedlings. The plumular and intercotyledonary meristems of the seedling axes are targeted for transformation. The transformation conditions optimized were, pricking of the apical and intercotyledonary region of the seedling axes of two-day old germinating seedlings with a sewing needle, infection with Agrobacterium (LBA4404/pKIWI105 carrying uid A and npt II genes) in Winans' AB medium that was added with wounded tobacco leaf extract, co-cultivation in the same medium for 1h and transfer of seedlings to soilrite for further growth and hardening and subsequent transfer of seedlings to soil in pots in the greenhouse. Out of the 22-25 primary transformants that survived infection-hardening treatments from each of the three experiments, 15 plants on the average established on the soil under greenhouse conditions, showed slow growth initially, nevertheless grew as normal plants, and flowered and set seed eventually. Of the several seeds harvested from all the T0 plants, six hundred were sown to obtain progeny (T1) plants and 350 of these were randomly analysed to determine their transgenic nature. PCR was performed for both gus (uid A) and npt II genes. Forty eight of the 350 T1 plants amplified both transgenes. Southern blot analysis substantiated the integration and transmission of these genes. The protocol ensured generation of pigeon pea transgenic plants with considerable ease in a short time and is applicable across different genotypes/cultivars of the crop and offers immense potential as a supplemental or an alternative protocol for generating transgenic plants of difficult-to-regenerate pigeon pea. Further, the protocol offers the option of doing away with a selection step in the procedure and so facilitates transformation, which is free of marker genes.

Avicennia schaueriana (Acanthaceae) from Southern Brazil.

PubMed

Pelozo, Andressa; Boeger, Maria Regina T; Sereneski-de-Lima, Carolina; Soffiatti, Patricia

2016-03-01

The initial phase of a plant life cycle is a short and critical period, when individuals are more vulnerable to environmental factors. The morphological and anatomical study of seedlings and saplings leaf type enables the understanding of species strategies of fundamental importance in their establishment and survival. The objective of this study was to analyze the structure of seedlings and saplings leaf types of three mangrove species, Avicennia schaueriana, Laguncularia racemosa, Rhizophora mangle, to understand their early life adaptive strategies to the environment. A total of 30 fully expanded cotyledons (A. schaueriana and L. racemosa), 30 leaves of seedlings, and 30 leaves of saplings of each species were collected from a mangrove area in Guaratuba Bay, Paraná State, Brazil. Following standard methods, samples were prepared for morphological (leaf dry mass, density, thickness) and anatomical analysis (epidermis and sub-epidermal layers, stomata types, density of salt secretion glands, palisade and spongy parenchyma thickness). To compare leaf types among species one-way ANOVA and Principal Component Analysis were used, while Cluster Analysis evaluated differences between the species. We observed significant structural differences among species leaf types. A. schaueriana showed the thickest cotyledons, while L. racemosa presented a dorsiventral structure. Higher values of the specific leaf area were observed for seedlings leaves of A. schaueriana, cotyledons of L. racemosa and saplings leaves of A. schaueriana and R. mangle. Leaf density was similar to cotyledons and seedlings leaves in A. schaueriana and L. racemosa, while R. mangle had seedlings leaves denser than saplings. A. schaueriana and R. mangle showed hypostomatic leaves, while L. racemosa amphistomatic; besides, A. chaueriana showed diacytic stomata, while L. racemosa anomocytic, and R. mangle ciclocytic. Seedling leaves were thicker in R. mangle (535 μm) and L. racemosa (520 μm) than in A. schaueriana (470.3 μm); while saplings leaves were thicker in L. racemosa (568.3 μm) than in A. schaueriana seedlings (512.4 μm) and R. mangle (514.6 μm). Besides, seedlings leaves palisade parenchyma showed increasing thickness in L. racemosa (119.2 μm) < A. schaueriana (155.5 μm) < R. mangle (175.4 μm); while in saplings leaves as follows R. mangle (128.4 μm) < A. schaueriana (183.4 μm) < L. racemosa (193.9 μm). Similarly, seedlings leaves spongy parenchyma thickness values were as follows A. schaueriana (182.6 μm) = R. mangle (192.8 μm) < L. racemosa (354.4 μm); while in saplings were A. schaueriana (182.6 μm) = R. mangle (187.3 μm) < L. racemosa (331.3 μm). The analyzed traits, in different combinations, represent morphological adjustments of leaf types to reduce water loss, eliminate salt excess, increase the absorption of light, allowing a higher efficiency on the maintenance of physiological processes in this initial growth stage.

Why Seedlings Die: Linking Carbon and Water Limitations to Mechanisms of Mortality During Establishment in Conifer Seedlings

NASA Astrophysics Data System (ADS)

Reinhardt, K.; Germino, M. J.; Kueppers, L. M.; Mitton, J.; Castanha, C.

2012-12-01

BACKGROUND Recent ecophysiological studies aimed at explaining adult tree mortality during drought have examined the carbon (C)-exhaustion compared to the hydraulic-failure hypotheses for death. Prolonged drought leads to durations of stomatal closure (and thus limited C gain), which could result in long periods of negative C balance and fatal reductions in whole-plant C reserves (i.e., available non-structural carbohydrates ["NSC"]). Alternatively, C reserves may not decrease much but could become increasingly inaccessible to sink tissues in long dry-periods due to impediments to translocation of photosynthate (e.g., through disruption of hydrostatic pressure flow in phloem). As C reserves decline or become inaccessible, continued maintenance respiration has been hypothesized to lead to exhaustion of NSC after extended durations of drought, especially in isohydric plant species. On the other hand, hydraulic failure (e.g., catastrophic xylem embolisms) during drought may be the proximate cause of death, occurring before true C starvation occurs. Few studies have investigated specifically the mechanism(s) of tree death, and no published studies that we know of have quantified changes in NSC during mortality. EXPERIMENTAL DESIGN AND HYPOTHESES We conducted two studies that investigated whole-tree and tissue-specific C relations (photosynthetic C gain, respiration, dry-mass gain, and NSC pools) in Pinus flexilis seedlings during the initial establishment phase, which is characterized by progressive drought during summer. We measured survival, growth and biomass allocation, and C-balance physiology (photosynthetic C-gain and chlorophyll fluorescence, respiration C-use, and NSC concentrations) from germination to mortality. We hypothesized that 1) stomatal and biochemical limitations to C gain would constrain seedling survival (through inadequate seasonal C-balance), as has been shown for conifer seedlings near alpine treeline; 2) hydraulic constraints (embolisms and/or reduced hydraulic conductance), associated with roots unable to escape the seasonal drying front in the soil, would limit seedling survival at least as much as C-balance dysfunction; and 3) seedling mortality would not be due to exhaustion of whole-plant NSC, as suggested by appreciable NSC in dead conifer seedlings reported in alpine treeline studies. RESULTS AND INTERPRETATIONS Preliminary results suggest that photosynthesis, fluorescence, and whole-tree NSC remained high until mortality, when plant water potentials decreased below -5 MPa. As seedlings approached mortality, NSC concentrations (both soluble sugars and starch) in roots decreased from ~9% to <3% of dry-mass. In aboveground tissues, NSC concentrations also declined initially (from ~12% to 3% of dry-mass), but then increased in needles (up to 8% dry-mass) and especially stems (up to 16% dry-mass), suggesting impediments to phloem-translocation in stems. Thus, seedling death could not be directly attributed to dysfunction of C-balance physiology, or exhaustion of NSC at the whole-plant level. We propose that hydraulic failure was likely the proximate cause of mortality under the conditions we evaluated, and drought-induced inhibition of NSC transport to roots may ultimately undermine the ability of seedlings to tap progressively deeper water sources during summer drying.

Inter- and intrapopulation variation in the response of tree seedlings to drought: physiological adjustments based on geographical origin, water supply and species.

PubMed

Carevic, Felipe S; Delatorre-Herrera, José; Delatorre-Castillo, José

2017-09-01

Initiatives to restore natural ecosystems have had little success in arid and hyperarid ecosystems. In this context, the natural seedling establishment is particularly affected by drought patterns and climatic variability. Likewise, the effect of plant provenance on forest restoration success remains unclear, although previous studies have concluded that some seed locations might be better able to tolerate water stress. In this study, we examined the physiological mechanisms involved in the drought stress resistance of Prosopis tamarugo and Prosopis alba seedlings from different arid and hyperarid locations of the Atacama Desert in northern Chile. We measured the xylem water potential (Ψ), cuticular transpiration (E c ), specific leaf area (SLA) and pressure-volume curves at the intrapopulation and interpopulation levels of seedlings of both species subjected to three drought-induced treatments. In addition, plant characteristics such as seedling height (Sh), stem diameter (Sd), leaf biomass (Lb), root biomass (Rb) and seedling survival (Ss) were measured during the treatments. Seedlings of most hyperarid habitats had the highest values of Ψ and water content relative to the turgor loss point, as well as decreased SLA, especially during the strongest drought treatment. Ψ was strongly correlated with Sh in both species, and soil humidity was correlated with Sd. This study highlights the high variability of physiological responses to water stress in both species at the interpopulation and intrapopulation levels, which provides us with a powerful seed selection tool for future reforestation programmes aimed at the early selection and genetic improvement of species of the Prosopis genus.

Inter- and intrapopulation variation in the response of tree seedlings to drought: physiological adjustments based on geographical origin, water supply and species

PubMed Central

Delatorre-Herrera, José; Delatorre-Castillo, José

2017-01-01

Abstract Initiatives to restore natural ecosystems have had little success in arid and hyperarid ecosystems. In this context, the natural seedling establishment is particularly affected by drought patterns and climatic variability. Likewise, the effect of plant provenance on forest restoration success remains unclear, although previous studies have concluded that some seed locations might be better able to tolerate water stress. In this study, we examined the physiological mechanisms involved in the drought stress resistance of Prosopis tamarugo and Prosopis alba seedlings from different arid and hyperarid locations of the Atacama Desert in northern Chile. We measured the xylem water potential (Ψ), cuticular transpiration (Ec), specific leaf area (SLA) and pressure–volume curves at the intrapopulation and interpopulation levels of seedlings of both species subjected to three drought-induced treatments. In addition, plant characteristics such as seedling height (Sh), stem diameter (Sd), leaf biomass (Lb), root biomass (Rb) and seedling survival (Ss) were measured during the treatments. Seedlings of most hyperarid habitats had the highest values of Ψ and water content relative to the turgor loss point, as well as decreased SLA, especially during the strongest drought treatment. Ψ was strongly correlated with Sh in both species, and soil humidity was correlated with Sd. This study highlights the high variability of physiological responses to water stress in both species at the interpopulation and intrapopulation levels, which provides us with a powerful seed selection tool for future reforestation programmes aimed at the early selection and genetic improvement of species of the Prosopis genus. PMID:28948009

Plant development in the absence of epiphytic microorganisms

NASA Astrophysics Data System (ADS)

Kutschera, U.; Koopmann, V.; Grotha, R.

2002-05-01

Microorganisms (bacteria, fungi) are common residents of the roots, stems and leaves of higher plants. In order to explore the dependency of plant development on the presence of epiphytic microorganisms, the achenes (seeds) of sunflower (Helianthus annuus L.) were sterilized and germinated under aseptic conditions. The sterility of the seedlings was determined with the agar impression method. In seedlings from non-sterile seeds (control) that were likewise raised in a germ-free environment, all plant organs investigated (stem, cotyledons and primary leaves) were contaminated with bacteria. Hypocotyl elongation was not affected by epiphytic microorganisms. However, the growth rates of the cotyledons and primary leaves were higher in sterile seedlings compared with the control. The implications of this differential inhibition of organ development by epiphytic bacteria that are transmitted via the outer surface of the seed coat are discussed. We conclude that epiphytes in the above-ground phytosphere are not necessary for the development of the sunflower seedling.

Phloem Transport Velocity Varies over Time and among Vascular Bundles during Early Cucumber Seedling Development1[C][W][OPEN

PubMed Central

Savage, Jessica A.; Zwieniecki, Maciej A.; Holbrook, N. Michele

2013-01-01

We use a novel dye-tracing technique to measure in vivo phloem transport velocity in cucumber (Cucumis sativus) plants during early seedling development. We focus on seedlings because of their importance in plant establishment and because they provide a simple source and sink model of phloem transport. The dye-tracing method uses a photodiode to track the movement of a bleach front of fluorescent dye traveling in the phloem from the cotyledons (source) to the roots (sink). During early seedling development, phloem transport velocity in this direction can change 2-fold depending on vascular connectivity and the number of actively growing sinks. Prior to leaf expansion, vascular bundles attached to the first developing leaf demonstrate a decline in basipetal phloem transport that can be alleviated by the leaf’s removal. At this stage, seedlings appear carbon limited and phloem transport velocity is correlated with cotyledon area, a pattern that is apparent both during cotyledon expansion and after source area manipulation. When the first leaf transitions to a carbon source, seedling growth rate increases and basipetal phloem transport velocity becomes more stable. Because bundles appear to operate autonomously, transport velocity can differ among vascular bundles. Together, these results demonstrate the dynamic and heterogeneous nature of phloem transport and underline the need for a better understanding of how changes in phloem physiology impact growth and allocation at this critical stage of development. PMID:24072581

Red Pine Seedling Establishment after Shelterwood-Strip Harvesting

Treesearch

John W. Benzie; Alvin A. Alm

1977-01-01

Shelterwood-strip harvesting in a mature red pine stand provided favorable growing conditions for red pine seedlings established by planting nursery stock, by planting 10-week-old to 1-year-old tubelings, and by direct seeding. How long the shelterwood-strips can be left standing before they seriously affect seedling development to be determined

Differential effects of two phospholipase D inhibitors, 1-butanol and N-acylethanolamine, on in vivo cytoskeletal organization and Arabidopsis seedling growth.

PubMed

Motes, Christy M; Pechter, Priit; Yoo, Cheol Min; Wang, Yuh-Shuh; Chapman, Kent D; Blancaflor, Elison B

2005-12-01

Plant development is regulated by numerous chemicals derived from a multitude of metabolic pathways. However, we know very little about the biological effects and functions of many of these metabolites in the cell. N-Acylethanolamines (NAEs) are a group of lipid mediators that play important roles in mammalian physiology. Despite the intriguing similarities between animals and plants in NAE metabolism and perception, not much is known about the precise function of these metabolites in plant physiology. In plants, NAEs have been shown to inhibit phospholipase Dalpha (PLDalpha) activity, interfere with abscisic acid-induced stomatal closure, and retard Arabidopsis seedling development. 1-Butanol, an antagonist of PLD-dependent phosphatidic acid production, was reported to induce defects in Arabidopsis seedling development that were somewhat similar to effects induced by elevated levels of NAE. This raised the possibility that the impact of NAE on seedling growth could be mediated in part via its influence on PLD activity. To begin to address this possibility, we conducted a detailed, comparative analysis of the effects of 1-butanol and N-lauroylethanolamine (NAE 12:0) on Arabidopsis root cell division, in vivo cytoskeletal organization, seed germination, and seedling growth. Although both NAE 12:0 and 1-butanol induced profound cytoskeletal and morphological alterations in seedlings, there were distinct differences in their overall effects. 1-Butanol induced more pronounced modifications in cytoskeletal organization, seedling growth, and cell division at concentrations severalfold higher than NAE 12:0. We propose that these compounds mediate their differential effects on cellular organization and seedling growth, in part through the differential modulation of specific PLD isoforms.

Effects of liquid fertilizer application on the morphology and outplanting success of container longleaf pine seedlings

Treesearch

D. Paul Jackson; R. Kasten Dumroese; James P. Barnett; William B. Patterson

2010-01-01

Of a range of fertilization rates (0.5, 1.0, 2.0, 3.0, and 4.0 mg nitrogen (N) per seedling per week) applied for 20 weeks, the 2.0-N and 3.0-N seedlings produced good root collar diameter (RCD) growth (6.9 and 7.1 mm, respectively) and needle length ≤ 30 cm. Root collar development did not differ significantly in seedlings receiving the 4.0-mg-N treatment from those...

Continuous Spectrum LEDs Promote Seedling Quality Traits and Performance of Quercus ithaburensis var. macrolepis

PubMed Central

Smirnakou, Sonia; Ouzounis, Theoharis; Radoglou, Kalliopi M.

2017-01-01

Regulation of the growth, development, and quality of plants by the control of light quality has attracted extensive attention worldwide. The aim of this study was to examine the effects of continuous LED spectrum for indoor plant pre-cultivation and to investigate the morphological and physiological responses of a common broadleaved tree species in Mediterranean environment, Quercus ithaburensis var. macrolepis at seedling developmental stage. Thus, the seedlings were pre-cultivated for 28 days, under five different LED light qualities: (1) Fluorescent (FL) as control light (2) L20AP67 (high in green and moderate in far-red), (3) AP673L (high in green and red), (4) G2 (highest in red and far-red), AP67 (high in blue, red, and far-red), and (5) NS1 (highest in blue and green and lowest in far-red) LEDs. Further examination was held at the nursery for 1 year, on several seedling quality traits. Indeed, AP67 and AP673L triggered higher leaf formation, while L20AP67 positively affected seedling shoot development. NS1 and AP67 LED pre-cultivated seedlings showed significantly higher root fibrosity than those of FL light. Furthermore, NS1 and AP673L LEDs induced fourfold increase on seedling root dry weight than FL light. Hence, evaluating the seedling nursery performance attributes, most of those photomorphogenetic responses previously obtained were still detectable. Even more so, LED pre-cultivated seedlings showed higher survival and faster growth indicating better adaptation even under natural light conditions, a fact further reinforced by the significantly higher Dickson’s quality index acquired. In conclusion, the goal of each nursery management program is the production of high quality seedlings with those desirable traits, which in turn satisfy the specific needs for a particular reforestation site. Thus, the enhanced oak seedling quality traits formed under continuous LEDs spectrum especially of NS1 and AP673L pre-cultivation may potentially fulfill this goal. PMID:28261244

Predicting the size and elevation of future mountain forests: Scaling macroclimate to microclimate

NASA Astrophysics Data System (ADS)

Cory, S. T.; Smith, W. K.

2017-12-01

Global climate change is predicted to alter continental scale macroclimate and regional mesoclimate. Yet, it is at the microclimate scale that organisms interact with their physiochemical environments. Thus, to predict future changes in the biota such as biodiversity and distribution patterns, a quantitative coupling between macro-, meso-, and microclimatic parameters must be developed. We are evaluating the impact of climate change on the size and elevational distribution of conifer mountain forests by determining the microclimate necessary for new seedling survival at the elevational boundaries of the forest. This initial life stage, only a few centimeters away from the soil surface, appears to be the bottleneck to treeline migration and the expansion or contraction of a conifer mountain forest. For example, survival at the alpine treeline is extremely rare and appears to be limited to facilitated microsites with low sky exposure. Yet, abundant mesoclimate data from standard weather stations have rarely been scaled to the microclimate level. Our research is focusing on an empirical downscaling approach linking microclimate measurements at favorable seedling microsites to the meso- and macro-climate levels. Specifically, mesoclimate values of air temperature, relative humidity, incident sunlight, and wind speed from NOAA NCEI weather stations can be extrapolated to the microsite level that is physiologically relevant for seedling survival. Data will be presented showing a strong correlation between incident sunlight measured at 2-m and seedling microclimate, despite large differences from seedling/microsite temperatures. Our downscaling approach will ultimately enable predictions of microclimate from the much more abundant mesoclimate data available from a variety of sources. Thus, scaling from macro- to meso- to microclimate will be possible, enabling predictions of climate change models to be translated to the microsite level. This linkage between measurement scales will enable a more precise prediction of the effects of climate change on the future extent and elevational distribution of our mountain forests and an accompanying array of critical ecosystem services.

Seedling Responses to Water Pulses in Shrubs with Contrasting Histories of Grassland Encroachment

PubMed Central

Woods, Steven R.; Archer, Steven R.; Schwinning, Susan

2014-01-01

Woody plant encroachment into grasslands has occurred worldwide, but it is unclear why some tree and shrub species have been markedly more successful than others. For example, Prosopis velutina has proliferated in many grasslands of the Sonoran Desert in North America over the past century, while other shrub species with similar growth form and life history, such as Acacia greggii, have not. We conducted a glasshouse experiment to assess whether differences in early seedling development could help explain why one species and not the other came to dominate many Sonoran Desert grasslands. We established eight watering treatments mimicking a range of natural precipitation patterns and harvested seedlings 16 or 17 days after germination. A. greggii had nearly 7 times more seed mass than P. velutina, but P. velutina emerged earlier (by 3.0±0.3 d) and grew faster (by 8.7±0.5 mg d−1). Shoot mass at harvest was higher in A. greggii (99±6 mg seedling−1) than in P. velutina (74±2 mg seedling−1), but there was no significant difference in root mass (54±3 and 49±2 mg seedling−1, respectively). Taproot elongation was differentially sensitive to water supply: under the highest initial watering pulse, taproots were 52±19 mm longer in P. velutina than in A. greggii. Enhanced taproot elongation under favorable rainfall conditions could give nascent P. velutina seedlings growth and survivorship advantages by helping reduce competition with grasses and maintain contact with soil water during drought. Conversely, A. greggii's greater investment in mass per seed appeared to provide little return in early seedling growth. We suggest that such differences in recruitment traits and their sensitivities to environmental conditions may help explain ecological differences between species that are highly similar as adults and help identify pivotal drivers of shrub encroachment into grasslands. PMID:24475263

An infra-red imaging system for the analysis of tropisms in Arabidopsis thaliana seedlings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orbovic, V.; Poff, K.L.

1990-05-01

Since blue and green light will induce phototropism and red light is absorbed by phytochrome, no wavelength of visible radiation should be considered safe for any study of tropisms in etiolated seedlings. For this reason, we have developed an infra-red imaging system with a video camera with which we can monitor seedlings using radiation at wavelengths longer than 800 nm. The image of the seedlings can be observed in real time, recorded on a VCR and subsequently analyzed using the Java image analysis system. The time courses for curvature of seedlings differ in shape, amplitude, and lag time. This variabilitymore » accounts for much of the noise in the measurement of curvature for a population of seedlings.« less

The Role of the Storage Carbon of Cotyledons in the Establishment of Seedlings of Hymenaea courbaril Under Different Light Conditions

PubMed Central

SANTOS, HENRIQUE P.; BUCKERIDGE, MARCOS S.

2004-01-01

• Background and Aims Hymenaea courbaril (Leguminosae-Caesalpinioideae) is a tree species with wide distribution through all of the Neotropics. It has large seeds (approx. 5 g) with non-photosynthetic storage cotyledons rich (40 %) in a cell wall polysaccharide (xyloglucan) as a carbon reserve. Because it is found in the understorey of tropical forests, it has been considered as a shade-tolerant, late-secondary species. However, the physiological mechanisms involved in seedling establishment, especially regarding the interplay between storage and light intensity, are not understood. In this work, the ecophysiological role of this carbon cotyledon reserve (xyloglucan) is characterized, emphasizing its effects on seedling growth and development during the transition from heterotrophy to autotrophy under different light conditions. • Methods Seedlings of H. courbaril were grown in environments with different light intensities, and with or without cotyledons detached before xyloglucan mobilization. Development, growth, photosynthesis and carbon partitioning (dry mass and [14C]sucrose) were analysed in each treatment. • Key Results The detachment of cotyledons was not important for seedling survival, but resulted in a strong restriction (50 % less) of shoot growth, which was the main sink for the cotyledon carbon reserves. Carbon restriction promoted an early maturation of the photosynthetic apparatus without changes in the net CO2 fixation per unit area. The reduced surface area of the first leaves in seedlings without cotyledons was evidence of limited growth and development of seedlings in low light conditions (22 µmol m−2 s−1 photon flux). • Conclusions There is an increase in the importance of storage xyloglucan in cotyledons for H. courbaril seedling development as light intensity decreases, confirming that this polymer plays a key role in the adaptation of this species to establish successfully in the shadowed understorey of the forest. PMID:15514028

Exposure to lower red to far-red light ratios improve tomato tolerance to salt stress.

PubMed

Cao, Kai; Yu, Jie; Xu, Dawei; Ai, Kaiqi; Bao, Encai; Zou, Zhirong

2018-05-24

Red (R) and far-red (FR) light distinctly influence phytochrome-mediated initial tomato growth and development, and more recent evidence indicates that these spectra also modulate responses to a multitude of abiotic and biotic stresses. This research investigated whether different R: FR values affect tomato growth response and salinity tolerance. Tomato seedlings were exposed to different R: FR conditions (7.4, 1.2 and 0.8) under salinity stress (100 mM NaCl), and evaluated for their growth, biochemical changes, active reactive oxygen species (ROS) and ROS scavenging enzymes, pigments, rate of photosynthesis, and chlorophyll fluorescence. The results showed that under conditions of salinity, tomato seedlings subjected to a lower R: FR value (0.8) significantly increased both their growth, proline content, chlorophyll content and net photosynthesis rate (Pn), while they decreased malondialdehyde (MDA) compared to the higher R: FR value (7.4). Under conditions of salinity, the lower R: FR value caused a decrease in both the superoxide anion (O 2 •- ) and in hydrogen peroxide (H 2 O 2 ) generation, an increase in the activities of superoxidase dismutase (SOD, EC 1.15.1.1), peroxidase (POD, EC 1.11.1.7) and catalase (CAT, EC 1.11.1.7). Tomato seedlings grown under the lower R: FR value and conditions of salinity showed a higher actual quantum yield of photosynthesis (ΦPSII), electron transport rate (ETR), and photochemical quenching (qP) than those exposed to a higher R: FR, indicating overall healthier growth. However, the salinity tolerance induced at the lower R: FR condition disappeared in the tomato phyB1 mutant. These results suggest that growing tomato with a lower R: FR value could improve seedlings' salinity tolerance, and phytochrome B1 play an very important role in this process. Therefore, different qualities of light can be used to efficiently develop abiotic stress tolerance in tomato cultivation.

[Different responses of growth and root development of Schima superba provenance to the adjacent plant competition in different nutrient conditions].

PubMed

Yao, Jia Bao; Chu, Xiu Li; Zhou, Zhi Chun; Tong, Jian She; Wang, Hui; Yu, Jia Zhong

2017-04-18

Growth and root development of three Schima superba seedling provenances were influenced by adjacent plant competition in the homogeneous and heterogeneous nutrient environment, which revealed the reasons of S. superba competition differences in the different genotypes. The results indicated that, compared with homogeneous nutrient environment, all three S. superba provenances showed higher seedling height, more dry matter accumulation, and significant root proliferation in heterogeneous nutrient environment. Under heterogeneous nutrient environment, the seedlings of S. superba from Jian'ou of Fujian exhibited higher competitive advantage in growth than that of S. superba from Longquan of Zhejiang and Xinfeng of Jiangxi, especially standing out under mixed cultivation with seedlings of Cunninghamia lanceolata. Under mixed cultivation, the root growth parameters of S. superba such as root length, root surface area and volume increased by 20.4%-69.0% compared with the single plant, which enhanced the foraging ability and growth advantage. To some extent, however, the root development in Longquan of Zhejiang and Xinfeng of Jiangxi was suppressed when subjected to the pattern of mixed cultivation. Besides, the root growth and development of all three S. superba provenances were suppressed, which might be due to their root self-recognition in the pattern of mono cultivation. Therefore, the seedling growth in Jian'ou of Fujian decreased significantly, but seedling growth in Longquan of Zhejiang and Xinfeng of Jiangxi was not suppressed, even increased evidently, as their root physiological plasticity might play the crucial role in seedling growth. Hence the S. superba from Jian'ou of Fujian with high foraging efficiency and competition ability was suggested with the method of mixed forestation to improve the S. superba forest plantation productivity.

Proteomic identification of OsCYP2, a rice cyclophilin that confers salt tolerance in rice (Oryza sativa L.) seedlings when overexpressed

PubMed Central

2011-01-01

Background High Salinity is a major environmental stress influencing growth and development of rice. Comparative proteomic analysis of hybrid rice shoot proteins from Shanyou 10 seedlings, a salt-tolerant hybrid variety, and Liangyoupeijiu seedlings, a salt-sensitive hybrid variety, was performed to identify new components involved in salt-stress signaling. Results Phenotypic analysis of one protein that was upregulated during salt-induced stress, cyclophilin 2 (OsCYP2), indicated that OsCYP2 transgenic rice seedlings had better tolerance to salt stress than did wild-type seedlings. Interestingly, wild-type seedlings exhibited a marked reduction in maximal photochemical efficiency under salt stress, whereas no such change was observed for OsCYP2-transgenic seedlings. OsCYP2-transgenic seedlings had lower levels of lipid peroxidation products and higher activities of antioxidant enzymes than wild-type seedlings. Spatiotemporal expression analysis of OsCYP2 showed that it could be induced by salt stress in both Shanyou 10 and Liangyoupeijiu seedlings, but Shanyou 10 seedlings showed higher OsCYP2 expression levels. Moreover, circadian rhythm expression of OsCYP2 in Shanyou 10 seedlings occurred earlier than in Liangyoupeijiu seedlings. Treatment with PEG, heat, or ABA induced OsCYP2 expression in Shanyou 10 seedlings but inhibited its expression in Liangyoupeijiu seedlings. Cold stress inhibited OsCYP2 expression in Shanyou 10 and Liangyoupeijiu seedlings. In addition, OsCYP2 was strongly expressed in shoots but rarely in roots in two rice hybrid varieties. Conclusions Together, these data suggest that OsCYP2 may act as a key regulator that controls ROS level by modulating activities of antioxidant enzymes at translation level. OsCYP2 expression is not only induced by salt stress, but also regulated by circadian rhythm. Moreover, OsCYP2 is also likely to act as a key component that is involved in signal pathways of other types of stresses-PEG, heat, cold, or ABA. PMID:21324151

Fall nitrogen fertilization and the biology of Pinus taeda seedling development

Treesearch

Shi-Jean S. Sung; C.C. Black; T.L. Kormanik; P.A. Counce

1997-01-01

In mid-September when stems and roots of nursery-grown loblolly pine (Pinus taeda L.) seedlings are actively accumulating dry weight (DW), an extra 10, 20, or 40 kg NH4NO3 ha-1 (10N, 20N, 4ON) was applied. Seedlings receiving no extra N (0N) were the controls. The temporal patterns...

Developmental dynamics of longleaf pine seedling flushes and needles

Treesearch

Shi-Jean Susana Sung; Stanley J. Zarnoch; James D. Haywood; Daniel Leduc; Mary A. Sword-Sayer

2013-01-01

Longleaf pine (Pinus palustris Mill.) seedlings were grown for 27 weeks in containers of three cavity sizes and two cavity types (with and without copper coating) and then outplanted in central Louisiana in November 2004. Three seedlings from each plot were assessed repeatedly for shoot flush and needle development in 2007 and 2008. Cavity type had...

Food Reserves In Mountain Longleaf Pine Roots During Shoot Elongation

Treesearch

Charles H. Walkinshaw; William J. Otrosina

2002-01-01

Abstract - Survival and growth of longleaf pine seedlings depends upon a well-developed root system. Soil moisture is also critical for the seedling to emerge from the grass-stage. When longleaf pine seedlings emerge from the grass stage, they grow rapidly in height and diameter. Branches are often few in number and, if present, may have low...

Recovery of l-year-old loblolly pine seedlings from simulated browse damage

Treesearch

Michael G. Shelton; Michael D. Cain

2002-01-01

Loblolly pine (Pinus taeda L.) seedlings are frequently browsed by a wide variety of animals during the first few years of their development. Although anecdotal observations indicate that the potential for seedling recovery is good, there is little quantitative information on the factors affecting the recovery process. Thus, we conducted a study to...

The Association of a Longidorus Species with Stunting and Root Damage of Loblolly Pine (Pinus taeda L.) Seedlings

Treesearch

Stephen W. Fraedrich; Michelle M. Cram

2002-01-01

A Longidorus species was consistently associated with patches of stunted and chlorotic loblolly pine seedlings at a forest-tree nursery in Georgia. Seedlings from affected areas had poorly developed root systems that lacked lateral and feeder roots. Longidorus population densities in composite soil samples from the margins of...

Benomyl Stimulates Ectomycorrhizal Development by Pisolithus Tinctorius on Shortleaf Pine Grown in Containers

Treesearch

William H. Pawuk; James P. Barnett

1981-01-01

Container-grown shortleaf pine (Pinus echinata Mill.) seedlings inoculated with Pisolithus tinctorius and drenched with benomyl formed more mycorrhizal roots than undrenched seedlings. Seedlings were drenched (2.5, 5, and 10 mg ai in 15 ml of water per individual) prior to sowing and at either 2-, 4-, or 8-week intervals....

Reduction of methylviologen-mediated oxidative stress tolerance in antisense transgenic tobacco seedlings through restricted expression of StAPX.

PubMed

Sun, Wei-Hong; Wang, Yong; He, Hua-Gang; Li, Xue; Song, Wan; Du, Bin; Meng, Qing-Wei

2013-07-01

Ascorbate peroxidases are directly involved in reactive oxygen species (ROS) scavenging by reducing hydrogen peroxide to water. The tomato thylakoid-bound ascorbate peroxidase gene (StAPX) was introduced into tobacco. RNA gel blot analysis confirmed that StAPX in tomato leaves was induced by methylviologen-mediated oxidative stress. The sense transgenic seedlings exhibited higher tAPX activity than that of the wild type (WT) plants under oxidative stress conditions, while the antisense seedlings exhibited lower tAPX activity. Lower APX activities of antisense transgenic seedlings caused higher malondialdehyde contents and relative electrical conductivity. The sense transgenic seedlings with higher tAPX activity maintained higher chlorophyll content and showed the importance of tAPX in maintaining the optimal chloroplast development under methylviologen stress conditions, whereas the antisense lines maintained lower chlorophyll content than WT seedlings. Results indicated that the over-expression of StAPX enhanced tolerance to methylviologen-mediated oxidative stress in sense transgenic tobacco early seedlings, whereas the suppression of StAPX in antisense transgenic seedlings showed high sensitivity to oxidative stress.

Triticale powdery mildew: population characterization and wheat gene efficiency.

PubMed

Bouguennec, Annaig; Trottet, Maxime; du Cheyron, Philippe; Lonnet, Philippe

2014-01-01

Powdery mildew has emerged on triticale in the early 2000s in many locations, probably due to a host range expansion of the wheat formae speciales, Blumeria graminis f.sp. tritici. Many triticale cultivars are highly susceptible to powdery mildew, mainly in seedling stage, revealing a probably narrow genetic basis for powdery mildew resistance genes (Pm). Moreover, as Blumeria graminis is an obligate biotrophic fungus, it is very time consuming and difficult to maintain powdery mildew isolates for a non-specialized laboratory and populations can evolve. In order to identify wheat Pm genes efficient against natural populations of powdery mildew, wheat differential hosts and triticale seedlings were inoculated below susceptible triticale crop naturally contaminated by mildew, in several locations and several years. Symptoms on seedlings were measured after approximately two weeks of incubation in favorable fungus growth conditions. According to these data, we classified the Pm genes presents in our wheat differential hosts set in 3 classes: Pm already overcame by triticale powdery mildew, Pm having variable effects and Pm still efficient against triticale mildew. Data on triticale seedlings allowed us to identify some few triticale cultivars resistant to Blumeria graminis in seedling stage. We will try to identify Pm genes present in those cultivars next year by testing them with the characterized isolates of powdery mildew from Gent University. Nevertheless, interspecific crossing of wheat, resistant to powdery mildew in seedling stage, and rye have been initiated to introduce potentially interesting genes for resistance in triticale.

Do key dimensions of seed and seedling functional trait variation capture variation in recruitment probability?

PubMed

Larson, Julie E; Sheley, Roger L; Hardegree, Stuart P; Doescher, Paul S; James, Jeremy J

2016-05-01

Seedling recruitment is a critical driver of population dynamics and community assembly, yet we know little about functional traits that define different recruitment strategies. For the first time, we examined whether trait relatedness across germination and seedling stages allows the identification of general recruitment strategies which share core functional attributes and also correspond to recruitment outcomes in applied settings. We measured six seed and eight seedling traits (lab- and field-collected, respectively) for 47 varieties of dryland grasses and used principal component analysis (PCA) and cluster analysis to identify major dimensions of trait variation and to isolate trait-based recruitment groups, respectively. PCA highlighted some links between seed and seedling traits, suggesting that relative growth rate and root elongation rate are simultaneously but independently associated with seed mass and initial root mass (first axis), and with leaf dry matter content, specific leaf area, coleoptile tissue density and germination rate (second axis). Third and fourth axes captured separate tradeoffs between hydrothermal time and base water potential for germination, and between specific root length and root mass ratio, respectively. Cluster analysis separated six recruitment types along dimensions of germination and growth rates, but classifications did not correspond to patterns of germination, emergence or recruitment in the field under either of two watering treatments. Thus, while we have begun to identify major threads of functional variation across seed and seedling stages, our understanding of how this variation influences demographic processes-particularly germination and emergence-remains a key gap in functional ecology.

Total ammoniacal nitrogen biofiltration of wastewaters from aquaculture systems using Macrocystis spp.

PubMed

Bravo, R; Segovia, E; Guerrero, L; Montalvo, S; Barahona, A; Borja, R

2013-01-01

The results of total ammoniacal nitrogen (NH(3) + NH(4) (+)) removal in aquaculture systems using two experimental sets, aquatic seedlings produced in laboratory controlled conditions and wild seaweed (Macrocystis spp.) in reproductive state, are shown in this work. Biofiltration assays were carried out using a load of total ammoniacal nitrogen (TAN) of 1 mg/L. Absorption rates were measured taking into account a previous surface characterization, which gave values of 44 ± 14 cm(2)/g and 18 ± 6 cm(2)/g for aquatic seedlings and wild algae, respectively. The following parameters were measured during the experimental runs: temperature, pH, O(2), illuminance or light intensity, salinity and total solids. TAN removals of 61% and 70% were achieved for the seedlings and Macrocystis spp., respectively, after 17 h of treatment. The TAN absorption results were expressed as a function of surface and mass achieving the following values: 3.0 nmol N cm(-2) h(-1) and 111 nmol N g(-1) h(-1) for the seedlings, and 6.9 nmol N cm(-2) h(-1) and 122.4 nmol N g(-1) h(-1) for the macroalgae. In the light of these biofiltration processes, the initial TAN concentration decreased by 90% for the seedlings and wild algae over approximately 110 and 41 h, respectively. In addition, TAN removals achieved with Macrocystis spp. were always higher than those obtained with aquatic seedlings for the same operating periods.

Phytotoxicity of glyphosate in the germination of Pisum sativum and its effect on germinated seedlings

PubMed Central

2017-01-01

The present study evaluated the effects of glyphosate on Pisum sativum germination as well as its effect on the physiology and biochemistry of germinated seedlings. Different physico-chemical biomarkers, viz., chlorophyll, root and shoot length, total protein and soluble sugar, along with sodium and potassium concentration, were investigated in germinated seedlings at different glyphosate concentrations. This study reports the influence of different concentrations of glyphosate on pea seeds and seedlings. Physicochemical biomarkers were significantly changed by glyphosate exposure after 15 days. The germination of seedlings under control conditions (0 mg/L) was 100% after 3 days of treatment but at 3 and 4 mg/L glyphosate, germination was reduced to 55 and 40%, respectively. Physiological parameters like root and shoot length decreased monotonically with increasing glyphosate concentration, at 14 days of observation. Average root and shoot length (n=30 in three replicates) were reduced to 14.7 and 17.6%, respectively, at 4 mg/L glyphosate. Leaf chlorophyll content also decreased, with a similar trend to root and shoot length, but the protein content initially decreased and then increased with an increase in glyphosate concentration to 3 mg/L. The study suggests that glyphosate reduces the soluble sugar content significantly, by 21.6% (v/v). But internal sodium and potassium tissue concentrations were significantly altered by glyphosate exposure with increasing concentrations of glyphosate. Biochemical and physiological analysis also supports the inhibitory effect of glyphosate on seed germination and biochemical effects on seedlings. PMID:28728354

Heat shock protein Hsp90-2 expression in the Arabidopsis thaliana seedlings under clinorotation

NASA Astrophysics Data System (ADS)

Kozeko, Liudmyla

Heat shock proteins 90 kDa (Hsp90) are abundant under normal conditions and induced by stress. This family is distinguished from other chaperones in that most of its substrates are signal transduction proteins. Previously, we determined some time-dependent increase in the Hsp90 level in pea seedlings in response to simulated microgravity that indicated a stress-reaction. However, expression of the individual members of the Hsp90 family have specific pattern. The purpose of this study was to investigate possible alterations in the gene expression pattern of cytosolic Hsp90-2 in Arabidopsis thaliana seedlings under 2D-clinorotation. To obtain detailed expression pattern of the HSP90-2 genes we used seeds that provides a resource of loss-of-function mutations gene expression patterns via translational fusions with the reporter gene, GUS (a line N 166718, NASC). There were two variants of the experiment: 1) seedlings grew under clinorotation for 10, 12, 14 d; 2) seedlings grew in the stationary conditions for 10 d followed by clinorotation for 3 h -at 22o C and 16h light cycle. The seedlings grown in the stationary conditions were used as a control. GUS staining showed that HSP90-2 expression was regulated during seedling development and affected by clinorotation in the heterozygous mutant plants. In the homozygous for the mutation plants, HSP90-2 expression was stable during seedling development and not affected by clinorotation. GUS staining was observed in cotyledons, leaves and hypocotyls of the seedlings (especially intense in vascular bundles), indicating intensive cellular processes with participation of this chaperone. Possible pathways of influence of clinorotation on HSP90-2 expression are discussed.

Xylem development and cell wall changes of soybean seedlings grown in space.

PubMed

de Micco, Veronica; Aronne, Giovanna; Joseleau, Jean-Paul; Ruel, Katia

2008-04-01

Plants growing in altered gravity conditions encounter changes in vascular development and cell wall deposition. The aim of this study was to investigate xylem anatomy and arrangement of cellulose microfibrils in vessel walls of different organs of soybean seedlings grown in Space. Seeds germinated and seedlings grew for 5 d in Space during the Foton-M2 mission. The environmental conditions, other than gravity, of the ground control repeated those experienced in orbit. The seedlings developed in space were compared with those of the control test on the basis of numerous anatomical and ultrastructural parameters such as number of veins, size and shape of vessel lumens, thickness of cell walls and deposition of cellulose microfibrils. Observations made with light, fluorescence and transmission electron microscopy, together with the quantification of the structural features through digital image analysis, showed that the alterations due to microgravity do not occur at the same level in the various organs of soybean seedlings. The modifications induced by microgravity or by the indirect effect of space-flight conditions, became conspicuous only in developing vessels at the ultrastructural level. The results suggested that the orientation of microfibrils and their assembly in developing vessels are perturbed by microgravity at the beginning of wall deposition, while they are still able to orient and arrange in thicker and ordered structures at later stages of secondary wall deposition. The process of proper cell-wall building, although not prevented, is perturbed in Space at the early stage of development. This would explain the almost unaltered anatomy of mature structures, accompanied by a slower growth observed in seedlings grown in Space than on Earth.

Xylem Development and Cell Wall Changes of Soybean Seedlings Grown in Space

PubMed Central

de Micco, Veronica; Aronne, Giovanna; Joseleau, Jean-Paul; Ruel, Katia

2008-01-01

Background and Aims Plants growing in altered gravity conditions encounter changes in vascular development and cell wall deposition. The aim of this study was to investigate xylem anatomy and arrangement of cellulose microfibrils in vessel walls of different organs of soybean seedlings grown in Space. Methods Seeds germinated and seedlings grew for 5 d in Space during the Foton-M2 mission. The environmental conditions, other than gravity, of the ground control repeated those experienced in orbit. The seedlings developed in space were compared with those of the control test on the basis of numerous anatomical and ultrastructural parameters such as number of veins, size and shape of vessel lumens, thickness of cell walls and deposition of cellulose microfibrils. Key Results Observations made with light, fluorescence and transmission electron microscopy, together with the quantification of the structural features through digital image analysis, showed that the alterations due to microgravity do not occur at the same level in the various organs of soybean seedlings. The modifications induced by microgravity or by the indirect effect of space-flight conditions, became conspicuous only in developing vessels at the ultrastructural level. The results suggested that the orientation of microfibrils and their assembly in developing vessels are perturbed by microgravity at the beginning of wall deposition, while they are still able to orient and arrange in thicker and ordered structures at later stages of secondary wall deposition. Conclusions The process of proper cell-wall building, although not prevented, is perturbed in Space at the early stage of development. This would explain the almost unaltered anatomy of mature structures, accompanied by a slower growth observed in seedlings grown in Space than on Earth. PMID:18252765

Automated analysis of hypocotyl growth dynamics during shade avoidance in Arabidopsis.

PubMed

Cole, Benjamin; Kay, Steve A; Chory, Joanne

2011-03-01

Plants that are adapted to environments where light is abundant are especially sensitive to competition for light from neighboring vegetation. As a result, these plants initiate a series of changes known as the shade avoidance syndrome, during which plants elongate their stems and petioles at the expense of leaf development. Although the developmental outcomes of exposure to prolonged shade are known, the signaling dynamics during the initial exposure of seedlings to shade is less well studied. Here, we report the development of a new software-based tool, called HyDE (Hypocotyl Determining Engine) to measure hypocotyl lengths of time-resolved image stacks of Arabidopsis wild-type and mutant seedlings. We show that Arabidopsis grows rapidly in response to the shade stimulus, with measurable growth after just 45 min shade exposure. Similar to other mustard species, this growth response occurs in multiple distinct phases, including two phases of rapid growth and one phase of slower growth. Using mutants affected in shade avoidance phenotypes, we demonstrate that most of this early growth requires new auxin biosynthesis via the indole-3-pyruvate pathway. When activity of this pathway is reduced, the first phase of elongation growth is absent, and this is correlated with reduced activity of auxin-regulated genes. Finally, we show that varying shade intensity and duration can affect the shape and magnitude of the growth response, indicating a broad range of the elongation response to shade. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

Influence of nonuniform magnetic fields on orientation of plant seedlings in microgravity conditions

NASA Astrophysics Data System (ADS)

Nechitailo, G. S.; Mashinsky, A. L.; Kuznetsov, A. A.; Chikov, V. M.; Kuznetsov, O. A.

2001-01-01

Experiments on the spatial behavior of the flax ( Linum usitatissimum, L.) seedlings in a nonuniform magnetic field were conducted on the orbital space stations «Salutå and «Mirå. This field can displace sensory organelles (statoliths) inside receptor cells and such displacement should cause a physiological reaction of the plant - tropistic curvature. Experiments were conducted in the custom-built «Magnetogravistatå facility, where seeds were germinated and grown for 3-4 days in a magnetic field with the dynamic factor grad(H 2/2)≈ 10 7 Oe 2/cm, then fixed on orbit and returned to Earth for analysis. It was found, that 93% of the seedlings were oriented in the field consistently with curvature in response to displacement of statoliths along the field gradient by ponderomotive magnetic forces, while control seedlings grew in the direction of the initial orientation of the seed. This suggests, that gravity receptors of plants recognized magnetic forces on statoliths as gravity, and that gravity stimulus can be substituted for plants by a force of a different physical nature.

[Allelopathy autotoxicity effects of aquatic extracts from rhizospheric soil on rooting and growth of stem cuttings in Pogostemon cablin].

PubMed

Tang, Kun; Li, Ming; Dong, Shan; Li, Yun-qi; Huang, Jie-wen; Li, Long-ming

2014-06-01

To study the allelopathy effects of aquatic extracts from rhizospheric soil on the rooting and growth of stem cutting in Pogostemon cablin, and to reveal its mechanism initially. The changes of rhizogenesis characteristics and physic-biochemical during cutting seedlings were observed when using different concentration of aquatic extracts from rhizospheric soil. Aquatic extracts from rhizospheric soil had significant inhibitory effects on rooting rate, root number, root length, root activity, growth rate of cutting with increasing concentrations of tissue extracts; The chlorophyll content of cutting seedlings were decreased, but content of MDA were increased, and activities of POD, PPO and IAAO in cutting seedlings were affected. Aquatic extracts from rhizospheric soil of Pogostemon cablin have varying degrees of inhibitory effects on the normal rooting and growth of stem cuttings.

Nursery cultural practices to achieve targets: A case study in western larch irrigation

Treesearch

Anthony S. Davis; Robert F. Keefe

2011-01-01

Nursery cultural practices are used to help growers achieve pre-determined size and physiological targets for seedlings. In that regard, irrigation is used to accelerate or slow growth and as a trigger for changing growth phase. In a case study highlighting the effects of irrigation on seedling development, western larch (Larix occidentalis Nutt.) seedlings were grown...

Production and early field performance of RPM® seedlings in Missouri floodplains

Treesearch

Daniel C. Dey; Wayne Lovelace; John M. Kabrick; Michael A. Gold

2004-01-01

A new nursery culture process has been developed to produce large container RPM? seedlings in an effort to improve the success in artificially regenerating hardwoods. Major features of the process include air root pruning of seedlings grown in a well aerated soil medium to encourage a dense, fibrous root system. Production has focused on native bottomland tree, shrub,...

Irrigating and fertilizing to grow better nursery seedlings

Treesearch

Paul P. Kormanik; Shi-Jean S. Sung; T.L. Kormanik

1994-01-01

In this paper we describe a system for producing excellent loblolly pine seedling for planting in southern forests. The system, which has taken years to develop, appears to be working well. Proof of that will depend upon results of outplanting tests, but there are strong indications that the seedlings we are producing will be better than those coming from most...

Development and plasticity of endangered shrub Lindera melissifolia (Lauraceae) seedlings under contrasting light regimes

Treesearch

Brian R Lockhart; Emile S Gardiner; Theran Stautz; Theodor D. Leininger

2012-01-01

Lindera melissifolia (Walt.) Blume seedlings were raised in a growth chamber to determine the effects of light availability on shoot growth pattern, and basic leaf and stem growth. Lindera melissifolia seedlings exhibited a sympodial shoot growth pattern for 3 months following emergence from the soil medium, but this pattern was characterized by a reduction in leaf...

Relating Pine Seed Coat Characteristics to Speed of Germination, Geographic Variation, and Seedling Development

Treesearch

James P. Barnett

1998-01-01

The influence of seed size and weight on early seedling growth of tree species has been studied for over 50 years. Righter (1945) found that, in the genus Pinus, the positive correlation between seed weight and seedling height was temporary and disappeared after time in the field. A more recent study with loblolly pine (Pinus taeda...

Development of Longleaf Pine Seedlings Under Parent Trees

Treesearch

William D. Boyer

1963-01-01

In southwest Alabama, unburned seedlings under overstories ranging up to 90 square feet of basal area per acre survived as well as those with no tree competition. After 7 years, milacre stocking averaged 99 percent and survival 72 percent. Growth, but not survival, improved with distance from parent trees. Seedlings under tree crowns had less brown spot than those in...

Short-day treatment alters Douglas-fir seedling dehardening and transplant root proliferation at varying rhizosphere temperatures

Treesearch

Douglass F. Jacobs; Anthony S. Davis; BArrett C. Wilson; R. Kasten Dumroese; Rosa C. Goodman; K. Francis Salifu

2008-01-01

We tested effects of shortened day length during nursery culture on Douglis-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) seedling development at dormancy release. Seedlings from a 42 N source were grown either under ambient photoperiods (long-day (LD)) or with a 28 day period of 9 h light: 15 h dark photoperiods (short...

Regression models for estimating leaf area of seedlings and adult individuals of Neotropical rainforest tree species.

PubMed

Brito-Rocha, E; Schilling, A C; Dos Anjos, L; Piotto, D; Dalmolin, A C; Mielke, M S

2016-01-01

Individual leaf area (LA) is a key variable in studies of tree ecophysiology because it directly influences light interception, photosynthesis and evapotranspiration of adult trees and seedlings. We analyzed the leaf dimensions (length - L and width - W) of seedlings and adults of seven Neotropical rainforest tree species (Brosimum rubescens, Manilkara maxima, Pouteria caimito, Pouteria torta, Psidium cattleyanum, Symphonia globulifera and Tabebuia stenocalyx) with the objective to test the feasibility of single regression models to estimate LA of both adults and seedlings. In southern Bahia, Brazil, a first set of data was collected between March and October 2012. From the seven species analyzed, only two (P. cattleyanum and T. stenocalyx) had very similar relationships between LW and LA in both ontogenetic stages. For these two species, a second set of data was collected in August 2014, in order to validate the single models encompassing adult and seedlings. Our results show the possibility of development of models for predicting individual leaf area encompassing different ontogenetic stages for tropical tree species. The development of these models was more dependent on the species than the differences in leaf size between seedlings and adults.

Effect of microgravity on stress ethylene and carbon dioxide production in sweet clover (Melilotus alba L.)

NASA Technical Reports Server (NTRS)

Gallegos, Gregory L.; Odom, William R.; Guikema, James A.

1995-01-01

The study of higher plant growth and development in the microgravity (micro-g) environment continues to be a challenge. This is in part a result of the available flight qualified hardware with restrictive closed gas environments. This point is underscored by considering that gas exchange of seedlings grown in microgravity may be further limited owing to a thicker layer of water wicked onto the roots and to the absence of convective mixing. We hypothesized that seedlings grown under such conditions will experience greater hypoxia in microgravity than at Earth gravity, and thus produce greater stress ethylene. We compared flight and ground samples of sweet clover seedlings grown in the Fluid Processing Apparatus (FPA) during STS-57 and found them to contain extremely high levels of carbon dioxide (CO2) and stress ethylene. There were time dependent increases for both gases, and seedling growth was greatly inhibited. We repeated these experiments aboard STS-60 using modified chambers which increased, by fifty fold, the air available to the developing seedlings. Sweet clover seed germination and subsequent seedling growth to eight days within the FPA modified with a gas permeable membrane is not compromised by the microgravity environment.

Biometric anatomy of seedlings developed onboard of Foton-M2 in an automatic system supporting growth

NASA Astrophysics Data System (ADS)

De Micco, Veronica; Aronne, Giovanna

2008-04-01

During the evolution of higher plants on Earth, changes in numerous environmental factors occurred, but gravity has been a steady and unchanging force. The alteration of gravitational stimulus can cause modification of plant growth in various aspects that need to be investigated before the establishment of self-sustaining human colonies in Space, supported by bio-regenerative systems. This paper reports the results of an experiment conducted onboard of Foton-M2 satellite where soy seedlings grew during a 5-days period. The experiment was aimed to investigate the effect of microgravity on seed germination, seedling development, morphology and anatomy. The environmental conditions, other than gravity, of the ground control were repeated as identical as possible to those experienced on orbit. Seedlings developed in Space were compared with those grown in 1 g on the basis of numerous anatomical and cytological parameters, such as size and shape of cells and intercellular spaces, amount and distribution of starch and phenolics in different organs and tissues. The observations made through light and fluorescence microscopy, together with the quantification of structural features, by means of digital image analysis, allowed to evidence that the various organs and tissues of soy seedlings show different degrees of alteration after the development in microgravity.

Gibberellin Biosynthesis in Developing Pumpkin Seedlings12

PubMed Central

Lange, Theo; Kappler, Jeannette; Fischer, Andreas; Frisse, Andrea; Padeffke, Tania; Schmidtke, Sabine; Lange, Maria João Pimenta

2005-01-01

A gibberellin (GA) biosynthetic pathway was discovered operating in root tips of 7-d-old pumpkin (Cucurbita maxima) seedlings. Stepwise analysis of GA metabolism in cell-free systems revealed the conversion of GA12-aldehyde to bioactive GA4 and inactive GA34. Highest levels of endogenous GA4 and GA34 were found in hypocotyls and root tips of 3-d-old seedlings. cDNA molecules encoding two GA oxidases, CmGA20ox3 and CmGA3ox3, were isolated from root tips of 7-d-old LAB150978-treated seedlings. Recombinant CmGA20ox3 fusion protein converted GA12 to GA9, GA24 to GA9, GA14 to GA4, and, less efficiently, GA53 to GA20, and recombinant CmGA3ox3 protein oxidized GA9 to GA4. Transcript profiles were determined for four GA oxidase genes from pumpkin revealing relatively high transcript levels for CmGA7ox in shoot tips and cotyledons, for CmGA20ox3 in shoot tips and hypocotyls, and for CmGA3ox3 in hypocotyls and roots of 3-d-old seedlings. Transcripts of CmGA2ox1 were mainly found in roots of 7-d-old seedlings. In roots of 7-d-old seedlings, transcripts of CmGA7ox, CmGA20ox3, and CmGA3ox3 were localized in the cap and the rhizodermis by in situ hybridization. We conclude that hypocotyls and root tips are important sites of GA biosynthesis in the developing pumpkin seedling. PMID:16126862

Challenges in forest reclamation of marginal lands: a balance between site conditions and seedling quality

NASA Astrophysics Data System (ADS)

Landhäusser, Simon

2017-04-01

Forest loss and degradation is occurring worldwide, but at the same time efforts in forest restoration are ever increasing. While approaches to restoration often follow specific stakeholder objectives, regional climates and the degree of site degradation also play an important role in the prioritization of restoration efforts. Often the restoration of degraded lands can satisfy only few measurable objectives; however, to design and restore resistant and resilient ecosystems that can adapt to changing conditions, there is a need for new and adaptive management approaches. Mining and other resource extraction industries are affecting more and more forested areas worldwide. A priority in the reclamation and certification of forest lands disturbed by industrial activity is their expeditious redevelopment to functioning forests. To rehabilitate these heavily disturbed areas back to forest ecosystems, planting of trees remains one of the most effective strategies for the redevelopment of a continuous tree canopy on a site. It is well understood that access to good quality seedling stock is essential to achieve establishment success and early growth of seedlings. However, most reclamation areas have challenging initial site conditions and these conditions are often not a single factor but a combination of factors that can be additive or synergistic. Therefore successful forest restoration on degraded lands needs to consider multiple objectives and approaches to minimize trade-offs in achieving these objectives. To meet these demands, new methods for the production and evaluation of seedling stock types are needed to ensure that that seedlings are fit to grow on a wide range of site conditions or are particularly designed to grow in very specific conditions. Generally, defining seedling quality is difficult as it is species specific and results have been mixed; likely influenced by site conditions, further reiterating the need to carefully evaluate sites allowing appropriate seedling qualities to be identified. In this presentation, I will show results from a range of studies that explored the role of seedling characteristics in response to challenging site conditions and explore the need for a balance between the recognition and improvement of limiting site conditions and the availability of quality seedling stock in forest restoration.

Tree recruitment and survival in rivers: Influence of hydrological process

USGS Publications Warehouse

Dorava, J.M.; Milner, A.M.

2000-01-01

The findings of a 14-year study of tree reproduction and survival in the Platte River, Nebraska, are presented. The study was initiated in 1985 to determine the causes and remedies of woodland expansion and channel narrowing, which have reduced potential roosting habitat for migratory avifauna such as the whooping crane and sandhill crane. A total of 296 relocatable sites, constituting some 600 plots with Populus and Salix seedlings, was selected and sampled within two reaches near Shelton and Odessa, Nebraska. The fate of some 37 000 tree seedlings was monitored within the plot network. Tree recruitment is controlled largely by stream flow in June. Populus and Salix produce large numbers of seedlings in the river bed in most years, indicating the potential for high rates of woodland expansion. On average, in only 1 year in 7 is stream flow in June high enough to preclude Populus and Salix recruitment. Seedling mortality is dominated by two environmental factors: summer stream flow pulses from thunderstorms, which erode or bury new germinants, and river bed restructuring by moving ice in winter. A third factor, seedling mortality by desiccation during summer droughts, does occur but at a low frequency. Plots of seedlings had extremely low survival rates over the course of the study. Forty-two per cent of the plots lost all seedlings by the first remeasurement (July to September), 36% by the second measurement (May), and 10% by the third remeasurement (July). Thus nearly 90% of the plots had lost all tree seedlings by the end of the first year. These results explain why the Platte River has come into dynamic equilibrium with respect to the balance between active channel and woodland area. Low rates of new woodland expansion are counterbalanced by erosion of established woodland. The demographic approach to studying ecohydrology can be adapted to monitor the effectiveness of prescribed flows as insurance against future narrowing. Flows prescribed at key times to raise seedling mortality rates are recommended to maintain or widen channels, rather than mechanical clearing of established woodland. Copyright ?? 2000 John Wiley & Sons, Ltd.

Tree recruitment and survival in rivers: influence of hydrological processes

NASA Astrophysics Data System (ADS)

Carter Johnson, W.

2000-10-01

The findings of a 14-year study of tree reproduction and survival in the Platte River, Nebraska, are presented. The study was initiated in 1985 to determine the causes and remedies of woodland expansion and channel narrowing, which have reduced potential roosting habitat for migratory avifauna such as the whooping crane and sandhill crane.A total of 296 relocatable sites, constituting some 600 plots with Populus and Salix seedlings, was selected and sampled within two reaches near Shelton and Odessa, Nebraska. The fate of some 37 000 tree seedlings was monitored within the plot network.Tree recruitment is controlled largely by stream flow in June. Populus and Salix produce large numbers of seedlings in the river bed in most years, indicating the potential for high rates of woodland expansion. On average, in only 1 year in 7 is stream flow in June high enough to preclude Populus and Salix recruitment.Seedling mortality is dominated by two environmental factors: summer stream flow pulses from thunderstorms, which erode or bury new germinants, and river bed restructuring by moving ice in winter. A third factor, seedling mortality by desiccation during summer droughts, does occur but at a low frequency.Plots of seedlings had extremely low survival rates over the course of the study. Forty-two per cent of the plots lost all seedlings by the first remeasurement (July to September), 36% by the second measurement (May), and 10% by the third remeasurement (July). Thus nearly 90% of the plots had lost all tree seedlings by the end of the first year.

7 CFR 201.56 - Interpretation.

Code of Federal Regulations, 2012 CFR

2012-01-01

... considered to have germinated when it has developed those essential structures which, for the kind of seed.... In general, the following are considered to be essential structures necessary for the continued development of the seedling (although some structures may not be visible in all kinds at the time of seedling...

7 CFR 201.56 - Interpretation.

Code of Federal Regulations, 2014 CFR

2014-01-01

... considered to have germinated when it has developed those essential structures which, for the kind of seed.... In general, the following are considered to be essential structures necessary for the continued development of the seedling (although some structures may not be visible in all kinds at the time of seedling...

Regulation of root development in Arabidopsis thaliana by phytohormone-secreting epiphytic methylobacteria.

PubMed

Klikno, Jana; Kutschera, Ulrich

2017-09-01

In numerous experimental studies, seedlings of the model dicot Arabidopsis thaliana have been raised on sterile mineral salt agar. However, under natural conditions, no plant has ever grown in an environment without bacteria. Here, we document that germ-free (gnotobiotic) seedlings, raised on mineral salt agar without sucrose, develop very short root hairs. In the presence of a soil extract that contains naturally occurring microbes, root hair elongation is promoted; this effect can be mimicked by the addition of methylobacteria to germ-free seedlings. Using five different bacterial species (Methylobacterium mesophilicum, Methylobacterium extorquens, Methylobacterium oryzae, Methylobacterium podarium, and Methylobacterium radiotolerans), we show that, over 9 days of seedling development in a light-dark cycle, root development (hair elongation, length of the primary root, branching patterns) is regulated by these epiphytic microbes that occur in the rhizosphere of field-grown plants. In a sterile liquid culture test system, auxin (IAA) inhibited root growth with little effect on hair elongation and significantly stimulated hypocotyl enlargement. Cytokinins (trans-zeatin, kinetin) and ethylene (application of the precursor ACC) likewise exerted an inhibitory effect on root growth but, in contrast to IAA, drastically stimulated root hair elongation. Methylobacteria are phytosymbionts that produce/secrete cytokinins. We conclude that, under real-world conditions (soil), the provision of these phytohormones by methylobacteria (and other epiphytic microbes) regulates root development during seedling establishment.

Comparative proteomics of leaves found at different stem positions of maize seedlings.

PubMed

Chen, Yi-Bo; Wang, Dan; Ge, Xuan-Liang; Zhao, Biligen-Gaowa; Wang, Xu-Chu; Wang, Bai-Chen

2016-07-01

To better understand the roles of leaves at different stem positions during plant development, we measured the physiological properties of leaves 1-4 on maize seedling stems, and performed a proteomics study to investigate the differences in protein expression in the four leaves using two-dimensional difference gel electrophoresis and tandem mass spectrometry in conjunction with database searching. A total of 167 significantly differentially expressed protein spots were found and identified. Of these, 35% are involved in photosynthesis. By further analysis of the data, we speculated that in leaf 1 the seedling has started to transition from a heterotroph to an autotroph, development of leaf 2 is the time at which the seedling fully transitions from a heterotroph to an autotroph, and leaf maturity was reached only with fully expanded leaves 3 and 4, although there were still some protein expression differences in the two leaves. These results suggest that the different leaves make different contributions to maize seedling growth via modulation of the expression of the photosynthetic proteins. Together, these results provide insight into the roles of the different maize leaves as the plant develops from a heterotroph to an autotroph. Copyright © 2016 Elsevier GmbH. All rights reserved.

Final Report: N-Acylethanolamine metabolism and the acquisition of photoautotrophy during seedling establishment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapman, Kent D.

Research in our labs, supported since 2005 by Basic Energy Sciences, has led to the discovery of a new lipid mediator pathway that influences phytohormone-mediated regulation of plant growth and development—the so-called N-acylethanolamine (NAE) regulatory pathway. This pathway in plants shares conserved metabolic machinery with the endocannabinoid signaling system of vertebrates that regulates a multitude of physiological and behavioral processes in mammals, suggesting that the metabolism of NAEs is an important regulatory feature of eukaryotic biology. Current evidence in plants points to interactions between NAE metabolism, abscisic acid (ABA) signaling and light signaling to modulate seedling establishment and the acquisitionmore » of photoautotrophic growth. The proposed research fits well within the mission of Photosynthetic Systems and Physical Biosciences which seek “to understand the processes by which plants, algae and non-medical microbes capture, convert and/or store energy”. The fundamental regulatory processes that govern seedling establishment directly influence the assembly of photosynthetic energy conversion systems in essentially all higher plants. Our main hypothesis is that seedlings coordinate the metabolic depletion of NAEs during seedling establishment through a complex interaction of hydrolysis (by fatty acid amide hydrolase, FAAH) and oxidation (by lipoxygenases, LOX) and that newly-reported oxylipin metabolites of polyunsaturated NAEs help to coordinate seedling development and acquisition of photoautotrophy in response to appropriate environmental cues. Evidence suggests that ethanolmide oxylipins derived from NAEs can reversibly accumulate in seedlings and adjust/arrest seedling establishment and chloroplast development in conjunction with ABA signaling and light-signaling pathways. Our results provide important new information linking the production of small molecule lipid mediators in seedlings to the coordinated development of photoautorophy. While relevant to how plants capture, convert and store energy, this work also extends to the general understanding of acylethanolamides and their bioactivity in eukaryotic organisms. In addition, analytical mass spectrometry methodology developed in this work also helped to demonstrate the identification, quantification and spatial localization of NAEs and other lipids in various plant and animal tissues. Cumulative scholarly output includes 45 publications, 2 U.S. Patents, and 24 invited research seminars. This research funding also supported the training of 2 master’s students, 4 Ph.D. students and 3 postdoctoral scholars, enhancing the human infrastructure of the U.S. science enterprise.« less

Effect of litter, leaf cover and cover of basal internodes of the dominant species Molinia caerulea on seedling recruitment and established vegetation

NASA Astrophysics Data System (ADS)

Janeček, Štěpán; Lepš, Jan

2005-09-01

The effects of litter removal, leaf cover of established plants and cover of basal internodes of a dominant species Molinia caerulea on seedling germination and the dynamics of established plants were studied in a field experiment in an oligotrophic wet meadow. Although the negative influence of litter on total seedling number and seedling species composition was non-significant, litter significantly affected the dynamics of the established vegetation and caused inhibition of total leaf cover development. The effects of total leaf cover of established plants on seedling establishment changed during the vegetation season. Whereas the effect of total leaf cover was positive at the start and in the middle of the vegetation season, at the end the total leaf cover negatively affected seedling establishment. Both total leaf cover and cover of basal internodes affected seedling composition. Effects of these two variables were statistically separable suggesting that they are based on different mechanisms. The response of seedling establishment to these factors was species specific and, consequently, our data support the hypothesis that that biotically generated spatial heterogeneity can promote species co-existence through the differentiation of species regeneration niches.

Melatonin Has the Potential to Alleviate Cinnamic Acid Stress in Cucumber Seedlings

PubMed Central

Li, Juanqi; Li, Yang; Tian, Yongqiang; Qu, Mei; Zhang, Wenna; Gao, Lihong

2017-01-01

Cinnamic acid (CA), which is a well-known major autotoxin secreted by the roots in cucumber continuous cropping, has been proven to exhibit inhibitory regulation of plant morphogenesis and development. Melatonin (MT) has been recently demonstrated to play important roles in alleviating plant abiotic stresses. To investigate whether MT supplementation could improve cucumber seedling growth under CA stress, we treated cucumber seeds and seedlings with/without MT under CA- or non-stress conditions, and then tested their effects on cucumber seedling growth, morphology, nutrient element content, and plant hormone. Overall, 10 μM MT best rescued cucumber seedling growth under 0.4 mM CA stress. MT was found to alleviate CA-stressed seedling growth by increasing the growth rates of cotyledons and leaves and by stimulating lateral root growth. Additionally, MT increased the allocation of newly gained dry weight in roots and improved the tolerance of cucumber seedlings to CA stress by altering the nutrient elements and hormone contents of the whole plant. These results strongly suggest that the application of MT can effectively improve cucumber seedling tolerance to CA stress through the perception and integration of morphology, nutrient element content and plant hormone signaling crosstalk. PMID:28751899

Genetic differentiation among populations of Pinus ponderosa from the upper Colorado River Basin

Treesearch

Gerald Rehfeldt

1990-01-01

Genetic variation among 62 populations of ponderosa pine was studied by comparing seedlings from all populations according to (1) growth and development of 4-yr-old seedlings in three disparate common gardens and (2) patterns of shoot elongation of 2-yr-old seedlings in a greenhouse. Genetic variation was detected among populations for 19 of the variables, most of...

Two Novel Techniques to Screen Abies Seedlings for Resistance to the Balsam Woolly Adelgid, Adelges piceae

PubMed Central

Newton, Leslie; Frampton, John; Monahan, John; Goldfarb, Barry; Hain, Fred

2011-01-01

Since its introduction into the Southern Appalachians in the 1950s, the balsam woolly adelgid, Adelges piceae Ratzeburg (Hemiptera: Adelgidae), has devastated native populations of Fraser fir, Abies fraseri (Pursh) Poir. (Pinales: Pinaceae), and has become a major pest in Christmas tree plantations requiring expensive chemical treatments. Adelges piceae—resistant Fraser fir trees would lessen costs for the Christmas tree industry and assist in the restoration of native stands. Resistance screening is an important step in this process. Here, four studies directed toward the development of time— and cost—efficient techniques for screening are reported. In the first study, three methods to artificially infest seedlings of different ages were evaluated in a shade—covered greenhouse. Two—year—old seedlings had much lower infestation levels than 7 year—old seedlings. Placing infested bark at the base of the seedling was less effective than tying infested bark to the seedling or suspending infested bolts above the seedling. Although the two latter techniques resulted in similar densities on the seedlings, they each have positive and negative considerations. Attaching bark to uninfested trees is effective, but very time consuming. The suspended bolt method mimics natural infestation and is more economical than attaching bark, but care must be taken to ensure an even distribution of crawlers falling onto the seedlings. The second study focused on the density and distribution of crawlers falling from suspended bolts onto paper gridded into 7.6 × 7.6 cm cells. Crawler density in a 30 cm band under and to each side of the suspended bolt ranged from 400 to over 3000 crawlers per cell (1 to 55 crawlers per cm2). In the third study, excised branches from 4 year—old A. fraseri and A. vetchii seedlings were artificially infested with A. piceae to determine whether this technique may be useful for early resistance screening. The excised A. fraseri branches supported complete adelgid development (crawler to egg—laying adult), and very little adelgid development occurred on A. vetchii branches. The fourth study compared infestation levels and gouting response on excised versus intact branches of 4 year—old A. fraseri seedlings from three different seed sources, and excised branches from 4 year—old and 25 year—old trees. There were no differences in infestation levels between excised versus intact branches nor in very young versus mature trees; gouting response was observed only on intact branches. PMID:22239164

REFORESTATION AND SEEDLING SYMBIONTS

EPA Science Inventory

Tree seedlings are dependent on symbiotic associations with microorganisms including bacteria, fungi, and actinomycetes for normal growth and development. itrogen fixing leguminous and non-leguminous trees form symbiotic relationships with Rhizobium (bacteria) and Frankia (actino...

Role of a respiratory burst oxidase of Lepidium sativum (cress) seedlings in root development and auxin signalling

PubMed Central

Müller, Kerstin; Linkies, Ada; Kermode, Allison R.

2012-01-01

Reactive oxygen species are increasingly perceived as players in plant development and plant hormone signalling pathways. One of these species, superoxide, is produced in the apoplast by respiratory burst oxidase homologues (rbohs), a family of proteins that is conserved throughout the plant kingdom. Because of the availability of mutants, the focus of research into plant rbohs has been on Arabidopsis thaliana, mainly on AtrbohD and AtrbohF. This study investigates: (i) a different member of the Atrboh family, AtrbohB, and (ii) several rbohs from the close relative of A. thaliana, Lepidium sativum (‘cress’). Five cress rbohs (Lesarbohs) were sequenced and it was found that their expression patterns were similar to their Arabidopsis orthologues throughout the life cycle. Cress plants in which LesarbohB expression was knocked down showed a strong seedling root phenotype that resembles phenotypes associated with defective auxin-related genes. These transgenic plants further displayed altered expression of auxin marker genes including those encoding the auxin responsive proteins 14 and 5 (IAA14 and IAA5), and LBD16 (LATERAL ORGAN BOUNDARIES DOMAIN16), an auxin-responsive protein implicated in lateral root initiation. It is speculated that ROS produced by rbohs play a role in root development via auxin signalling. PMID:23095998

Nucleolar structure and proliferation activity of Arabidopsis root cells from seedlings germinated on the International Space Station

NASA Astrophysics Data System (ADS)

Matía, Isabel; González-Camacho, Fernando; Marco, Roberto; Kiss, John Z.; Gasset, Gilbert; Medina, Francisco-Javier

Seeds of Arabidopsis thaliana were sent to the International Space Station in the "Cervantes Mission" (Spanish Soyuz Mission). Seed germination was initiated in flight by supplying culture medium. Seedlings were grown for 4 days at 22 °C, and growth was stopped by the addition of paraformaldehyde fixative. Once back on the ground, samples were immediately processed for microscopy. A ground control experiment was simultaneously replicated. Glutaraldehyde-fixed root cells from seedlings grown in the Biorack on board of the Space Shuttle (STS-84 Mission) in similar conditions were also ultrastructurally examined. The length of seedlings grown at 1 g was conspicuously shorter than parallel samples grown under microgravity. We examined the morphology of the root meristematic cells, with a focus on their nucleoli in the cortex and stele. In general, root cortical cells proliferate at a higher rate and their nucleoli are more active than those of stele cells. While the stele showed longer cells with larger nucleoli in the flight samples, cortical cells from space-grown seedlings were shorter, more numerous and more densely packed than ground controls. However, nucleoli were smaller and less active in fast proliferating flight cells than in the ground controls. This reduced level of ribosome synthesis in the flight samples is probably the result of an accelerated cell cycle. An altered rate of cell proliferation may be detrimental for the plant and could be the reason for the reported smaller size of older space-grown seedlings. Finally, two-dimensional protein electrophoresis showed noticeable differences between space samples and ground controls.

Seedlings of temperate rainforest conifer and angiosperm trees differ in leaf area display.

PubMed

Lusk, Christopher H; Pérez-Millaqueo, Manuel M; Saldaña, Alfredo; Burns, Bruce R; Laughlin, Daniel C; Falster, Daniel S

2012-07-01

The contemporary relegation of conifers mainly to cold or infertile sites has been ascribed to low competitive ability, as a result of the hydraulic inefficiency of tracheids and their seedlings' initial dependence on small foliage areas. Here it is hypothesized that, in temperate rainforests, the larger leaves of angiosperms also reduce self-shading and thus enable display of larger effective foliage areas than the numerous small leaves of conifers. This hypothesis was tested using 3-D modelling of plant architecture and structural equation modelling to compare self-shading and light interception potential of seedlings of six conifers and 12 angiosperm trees from temperate rainforests. The ratio of displayed leaf area to plant mass (LAR(d)) was used to indicate plant light interception potential: LAR(d) is the product of specific leaf area, leaf mass fraction, self-shading and leaf angle. Angiosperm seedlings self-shaded less than conifers, mainly because of differences in leaf number (more than leaf size), and on average their LAR(d) was about twice that of conifers. Although specific leaf area was the most pervasive influence on LAR(d), differences in self-shading also significantly influenced LAR(d) of large seedlings. The ability to deploy foliage in relatively few, large leaves is advantageous in minimizing self-shading and enhancing seedling light interception potential per unit of plant biomass. This study adds significantly to evidence that vegetative traits may be at least as important as reproductive innovations in explaining the success of angiosperms in productive environments where vegetation is structured by light competition.

Seedlings of temperate rainforest conifer and angiosperm trees differ in leaf area display

PubMed Central

Lusk, Christopher H.; Pérez-Millaqueo, Manuel M.; Saldaña, Alfredo; Burns, Bruce R.; Laughlin, Daniel C.; Falster, Daniel S.

2012-01-01

Background and Aims The contemporary relegation of conifers mainly to cold or infertile sites has been ascribed to low competitive ability, as a result of the hydraulic inefficiency of tracheids and their seedlings' initial dependence on small foliage areas. Here it is hypothesized that, in temperate rainforests, the larger leaves of angiosperms also reduce self-shading and thus enable display of larger effective foliage areas than the numerous small leaves of conifers. Methods This hypothesis was tested using 3-D modelling of plant architecture and structural equation modelling to compare self-shading and light interception potential of seedlings of six conifers and 12 angiosperm trees from temperate rainforests. The ratio of displayed leaf area to plant mass (LARd) was used to indicate plant light interception potential: LARd is the product of specific leaf area, leaf mass fraction, self-shading and leaf angle. Results Angiosperm seedlings self-shaded less than conifers, mainly because of differences in leaf number (more than leaf size), and on average their LARd was about twice that of conifers. Although specific leaf area was the most pervasive influence on LARd, differences in self-shading also significantly influenced LARd of large seedlings. Conclusions The ability to deploy foliage in relatively few, large leaves is advantageous in minimizing self-shading and enhancing seedling light interception potential per unit of plant biomass. This study adds significantly to evidence that vegetative traits may be at least as important as reproductive innovations in explaining the success of angiosperms in productive environments where vegetation is structured by light competition. PMID:22585929

Ectopic shoot meristem generation in monocotyledonous rpk1 mutants is linked to SAM loss and altered seedling morphology.

PubMed

Fiesselmann, Birgit S; Luichtl, Miriam; Yang, Xiaomeng; Matthes, Michaela; Peis, Ottilie; Torres-Ruiz, Ramon A

2015-07-07

In dicot Arabidopsis thaliana embryos two cotyledons develop largely autonomously from the shoot apical meristem (SAM). Recessive mutations in the Arabidopsis receptor-like kinase RPK1 lead to monocotyledonous seedlings, with low (10 %) penetrance due to complex functional redundancy. In strong rpk1 alleles, about 10 % of these (i. e. 1 % of all homozygotes) did not develop a SAM. We wondered whether RPK1 might also control SAM gene expression and SAM generation in addition to its known stochastic impact on cell division and PINFORMED1 (PIN1) polarity in the epidermis. SAM-less seedlings developed a simple morphology with a straight and continuous hypocotyl-cotyledon structure lacking a recognizable epicotyl. According to rpk1's auxin-related PIN1 defect, the seedlings displayed defects in the vascular tissue. Surprisingly, SAM-less seedlings variably expressed essential SAM specific genes along the hypocotyl-cotyledon structure up into the cotyledon lamina. Few were even capable of developing an ectopic shoot meristem (eSM) on top of the cotyledon. The results highlight the developmental autonomy of the SAM vs. cotyledons and suggest that the primary rpk1 defect does not lie in the seedling's ability to express SAM genes or to develop a shoot meristem. Rather, rpk1's known defects in cell division and auxin homeostasis, by disturbed PIN1 polarity, impact on SAM and organ generation. In early embryo stages this failure generates a simplified monocotyledonous morphology. Once generated, this likely entails a loss of positional information that in turn affects the spatiotemporal development of the SAM. SAM-bearing and SAM-less monocotyledonous phenotypes show morphological similarities either to real monocots or to dicot species, which only develop one cotyledon. The specific cotyledon defect in rpk1 mutants thus sheds light upon the developmental implications of the transition from two cotyledons to one.

Lead induced changes in growth and micronutrient uptake of Jatropha curcas L.

PubMed

Shu, Xiao; Zhang, QuanFa; Wang, WeiBo

2014-11-01

Effects of lead treatment on growth and micronutrient uptake in Jatropha curcas L. seedlings were assessed by means of microcosm experiments. Results suggested that superoxide dismutase (SOD) activity increased with increasing lead concentration. There was significant positive correlation between lead treatment concentration and SOD and peroxidase activity. Catalase activity was initiated under lower lead stress but, was inhibited under higher lead exposure. Lead had a stimulating effect on seedlings height and leaf area at lower lead concentrations. The J. curcas can accumulate higher amounts of available lead from soil but can translocate only low amounts to the shoots. Results indicating SOD and peroxidase activity in J. curcas seedlings played an important role in resisting the oxidative stress induced by lead. The addition of lead significantly increased the content of zinc in plant tissue and enhanced the transport of iron from roots to shoots but contributed to a decrease in measured copper, iron, and manganese content.

Elimination of toxicity from polyurethane foam plugs used for plant culture

NASA Technical Reports Server (NTRS)

Wheeler, R. M.; Schwartzkopf, S. H.; Tibbitts, T. W.; Langhans, R. W.

1985-01-01

Polyurethane foam plugs commonly are used as collars or supports to grow plants in solution culture. Despite their utility, these foam plugs can be quite toxic to plants, particularly to small seedlings. We have observed tissue injury in tests using plugs to support lettuce, red beet, and potato plants in solution culture. Typically, the injury is initiated on the hypocotyl or stem tissue in direct contact with the foam, and appears within 30 hr as a brownish discoloration on the tissue surface. This discoloration can be followed by complete collapse of affected tissue and eventual death of the seedling. When injury does not progress beyond surface browning, the seedling survives but growth is slowed. In this paper, we report on different treatments that can be used to remove the toxicity of these plugs so they can be used in plant research.

Seedling development and evaluation of genetic stability of cryopreserved Dendrobium hybrid mature seeds.

PubMed

Galdiano, Renato Fernandes; de Macedo Lemos, Eliana Gertrudes; de Faria, Ricardo Tadeu; Vendrame, Wagner Aparecido

2014-03-01

Vitrification, a simple, fast, and recommended cryopreservation method for orchid germplasm conservation, was evaluated for Dendrobium hybrid "Dong Yai" mature seeds. The genetic stability of regenerated seedlings was also evaluated using flow cytometry. Mature seeds from this hybrid were submitted to plant vitrification solution (PVS2) for 0, 0.5, 1, 2, 3, 4, 5, or 6 h at 0 °C. Subsequently, they were plunged into liquid nitrogen (LN) at -196 °C for 1 h and recovered in half-strength Murashige and Skoog culture medium (1/2 MS), and seed germination was evaluated after 30 days. Seeds directly submitted to LN did not germinate after cryopreservation. Seeds treated with PVS2 between 1 and 3 h presented the best germination (between 51 and 58%), although longer exposure to PVS2 returned moderated germination (39%). Germinated seeds were further subcultured in P-723 culture medium and developed whole seedlings in vitro after 180 days, with no abnormal characteristics, diseases, or nutritional deficiencies. Seedlings were successfully acclimatized under greenhouse conditions with over 80% survival. Flow cytometry analysis revealed no chromosomal changes on vitrified seedlings, as well as seedlings germinated from the control treatment (direct exposure to LN). These findings indicate that vitrification is a feasible and safe germplasm cryopreservation method for commercial Dendrobium orchid hybrid conservation.

Hydrogen sulphide improves adaptation of Zea mays seedlings to iron deficiency

PubMed Central

Chen, Juan; Wu, Fei-Hua; Shang, Yu-Ting; Wang, Wen-Hua; Hu, Wen-Jun; Simon, Martin; Liu, Xiang; Shangguan, Zhou-Ping; Zheng, Hai-Lei

2015-01-01

Hydrogen sulphide (H2S) is emerging as a potential molecule involved in physiological regulation in plants. However, whether H2S regulates iron-shortage responses in plants is largely unknown. Here, the role of H2S in modulating iron availability in maize (Zea mays L. cv Canner) seedlings grown in iron-deficient culture solution is reported. The main results are as follows: Firstly, NaHS, a donor of H2S, completely prevented leaf interveinal chlorosis in maize seedlings grown in iron-deficient culture solution. Secondly, electron micrographs of mesophyll cells from iron-deficient maize seedlings revealed plastids with few photosynthetic lamellae and rudimentary grana. On the contrary, mesophyll chloroplasts appeared completely developed in H2S-treated maize seedlings. Thirdly, H2S treatment increased iron accumulation in maize seedlings by changing the expression levels of iron homeostasis- and sulphur metabolism-related genes. Fourthly, phytosiderophore (PS) accumulation and secretion were enhanced by H2S treatment in seedlings grown in iron-deficient solution. Indeed, the gene expression of ferric-phytosiderophore transporter (ZmYS1) was specifically induced by iron deficiency in maize leaves and roots, whereas their abundance was decreased by NaHS treatment. Lastly, H2S significantly enhanced photosynthesis through promoting the protein expression of ribulose-1,5-bisphosphate carboxylase large subunit (RuBISCO LSU) and phosphoenolpyruvate carboxylase (PEPC) and the expression of genes encoding RuBISCO large subunit (RBCL), small subunit (RBCS), D1 protein (psbA), and PEPC in maize seedlings grown in iron-deficient solution. These results indicate that H2S is closely related to iron uptake, transport, and accumulation, and consequently increases chlorophyll biosynthesis, chloroplast development, and photosynthesis in plants. PMID:26208645

Hydrogen sulphide improves adaptation of Zea mays seedlings to iron deficiency.

PubMed

Chen, Juan; Wu, Fei-Hua; Shang, Yu-Ting; Wang, Wen-Hua; Hu, Wen-Jun; Simon, Martin; Liu, Xiang; Shangguan, Zhou-Ping; Zheng, Hai-Lei

2015-11-01

Hydrogen sulphide (H2S) is emerging as a potential molecule involved in physiological regulation in plants. However, whether H2S regulates iron-shortage responses in plants is largely unknown. Here, the role of H2S in modulating iron availability in maize (Zea mays L. cv Canner) seedlings grown in iron-deficient culture solution is reported. The main results are as follows: Firstly, NaHS, a donor of H2S, completely prevented leaf interveinal chlorosis in maize seedlings grown in iron-deficient culture solution. Secondly, electron micrographs of mesophyll cells from iron-deficient maize seedlings revealed plastids with few photosynthetic lamellae and rudimentary grana. On the contrary, mesophyll chloroplasts appeared completely developed in H2S-treated maize seedlings. Thirdly, H2S treatment increased iron accumulation in maize seedlings by changing the expression levels of iron homeostasis- and sulphur metabolism-related genes. Fourthly, phytosiderophore (PS) accumulation and secretion were enhanced by H2S treatment in seedlings grown in iron-deficient solution. Indeed, the gene expression of ferric-phytosiderophore transporter (ZmYS1) was specifically induced by iron deficiency in maize leaves and roots, whereas their abundance was decreased by NaHS treatment. Lastly, H2S significantly enhanced photosynthesis through promoting the protein expression of ribulose-1,5-bisphosphate carboxylase large subunit (RuBISCO LSU) and phosphoenolpyruvate carboxylase (PEPC) and the expression of genes encoding RuBISCO large subunit (RBCL), small subunit (RBCS), D1 protein (psbA), and PEPC in maize seedlings grown in iron-deficient solution. These results indicate that H2S is closely related to iron uptake, transport, and accumulation, and consequently increases chlorophyll biosynthesis, chloroplast development, and photosynthesis in plants. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Release of suppressed oak advance regeneration

Treesearch

Dylan Dillaway; Jeffrey W. Stringer

2006-01-01

Oaks are not consistently regenerating on intermediate- and high-quality sites due to the lack of well-developed advance regeneration. Studies of northern red oak (Quercus rubra L.) seedling cohorts have shown that when grown under well-developed canopies and mid-stories, height growth is suppressed, and seedling mortality increases with time resulting in a sparsely...

Shading reduces growth of longleaf and loblolly pine seedlings in containers

Treesearch

James P. Barnett

1989-01-01

Development of longleaf (Pinus palustris Mill.) and loblolly (P. taeda L.) pine seediings growing under three light conditions--full sunlight, 30% shade, and 50% shade--was evaluated. Although there was little difference between development of seedlings in 30% and 50% shade, those grown is full sunlight were signiticantly larger...

Formation and early development of tetraspores of Polysiphonia urceolata (Rhodomelaceae, Rhodophyta)

NASA Astrophysics Data System (ADS)

Yao, Jianting; Li, Dapeng; Yu, Shenhui; Liu, Jidong; Duan, Delin

2009-05-01

Polysiphonia urceolata is one type of potential commercial red seaweeds used for breeding and cultivation, because of its significant biochemical and biomedical application. However, the information of breeding and seedling incubation for cultivation is limited, especially the early development. In this study, tetrasporohyte and gametophyte of P. urceolata were taken as the study materials in Huiquan Bay, Qingdao, China. The cleaned and sterilized tetrasporophytes and gametophytes were pre-cultured in sterilized seawater, then nurtured at 18°C, 25 μmol photons m-2 s-1 in 12:12 h (light:dark) photoperiod. Continuous observation under microscope showed that the early development consists of bipolar division stage and seedling stage. In the division stage, tetraspores germinate into bipolar sporelings that further differentiate into a colorless rhizoidal portion and a lightly pigmented upright shoot. The lightly pigmented rhizoidal cell develops to a rhizoid and the larger pigmented cell transforms to an erect axis. In the seedling stage, several quasi-protuberances appear on the erect axis and form juvenile seedlings. The results demonstrate the culture of P. urceolata from tetraspores under laboratory conditions.

Phylogenetic Structure of Tree Species across Different Life Stages from Seedlings to Canopy Trees in a Subtropical Evergreen Broad-Leaved Forest.

PubMed

Jin, Yi; Qian, Hong; Yu, Mingjian

2015-01-01

Investigating patterns of phylogenetic structure across different life stages of tree species in forests is crucial to understanding forest community assembly, and investigating forest gap influence on the phylogenetic structure of forest regeneration is necessary for understanding forest community assembly. Here, we examine the phylogenetic structure of tree species across life stages from seedlings to canopy trees, as well as forest gap influence on the phylogenetic structure of forest regeneration in a forest of the subtropical region in China. We investigate changes in phylogenetic relatedness (measured as NRI) of tree species from seedlings, saplings, treelets to canopy trees; we compare the phylogenetic turnover (measured as βNRI) between canopy trees and seedlings in forest understory with that between canopy trees and seedlings in forest gaps. We found that phylogenetic relatedness generally increases from seedlings through saplings and treelets up to canopy trees, and that phylogenetic relatedness does not differ between seedlings in forest understory and those in forest gaps, but phylogenetic turnover between canopy trees and seedlings in forest understory is lower than that between canopy trees and seedlings in forest gaps. We conclude that tree species tend to be more closely related from seedling to canopy layers, and that forest gaps alter the seedling phylogenetic turnover of the studied forest. It is likely that the increasing trend of phylogenetic clustering as tree stem size increases observed in this subtropical forest is primarily driven by abiotic filtering processes, which select a set of closely related evergreen broad-leaved tree species whose regeneration has adapted to the closed canopy environments of the subtropical forest developed under the regional monsoon climate.

Phylogenetic Structure of Tree Species across Different Life Stages from Seedlings to Canopy Trees in a Subtropical Evergreen Broad-Leaved Forest

PubMed Central

Jin, Yi; Qian, Hong; Yu, Mingjian

2015-01-01

Investigating patterns of phylogenetic structure across different life stages of tree species in forests is crucial to understanding forest community assembly, and investigating forest gap influence on the phylogenetic structure of forest regeneration is necessary for understanding forest community assembly. Here, we examine the phylogenetic structure of tree species across life stages from seedlings to canopy trees, as well as forest gap influence on the phylogenetic structure of forest regeneration in a forest of the subtropical region in China. We investigate changes in phylogenetic relatedness (measured as NRI) of tree species from seedlings, saplings, treelets to canopy trees; we compare the phylogenetic turnover (measured as βNRI) between canopy trees and seedlings in forest understory with that between canopy trees and seedlings in forest gaps. We found that phylogenetic relatedness generally increases from seedlings through saplings and treelets up to canopy trees, and that phylogenetic relatedness does not differ between seedlings in forest understory and those in forest gaps, but phylogenetic turnover between canopy trees and seedlings in forest understory is lower than that between canopy trees and seedlings in forest gaps. We conclude that tree species tend to be more closely related from seedling to canopy layers, and that forest gaps alter the seedling phylogenetic turnover of the studied forest. It is likely that the increasing trend of phylogenetic clustering as tree stem size increases observed in this subtropical forest is primarily driven by abiotic filtering processes, which select a set of closely related evergreen broad-leaved tree species whose regeneration has adapted to the closed canopy environments of the subtropical forest developed under the regional monsoon climate. PMID:26098916

Variability in CitXET expression and XET activity in Citrus cultivar Huangguogan seedlings with differed degrees of etiolation

PubMed Central

Xiong, Bo; Gu, Xianjie; Qiu, Xia; Dong, Zhixiang; Ye, Shuang; Sun, Guochao; Huang, Shengjia; Liu, Xinya; Xi, Lijuan

2017-01-01

Considering the known effects of xyloglucan endotransglycosylase (XET) on plant growth and development, we aimed to determine whether XETs help to regulate the growth and elongation of Huangguogan shoots and roots. We confirmed a possible role for XET during seedling etiolation. Our results revealed that the roots of etiolated seedlings (H-E) were longer than those of green seedlings (H-G). However, shoot length exhibited the opposite pattern. We also observed positive and negative effects on the xyloglucan-degrading activity of XET in the root sub-apical region and shoots of etiolated Huangguogan seedling, respectively. There was a significant down-regulation in CitXET expression in the etiolated shoots at 15 days after seed germination. On the contrary, it was significantly increased in the root sub-apical region of etiolated and multicolored seedlings at 15 days after seed germination. The XET coding sequence (i.e., CitXET) was cloned from Huangguogan seedlings using gene-specific primers. The encoded amino acid sequence was predicted by using bioinformatics-based methods. The 990-bp CitXET gene was highly homologous to other XET genes. The CitXET protein was predicted to contain 319 amino acids, with a molecular mass of 37.45 kDa and an isoelectric point of 9.05. The predicted molecular formula was C1724H2548N448O466S14, and the resulting protein included only one transmembrane structure. The CitXET secondary structure consisted of four main structures (i.e., 21% α-helix, 30.72% extended strand, 9.09% β-turn, and 39.18% random coil). Analyses involving the NCBI Conserved Domains Database (NCBI-CDD), InterPro, and ScanProsite revealed that CitXET was a member of the glycosyl hydrolase family 16 (GH16), and included the DEIDFEFLG motif. Our results indicate that the differed degrees of etiolation influenced the CitXET expression pattern and XET activity in Huangguogan seedlings. The differential changes in XET activity and CitXET expression levels in Huangguogan seedlings may influence the regulation of root and shoot development, and may be important for seedling etiolation. PMID:28617857

CPK3-phosphorylated RhoGDI1 is essential in the development of Arabidopsis seedlings and leaf epidermal cells

PubMed Central

Wu, Yan

2013-01-01

The regulation of Rho of plants (ROP) in morphogenesis of leaf epidermal cells has been well studied, but the roles concerning regulators of ROPs such as RhoGDIs are poorly understood. This study reports that AtRhoGDI1 (GDI1) acts as a versatile regulator to modulate development of seedlings and leaf pavement cells. In mutant gdi1, leaf pavement cells showed shorter lobes in comparison with those in wild type. In GDI1-14 seedlings (GDI1-overexpression line) the growth of lobes in pavement cells was severely suppressed and the development of seedlings was altered. These results indicate that GDI1 plays an essential role in morphogenesis of epidermal pavement cells through modulating the ROP signalling pathways. The interaction between GDI1 and ROP2 or ROP6 was detected in the leaf pavement cells using FRET analysis. Dominant negative, not constitutively active, DN-rop6 could weaken the effect caused by overexpression of GDI1; because the pleiotropic phenotype of GDI1-14 plants was eliminated in the hybrid line GDI1-14 DN-rop6. GDI1 could be phosphorylated by CPK3. Three conserved Ser/Thr residues in GDI1 were determined as targeted amino acids for CPK3. Overexpression of GDI1(3D), not GDI1(3A), could rescue the abnormal growth phenotypes of gdi1-1 seedlings, demonstrating the impact of GDI1 phosphorylation in the development of Arabidopsis. In summary, these results suggest that GDI1 regulation in morphogenesis of seedlings and leaf pavement cells could be undergone through modulating the ROP signalling pathways and the phosphorylation of GDI1 by CPK3 was required for the developmental modulation in Arabidopsis. PMID:23846874

Genetically improved ponderosa pine seedlings outgrow nursery-run seedlings with and without competition -- Early findings

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDonald, P.M.; Fiddler, G.O.; Kitzmiller, J.H.

1994-04-01

Three classes of ponderosa pine (Pinus ponderosa) seedlings (nursery-run, wind-pollinated, control-pollinated) were evaluated for stem height and diameter at the USDA Forest Service's Placerville Nursery and the Georgetown Range District in northern California. Pines in all three classes were grown with competing vegetation or maintained in a free-to-grow condition. Control-pollinated seedlings were statistically taller than nursery-run counterparts when outplanted, and after 1 and 2 growing seasons in the field with and without competition. They also had significantly larger diameters when outplanted and after 2 growing seasons in the field when free to grow. Wind-pollinated seedlings grew taller than nursery-run seedlingsmore » when free to grow. A large amount of competing vegetation [bearclover (Chamaebatia foliolosa)--29,490 plants per acre; herbaceous vegetation--11,500; hardwood sprouts--233; and whiteleaf manzanita (Arctostaphylos viscida) seedlings--100] ensure that future pine development will be tested rigorously.« less

Involvement of an antioxidant defense system in the adaptive response to cadmium in maize seedlings (Zea mays L.).

PubMed

Xu, Xianghua; Liu, Cuiying; Zhao, Xiaoyan; Li, Renying; Deng, Wenjing

2014-11-01

Chemical and biological analyses were used to investigate the growth response and antioxidant defense mechanism of maize seedlings (Zea mays L.) grown in soils with 0-100 mg kg(-1) Cd. Results showed that maize seedlings have strong abilities to accumulate and tolerate high concentrations of Cd. For soil with 50 mg kg(-1) Cd, the Cd contents in roots and shoots of maize seedlings are as large as 295.6 and 153.0 mg kg(-1) DW, respectively, without visible symptoms of toxicity. Lower soil Cd concentrations lead to a decrease in reduced glutathione (GSH) content in leaves of maize seedlings, whereas higher soil Cd concentrations resulted in an increase in the activities of superoxide dismutase, guaiacol peroxidase, catalase, and ascorbate peroxidase. Maize seedlings have strong capacities to adapt to low concentrations of Cd by consuming GSH and to develop an antioxidative enzyme system to defend against high-Cd stress.

Loss of desiccation tolerance in Copaifera langsdorffii Desf. seeds during germination.

PubMed

Pereira, W V S; Faria, J M R; Tonetti, O A O; Silva, E A A

2014-05-01

This study evaluated the loss of desiccation tolerance in C. langsdorffii seeds during the germination process. Seeds were imbibed for 24, 48, 72, 96, 120 and 144 hours and dried to the initial moisture content, kept in this state for 3 days after which they were submitted to pre-humidification and rehydration. Ultraestructural evaluations were done aiming to observe the cell damage caused by the dry process. Desiccation tolerance was evaluated in terms of the percentage of normal seedlings. Seeds not submitted to the drying process presented 61% of normal seedlings, and after 24 hours of imbibition, followed by drying, the seeds presented the same percentage of survival. However, after 48 hours of imbibition, seeds started to lose the desiccation tolerance. There was twenty six percent of normal seedlings formed from seeds imbibed for 96 hours and later dried and rehydrated. Only 5% of seeds imbibed for 144 hours, dried and rehydrated formed normal seedlings. At 144 hours of imbibition followed the dry process, there was damage into the cell structure, indicating that the seeds were unable to keep the cell structure during the drying process. Copaifera langsdorffii seeds loses the desiccation tolerance at the start of Phase 2 of imbibition.

Effect of Seedling Size and First-Order-Lateral Roots on Early Development of Northern Red Oak on Mesic Sites

Treesearch

Paul P. Kormanik; Shi-Jean S. Sung; Donald J. Kass; Scott Schlarbaum

1997-01-01

Northern red oak (Quercus rubra) seedlings were placed in three grades based on number of first-order-lateral roots. The grades were poor, medium, and good and had numbers of 0 to 6, 7 to 11, 12, and > 12, respectively. Eighty seedlings from each group were either underplanted or established in an adjacent clearcut on a high-quality mesic site in...

Morphology, gas exchange, and chlorophyll content of longleaf pine seedlings in response to rooting volume, copper root pruning, and nitrogen supply in a container nursery

Treesearch

R. Kasten Dumroese; Shi-Jean Susana Sung; Jeremiah R. Pinto; Amy Ross-Davis; D. Andrew Scott

2013-01-01

Few pine species develop a seedling grass stage; this growth phase, characterized by strong, carrot-like taproots and a stem-less nature, poses unique challenges during nursery production. Fertilization levels beyond optimum could result in excessive diameter growth that reduces seedling quality as measured by the root bound index (RBI). We grew longleaf pine (Pinus...

Precommercial thinning intensity in longleaf pine: effect on product volume and value

Treesearch

John S. Kush; William D. Boyer; Ralph S. Meldahl; George A. Ward

1998-01-01

The possible benefit of precommercial thinning in longleaf pine was evaluated from a spacing study initiated in 1967 on the Escambia Experimental Forest in Brewton, AL. The study was established in dense, naturally established, seedling stands 9 years from seed. Plots were thinned to densities of 300, 600, 900, 1200, and 1500 trees/acre. Later, the initial range of...

Using common mycorrhizal networks for controlled inoculation of Quercus spp. with Tuber melanosporum: the nurse plant method.

PubMed

Pereira, Guillermo; Palfner, Götz; Chávez, Daniel; Suz, Laura M; Machuca, Angela; Honrubia, Mario

2013-07-01

The high cost and restricted availability of black truffle spore inoculum for controlled mycorrhiza formation of host trees produced for truffle orchards worldwide encourage the search for more efficient and sustainable inoculation methods that can be applied globally. In this study, we evaluated the potential of the nurse plant method for the controlled inoculation of Quercus cerris and Quercus robur with Tuber melanosporum by mycorrhizal networks in pot cultures. Pine bark compost, adjusted to pH 7.8 by liming, was used as substrate for all assays. Initially, Q. robur seedlings were inoculated with truffle spores and cultured for 12 months. After this period, the plants presenting 74 % mycorrhizal fine roots were transferred to larger containers. Nurse plants were used for two treatments of two different nursling species: five sterilized acorns or five 45-day-old, axenically grown Q. robur or Q. cerris seedlings, planted in containers around the nurse plant. After 6 months, colonized nursling plant root tips showed that mycorrhiza formation by T. melanosporum was higher than 45 % in the seedlings tested, with the most successful nursling combination being Q. cerris seedlings, reaching 81 % colonization. Bulk identification of T. melanosporum mycorrhizae was based on morphological and anatomical features and confirmed by sequencing of the internal transcribed spacer region of the ribosomal DNA of selected root tips. Our results show that the nurse plant method yields attractive rates of mycorrhiza formation by the Périgord black truffle and suggest that establishing and maintaining common mycorrhizal networks in pot cultures enables sustained use of the initial spore inoculum.

Following isotopes in pulse-chase enriched aspen seedlings

NASA Astrophysics Data System (ADS)

Norris, C. E.; Wasylishen, R. E.; Landhäusser, S.; Quideau, S. A.

2011-12-01

One method to quantitatively trace biogeochemical fluxes through ecosystems, such as organic matter decomposition, is to use plant material enriched with stable isotopes. However, as plant macromolecules are known to vary in their rate of formation and decomposition, both the enrichment levels and the location of enrichment within the plant material should be characterized prior to decomposition and tracing studies. Aspen (Populus tremuloides Michx.) is a common tree species with a diverse organic matter chemical structure found in the western Canadian boreal forest. This study used a multi pulse and multi chase enrichment of stable isotopes (15N and 13C) on aspen seedlings to determine the seedling enrichment, isotope movement among plant tissues and translocation of isotopes within plant macromolecules e.g., carbohydrates and lignin. As expected, all tissues experienced increased enrichment with multiple pulses. An initial enrichment with 13C was observed in the leaves followed by translocation to the stems and roots while the 15N moved upward from the roots to leaves. The macromolecular chemistry of the organic carbon was further characterized using 13C solid state nuclear magnetic resonance spectroscopy. After the initial two hour chase period enrichment of the O-alkyl type (carbohydrate) carbon within the leaves was identified, followed by redistribution to more complex carbon compounds after the one week chase period. Root and stem tissues did not show the same pattern. Rather, changes in 13C enrichment were observed in shifting ethyl and methyl alkyl (lipid) carbon peak intensities for the stem samples while roots did not preferentially allocate 13C to a specific macromolecule. These results confirm that stable isotope enrichment of plants was non-uniform across macromolecules and tissue types. Enrichment of aspen seedlings was therefore dependant on the pulse-chase sequence used.

Isolation of cucumber CsARF cDNAs and expression of the corresponding mRNAs during gravity-regulated morphogenesis of cucumber seedlings

NASA Astrophysics Data System (ADS)

Saito, Y.; Yamasaki, S.; Fujii, N.; Hagen, G.; Guilfoyle, T.; Takahashi, H.

Cucumber seedlings grown in a horizontal position develop a protuberance called peg on the lower side of the transition zone between the hypocotyl and the root. We have suggested that peg formation on the upper side of the gravistimulated transition zone is suppressed because cucumber seedlings grown in a vertical position or microgravity symmetrically develop two pegs on the transition zone. Plant hormone, auxin, is considered to play a crucial role in the gravity-regulated formation of peg. We have shown that the mRNAs of auxin-inducible genes (CsIAAs) isolated from cucumber accumulate more abundantly in the lower side of the transition zone than in the upper side when peg formation initiates. To reveal the mechanism of transcriptional regulation by auxin for peg formation, we isolated five cDNAs of Auxin Response Factors (ARFs) from cucumber and compared their mRNA accumulation with those of CsIAA1 and CsIAA2. The tissue specificity of mRNA accumulation of CsARF2 was similar to those of CsIAA1 and CsIAA2. The structural character of CsARF2 predicts it is transcriptional activator. These results suggest that CsARF2 may be involved in activation of the transcription of auxin-inducible genes including CsIAA1 for peg formation. Because mRNA accumulation of five CsARFs, including CsARF2, were affected by neither gravity nor auxin, transcriptional activity of CsARF2 may be regulated at post-transcriptional level to induce asymmetric mRNA accumulation of auxin-inducible genes in the transition zone.

[Regeneration characteristics of woody plant seedlings in typical secondary forests in Qinling Mountains].

PubMed

Kang, Bing; Liu, Shi-Rong; Wang, De-Xiang; Zhang, Ying; Liu, Hong-Ru; Du, Yan-Ling

2011-12-01

By using sampling plot method, an investigation was conducted on the regeneration characteristics of woody plant seedlings in five kinds of typical secondary forests (Pinus tabulaeformis, Quercus valiena var. acuteserrata, Betula albo-sinensis, Picea asperata, and Pinus armandii) in Qinling Mountains. There was an obvious species differentiation of woody plant seedlings and saplings in the forests. Except for Q. valiena var. acuteserrata and P. armandii forests, the similarity coefficient of the seedlings and saplings species in the forests was lower. The seedlings and saplings quantity, species richness index, Simpson dominance index, and evenness index were higher in P. tabulaeformis and Q. valiena var. acuteserrata forests, the lowest in B. albo-sinensis forest, and basically the same in P. asperata and P. armandii forests. The percentages of the seedlings and saplings in the five forests had significant differences (P < 0.05). Except in B. albo-sinensis forest where the percentage of the saplings was higher, the percentage of the seedlings in the other stands was larger, and in the order of P. asperata forest > P. tabulaeformis forest > Q. valiena var. acuteserrata forest > P. armandii forest, respectively. The sprouting percentage of the seedlings in different forests had significant difference (P < 0.05), and was in the sequence of P. armandii forest > P. asperata forest > B. albo-sinensis forest > Q. valiena var. acuteserrata forest > P. tabulaeformis forest. In Q. valiena var. acuteserrata and P. tabulaeformis forests, the percentage of tree seedlings was the highest, occupying 68% and 51.4% of the total number of woody seedlings, respectively, and their communities were in the medium succession period, with a stronger persistent regeneration capability; in P. asperata and P. armandii forests, the percentage of tree seedlings was 40% and 15%, respectively, and their communities were in the late succession period, with a rather poor regeneration capability; while in B. albo-sinensis forest, the seedlings were difficult to develop into saplings, and thus, its continuous persistent regeneration capability was lack.

Growth and development of plants flown on the STS-3 space shuttle mission

NASA Astrophysics Data System (ADS)

Cowles, J. R.; Scheld, H. W.; Peterson, C.; LeMay, R.

Pre-germinated pine seedlings and germinating oat and mung bean seeds were flown on the STS-3 Space Shuttle mission. Overall, the seedlings grew and developed well in space. Some oat and mung bean roots, however, grew upward. Lignin content was slightly lower in flight tissues and protein content was higher.

Expected genetic gains and development plans for two longlead pine third-generation seedling seed orchards

Treesearch

C.D. Nelson; L.H. Lott; D.P. Gwaze

2005-01-01

Selection and thinning plans were developed for two longleaf pine (Pinus palushis Mill .), third-generation seedling seed orchards located in southeastern Mississippi and central Louisiana. The two orchards were part of several long-term experimental field tests designed to investigate genetic variation in height growth and brown spot needle blight (...

Leaf area and net photosynthesis during development of Prunus serotina seedlings

Treesearch

Stephen B. Horsley; Kurt W. Gottschalk

1993-01-01

We used the plastochron index to study the relationship between plant age, leaf age and development, and net photosynthesis of black cherry (Prtmus serotina Ehrh.) seedlings. Leaf area and net photosynthesis were measured on all leaves >=75 mm of plants ranging in age from 7 to 20 plastochrons. Effects of plant developmental stage...

Development of Phytophthora ramorum infection and disease symptoms on coast redwood seedlings

Treesearch

Sunny Lucas; Jennifer L. Parke; Yana Valachovic

2008-01-01

Coast redwood (Sequoia sempervirens) is a host for Phytophthora ramorum but it is not clear if the pathogen represents a significant disease risk to this tree species. In an on-going field experiment, we are examining the process of infection and the development of symptoms on coast edwood seedlings in naturally infested sites in...

Effect of acorn size on development of northern red oak 1-0 seedlings

Treesearch

Paul P. Kormanik; Shi-Jean S. Sung; T.L. Kormanik; S.E. Schlarbaum; Stanley J. Zarnoch

1998-01-01

The effect of acorn size on seedling development was determined for 20 northern red oak (Quercus rubra L.) mother tree selections from the USDA Forest Service's Eastern Tennessee Watauga seed orchard. Acorns from each mother tree were visually separated into three size groups, weighed, and sown separately in forest nurseries located in Georgia,...

Seed treatments enhance photosynthesis in maize seedlings by reducing infection with Fusarium spp. and consequent disease development in maize

USDA-ARS?s Scientific Manuscript database

The effects of a seed treatment on early season growth, seedling disease development, incidence Fusarium spp. infection, and photosynthetic performance of maize were evaluated at two locations in Iowa in 2007. Maize seed was either treated with Cruiser 2Extreme 250 ® (fludioxonil + azoxystrobin + me...

Prevalence and development of disease on coast redwood seedlings caused by Phytophthora ramorum

Treesearch

S. Lucas; J. Parke; Y. Valachovic

2009-01-01

Coast redwood (Sequoia sempervirens) is a host for Phytophthora ramorum but it is unclear if the pathogen represents a significant disease risk to this tree species. In an on-going field experiment, we are examining the prevalence of infection and the development of symptoms on coast redwood seedlings in naturally infested...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Franco, A.C.; Nobel, P.S.

Seedlings of the succulent crassulacean acid metabolism (CAM) plant Agave deserti in the northwestern Sonoran Desert were found only in sheltered microhabitats, nearly all occurring under the canopy of a desert bunchgrass, Hilaria rigida. Apparently because soil surface temperatures can reach 71{degree}C in exposed areas, seedlings were generally located near the center or on the northern side of this nurse plant. Both species have shallow root systems, about half of the roots of H. rigida and all those for seedlings of A. deserti occurring above soil depths of 0.08 m. To examine competition for water between the nurse plant andmore » an associated seedling, a three-dimensional model for root water uptake was developed. Predicted pre-dawn soil water potentials at the mean root depth and total shoot transpiration agreed well with field measurements. Simulated annual water uptake by a seedling of A. deserti was reduced {approx}50% when the seedling was moved from an exposed location to the center of the nurse plant. Shading by the nurse plant reduced total daily photosynthetically active radiation (PAR) by up to 74% compared with an exposed seedling. On the other hand, soil nitrogen under the canopy of H rigida was 60% higher than in exposed locations. Assuming that the effects of nitrogen, temperature, PAR, and soil water on net CO{sub 2} uptake are multiplicative, the predicted net CO{sub 2} uptake by a seedling of A. deserti under the nurse plant was only {approx}45% of that for an exposed seedling.« less

Effects of NaCl stress on seed germination and seedling development of Brassica insularis Moris (Brassicaceae).

PubMed

Santo, A; Mattana, E; Frigau, L; Marzo Pastor, A; Picher Morelló, M C; Bacchetta, G

2017-05-01

Brassica insularis is a protected plant that grows on both coastal and inland cliffs in the western Mediterranean Basin. The objective of this study was to test if any variability exists in the salt stress response during seed germination and seedling development in this species relative to its provenance habitat. Variability among three populations in the salt stress effects on seed germination and recovery under different temperatures was evaluated. The effect of nebulisation of a salt solution on seedling development was evaluated between populations growing at different distances from the sea. Seeds of B. insularis could germinate at NaCl concentrations up to 200 mm. Seed viability was negatively affected by salt, and recovery ability decreased with increasing temperature or salinity. Inter-population variability was detected in salt response during the seed germination phase, as well as in seedling salt spray tolerance. The inland population seedlings had drastically decreased survival and life span and failed to survive to the end of the experiment. In contrast, at least 90% of the coastal seedlings survived, even when sprayed at the highest frequency with salt solution. This study allowed investigation of two natural factors, soil salinity and marine aerosols, widely present in the B. insularis habitat, and provided the first insights into ecology of this protected species and its distribution in the Mediterranean. These results might be useful in understanding the actual distributions of other species with the same ecology that experience these same abiotic parameters. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.

A novel VIGS method by agroinoculation of cotton seeds and application for elucidating functions of GhBI-1 in salt-stress response.

PubMed

Zhang, Jingxia; Wang, Furong; Zhang, Chuanyun; Zhang, Junhao; Chen, Yu; Liu, Guodong; Zhao, Yanxiu; Hao, Fushun; Zhang, Jun

2018-06-04

A VIGS method by agroinoculation of cotton seeds was developed for gene silencing in young seedlings and roots, and applied in functional analysis of GhBI-1 in response to salt stress. Virus-induced gene silencing (VIGS) has been widely used to investigate the functions of genes expressed in mature leaves, but not yet in young seedlings or roots of cotton (Gossypium hirsutum L.). Here, we developed a simple and effective VIGS method for silencing genes in young cotton seedlings and roots by soaking naked seeds in Agrobacterium cultures carrying tobacco rattle virus (TRV)-VIGS vectors. When the naked seeds were soaked in Agrobacterium cultures with an OD600 of 1.5 for 90 min, it was optimal for silencing genes effectively in young seedlings as clear photo-bleaching phenotype in the newly emerging leaves of pTRV:GhCLA1 seedlings were observed at 12-14 days post inoculation. Silencing of GhPGF (cotton pigment gland formation) by this method resulted in a 90% decrease in transcript abundances of the gene in roots at the early development stage. We further used the tool to investigate function of GhBI-1 (cotton Bax inhibitor-1) gene in response to salt stress and demonstrated that GhBI-1 might play a protective role under salt stress by suppressing stress-induced cell death in cotton. Our results showed that the newly established VIGS method is a powerful tool for elucidating functions of genes in cotton, especially the genes expressed in young seedlings and roots.

Studies on the methods of identification of irradiated food I. Seedling growth test

NASA Astrophysics Data System (ADS)

Qiongying, Liu; Yanhua, Kuang; Yuemei, Zheng

1993-07-01

A seedling growth test for the identification of gamma irradiated edible vegetable seeds was described. The identification of gamma irradiated grape and the other seeds has been investigated. The purpose of this study was to develop an easy, rapid and practical technique for the identification of irradiated edible vegetable seeds. Seven different irradiated edible vegetable seeds as: rice ( Oryza sativa), peanut ( Arachis hypogaea), maize ( Zeamays), soybean ( Glycine max), red bean ( Phaseolus angularis), mung bean ( Phaseolus aureus) and catjang cowpea ( Vigna cylindrica) were tested by using the method of seedling growth. All of the edible vegetable seeds were exposed to gamma radiation on different doses, O(CK), 0.5, 1.0, 1.5, 2.0, 3.0, 5.0 kGy. After treatment with above 1.0 kGy dose to the seeds, the seedling rate was less than 50% compared with the control. Although the seedling rate of rice seeds can reached 58%, the seedling growth was not normal and the seedling leaves appeared deformed. The results by this method were helpful to identify gamma treatment of the edible vegetable seeds with above 1.0 kGy dose.

P-chlorophenoxyisobutyric acid impairs auxin response for gravity-regulated peg formation in cucumber (Cucumis sativus) seedlings.

PubMed

Shimizu, Minobu; Miyazawa, Yutaka; Fujii, Nobuharu; Takahashi, Hideyuki

2008-01-01

Cucumber (Cucumis sativus L.) seedlings form a specialized protuberance, the peg, on the transition zone between the hypocotyl and the root. When cucumber seeds germinate in a horizontal position, the seedlings develop a peg on the lower side of the transition zone. To verify the role of auxin action in peg formation, we examined the effect of the anti-auxin, p-chlorophenoxyisobutyric acid (PCIB), on peg formation and mRNA accumulation of auxin-regulated genes. Application of PCIB to cucumber seedlings inhibited peg formation. The application of indole-3-acetic acid (IAA) competed with PCIB and induced peg formation. Furthermore, application of PCIB decreased auxin-inducible CsIAA1 mRNA and increased auxin-repressible CsGRP1 mRNA in the lower side of the transition zone. The differential accumulation of CsIAA1 and CsGRP1 mRNAs in the transition zone of cucumber seedlings grown in a horizontal position was smaller in the PCIB-treated seedlings. These results demonstrate that endogenous auxin redistributes and induces the differential expression of auxin-regulated genes, and ultimately results in the suppression or induction of peg formation in the gravistimulated transition zone of cucumber seedlings.

Growth and mitochondrial respiration of mungbeans (Phaseolus aureus Roxb.) germinated at low pressure

NASA Technical Reports Server (NTRS)

Musgrave, M. E.; Gerth, W. A.; Scheld, H. W.; Strain, B. R.

1988-01-01

Mungbean (Phaseolus aureus Roxb.) seedlings were grown hypobarically to assess the effects of low pressure (21-24 kilopascals) on growth and mitochondrial respiration. Control seedlings grown at ambient pressure (101 kilopascals) were provided amounts of O2 equivalent to those provided experimental seedlings at reduced pressure to factor out responses to O2 concentration and to total pressure. Respiration was assayed using washed mitochondria, and was found to respond only to O2 concentration. Regardless of total pressure, seedlings grown at 2 millimoles O2 per liter had higher state 3 respiration rates and decreased percentages of alternative respiration compared to ambient (8.4 millimoles O2 per liter) controls. In contrast, seedling growth responded to total pressure but not to O2 concentration. Seedlings were significantly larger when grown under low pressure. While low O2 (2 millimoles O2 per liter) diminished growth at ambient pressure, growth at low pressure in the same oxygen concentration was enhanced. Respiratory development and growth of mungbean seedlings under low pressure is unimpaired whether oxygen or air is used as the chamber gas, and further, low pressure can improve growth under conditions of poor aeration.

Uptake and translocation of phytochemical 2-benzoxazolinone (BOA) in radish seeds and seedlings.

PubMed

Chiapusio, Geneviève; Pellissier, François; Gallet, Christiane

2004-07-01

The molecular aspects of phytochemical interactions between plants, especially the process of phytochemical translocation by the target plant, remain challenging for those studying allelopathy. 2-Benzoxazolinone (BOA) is a natural chemical produced by rye (Secale cereale) and is known to have phytotoxic effects on weed seeds and seedlings. The translocation of BOA into target plants has been poorly investigated. Therefore, the total absorption of [ring U 14C] BOA was estimated by oxidizing whole seedlings of Raphanus sativus cv. for 8 days and quantifying the radioactivity. Non-radiolabelled BOA in seedlings was also estimated by HPLC. BOA applied at 10(-3) M was readily taken up by germinated radish at a rate of 1556 nmol g(-1) FW. At these same concentrations, BOA reduced radish germination by 50% and caused a delay in radicle elongation. Exogenous BOA was responsible for the observed germination inhibition. At a concentration of 10(-5) M, BOA was taken up by germinated seeds (31 nmol g(-1) FW), but this quantity did not affect radish germination. Labelled BOA was not mineralized in the culture medium during seedling growth as no 14CO2 was recovered. Both 10(-3) and 10(-5) M BOA were translocated into radish organs, mainly into roots and cotyledons. These organs were then identified as potential physiological target sites. Cotyledons remained the target sink (44% of the total radioactivity). The kinetics of BOA uptake at 10(-3) and 10(-5) M in radish seedlings was identical: BOA accumulation was proportional to its initial concentration. A comparison between radioactivity and HPLC quantification for 10(-3) M BOA indicated that BOA (along with some metabolites) could effectively be recovered in radish organs using chromatography.

Detection of QTLs for seedling characteristics in barley (Hordeum vulgare L.) grown under hydroponic culture condition.

PubMed

Wang, Qifei; Sun, Genlou; Ren, Xifeng; Wang, Jibin; Du, Binbin; Li, Chengdao; Sun, Dongfa

2017-11-07

Seedling characteristics play significant roles in the growth and development of barley (Hordeum vulgare L.), including stable stand establishment, water and nutrients uptake, biotic resistance and abiotic stresses, and can influence yield and quality. However, the genetic mechanisms underlying seedling characteristics in barley are largely unknown and little research has been done. In the present work, 21 seedling-related characteristics are assessed in a barley double haploid (DH) population, grown under hydroponic conditions. Of them, leaf age (LAG), shoot height (SH), maximum root length (MRL), main root number (MRN) and seedling fresh weight (SFW) were investigated at the 13th, 20th, 27th, and 34th day after germination. The objectives were to identify quantitative trait loci (QTLs) underlying these seedling characteristics using a high-density linkage map and to reveal the QTL expression pattern by comparing the QTLs among four different seedling growth stages. A total of 70 QTLs were distributed over all chromosomes except 4H, and, individually, accounted for 5.01%-77.78% of phenotypic variation. Out of the 70 detected QTLs, 23 showed a major effect on 14 seedling-related characteristics. Ten co-localized chromosomal regions on 2H (five regions), 3H (two regions) and 7H (three regions) involved 39 QTLs (55.71%), each simultaneously influenced more than one trait. Meanwhile, 9 co-localized genomic regions involving 22 QTLs for five seedling characteristics (LAG, SH, MRL, MRN and SFW) at the 13th, 20th, 27th and 34th day-old seedling were common for two or more growth stages of seedling. QTL in the vicinity of Vrs1 locus on chromosome 2H with the favorable alleles from Huadamai 6 was found to have the largest main effects on multiple seedling-related traits. Six QTL cluster regions associated with 16 seedling-related characteristics were observed on chromosome 2H, 3H and 7H. The majority of the 29 regions identified for five seedling characteristics were selectively expressed at different developmental stages. The genetic effects of 9 consecutive expression regions displayed different developmental influences at different developmental stages. These findings enhanced our understanding of a genetic basis underlying seedling characteristics in barley. Some QTLs detected here could be used for marker-assisted selection (MAS) in barley breeding.

Calcium Deficiency of Dark-grown Seedlings of Phaseolus vulgaris L.

PubMed

Helms, K

1971-06-01

Hypocotyl collapse in dark-grown seedlings of Phaseolus vulgaris cv. Pinto was due to calcium deficiency. There was no evidence of an associated pathogen. The number of seedlings with hypocotyl collapse decreased and the mean hypocotyl length increased when increasing levels of calcium (0-100 micrograms per gram) were supplied in an external nutrient solution to seedlings grown under sterile conditions.When seedlings were supplied with a complete nutrient solution, containing calcium at 100 micrograms per gram, but minus potassium, magnesium, sulfur, nitrogen, or phosphorus, occasional plants developed hypocotyl collapse symptoms; however, the lengths of hypocotyls varied little from those of controls grown in complete nutrient. When the calcium level in the deficient nutrient solutions was raised to 200 micrograms per gram, the number of plants with hypocotyl collapse was reduced markedly.With complete nutrient solution minus calcium, seedlings developed symptoms of calcium deficiency irrespective of seed size, i.e., irrespective of whether or not the seed contained a total calcium content that was low or relatively high.An increase in hypocotyl length in response to an external supply of calcium was obtained with five cultivars of Phaseolus vulgaris L. and with one of Soja max Piper. A similar response to calcium was obtained for epicotyl growth of a cultivar of Vicia faba L., but not for a cultivar of Pisum sativum L.

Association analysis of single nucleotide polymorphisms in candidate genes with root traits in maize (Zea mays L.) seedlings.

PubMed

Kumar, Bharath; Abdel-Ghani, Adel H; Pace, Jordon; Reyes-Matamoros, Jenaro; Hochholdinger, Frank; Lübberstedt, Thomas

2014-07-01

Several genes involved in maize root development have been isolated. Identification of SNPs associated with root traits would enable the selection of maize lines with better root architecture that might help to improve N uptake, and consequently plant growth particularly under N deficient conditions. In the present study, an association study (AS) panel consisting of 74 maize inbred lines was screened for seedling root traits in 6, 10, and 14-day-old seedlings. Allele re-sequencing of candidate root genes Rtcl, Rth3, Rum1, and Rul1 was also carried out in the same AS panel lines. All four candidate genes displayed different levels of nucleotide diversity, haplotype diversity and linkage disequilibrium. Gene based association analyses were carried out between individual polymorphisms in candidate genes, and root traits measured in 6, 10, and 14-day-old maize seedlings. Association analyses revealed several polymorphisms within the Rtcl, Rth3, Rum1, and Rul1 genes associated with seedling root traits. Several nucleotide polymorphisms in Rtcl, Rth3, Rum1, and Rul1 were significantly (P<0.05) associated with seedling root traits in maize suggesting that all four tested genes are involved in the maize root development. Thus considerable allelic variation present in these root genes can be exploited for improving maize root characteristics. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Expression Patterns of Glutathione Transferase Gene (GstI) in Maize Seedlings Under Juglone-Induced Oxidative Stress

PubMed Central

Sytykiewicz, Hubert

2011-01-01

Juglone (5-hydroxy-1,4-naphthoquinone) has been identified in organs of many plant species within Juglandaceae family. This secondary metabolite is considered as a highly bioactive substance that functions as direct oxidant stimulating the production of reactive oxygen species (ROS) in acceptor plants. Glutathione transferases (GSTs, E.C.2.5.1.18) represent an important group of cytoprotective enzymes participating in detoxification of xenobiotics and limiting oxidative damages of cellular macromolecules. The purpose of this study was to investigate the impact of tested allelochemical on growth and development of maize (Zea mays L.) seedlings. Furthermore, the effect of juglone-induced oxidative stress on glutathione transferase (GstI) gene expression patterns in maize seedlings was recorded. It was revealed that 4-day juglone treatment significantly stimulated the transcriptional activity of GstI in maize seedlings compared to control plants. By contrast, at the 6th and 8th day of experiments the expression gene responses were slightly lower as compared with non-stressed seedlings. Additionally, the specific gene expression profiles, as well as the inhibition of primary roots and coleoptile elongation were proportional to juglone concentrations. In conclusion, the results provide strong molecular evidence that allelopathic influence of juglone on growth and development of maize seedlings may be relevant with an induction of oxidative stress in acceptor plants. PMID:22174645

Fungal Disease Prevention in Seedlings of Rice (Oryza sativa) and Other Grasses by Growth-Promoting Seed-Associated Endophytic Bacteria from Invasive Phragmites australis

PubMed Central

Verma, Satish K.; Kingsley, Kathryn L.; Bergen, Marshall S.; White, James F.

2018-01-01

Non-cultivated plants carry microbial endophytes that may be used to enhance development and disease resistance of crop species where growth-promoting and protective microbes may have been lost. During seedling establishment, seedlings may be infected by several fungal pathogens that are seed or soil borne. Several species of Fusarium, Pythium and other water moulds cause seed rots during germination. Fusarium blights of seedlings are also very common and significantly affect seedling development. In the present study we screened nine endophytic bacteria isolated from the seeds of invasive Phragmites australis by inoculating onto rice, Bermuda grass (Cynodon dactylon), or annual bluegrass (Poa annua) seeds to evaluate plant growth promotion and protection from disease caused by Fusarium oxysporum. We found that three bacteria belonging to genus Pseudomonas spp. (SLB4-P. fluorescens, SLB6-Pseudomonas sp. and SY1-Pseudomonas sp.) promoted seedling development, including enhancement of root and shoot growth, and stimulation of root hair formation. These bacteria were also found to increase phosphate solubilization in in vitro experiments. Pseudomonas sp. (SY1) significantly protected grass seedlings from Fusarium infection. In co-culture experiments, strain SY1 strongly inhibited fungal pathogens with 85.71% growth inhibition of F. oxysporum, 86.33% growth inhibition of Curvularia sp. and 82.14% growth inhibition of Alternaria sp. Seedlings previously treated with bacteria were found much less infected by F. oxysporum in comparison to non-treated controls. On microscopic observation we found that bacteria appeared to degrade fungal mycelia actively. Metabolite products of strain SY1 in agar were also found to inhibit fungal growth on nutrient media. Pseudomonas sp. (SY1) was found to produce antifungal volatiles. Polymerase chain reaction (PCR) amplification using specific primers for pyrrolnitirin synthesis and HCN (hydrogen cyanide) production suggested presence of genes for both compounds in the genome of SY1. HCN was detected in cultures of SY1. We conclude that microbes from non-cultivated plants may provide disease protection and promote growth of crop plants. PMID:29518024

Fungal Disease Prevention in Seedlings of Rice (Oryza sativa) and Other Grasses by Growth-Promoting Seed-Associated Endophytic Bacteria from Invasive Phragmites australis.

PubMed

Verma, Satish K; Kingsley, Kathryn L; Bergen, Marshall S; Kowalski, Kurt P; White, James F

2018-03-08

Non-cultivated plants carry microbial endophytes that may be used to enhance development and disease resistance of crop species where growth-promoting and protective microbes may have been lost. During seedling establishment, seedlings may be infected by several fungal pathogens that are seed or soil borne. Several species of Fusarium , Pythium and other water moulds cause seed rots during germination. Fusarium blights of seedlings are also very common and significantly affect seedling development. In the present study we screened nine endophytic bacteria isolated from the seeds of invasive Phragmites australis by inoculating onto rice, Bermuda grass ( Cynodon dactylon ), or annual bluegrass ( Poa annua ) seeds to evaluate plant growth promotion and protection from disease caused by Fusarium oxysporum . We found that three bacteria belonging to genus Pseudomonas spp. (SLB4- P. fluorescens , SLB6- Pseudomonas sp. and SY1- Pseudomonas sp.) promoted seedling development, including enhancement of root and shoot growth, and stimulation of root hair formation. These bacteria were also found to increase phosphate solubilization in in vitro experiments. Pseudomonas sp. (SY1) significantly protected grass seedlings from Fusarium infection. In co-culture experiments, strain SY1 strongly inhibited fungal pathogens with 85.71% growth inhibition of F. oxysporum , 86.33% growth inhibition of Curvularia sp. and 82.14% growth inhibition of Alternaria sp. Seedlings previously treated with bacteria were found much less infected by F. oxysporum in comparison to non-treated controls. On microscopic observation we found that bacteria appeared to degrade fungal mycelia actively. Metabolite products of strain SY1 in agar were also found to inhibit fungal growth on nutrient media. Pseudomonas sp. (SY1) was found to produce antifungal volatiles. Polymerase chain reaction (PCR) amplification using specific primers for pyrrolnitirin synthesis and HCN (hydrogen cyanide) production suggested presence of genes for both compounds in the genome of SY1. HCN was detected in cultures of SY1. We conclude that microbes from non-cultivated plants may provide disease protection and promote growth of crop plants.

Fungal disease prevention in seedlings of rice (Oryza sativa) and other grasses by growth-promoting seed-associated endophytic bacteria from invasive Phragmites australis

USGS Publications Warehouse

Verma, Satish K.; Kingsley, Kathryn L.; Bergen, Marshall S.; Kowalski, Kurt P.; White, James F.

2018-01-01

Non-cultivated plants carry microbial endophytes that may be used to enhance development and disease resistance of crop species where growth-promoting and protective microbes may have been lost. During seedling establishment, seedlings may be infected by several fungal pathogens that are seed or soil borne. Several species of Fusarium, Pythium and other water moulds cause seed rots during germination. Fusariumblights of seedlings are also very common and significantly affect seedling development. In the present study we screened nine endophytic bacteria isolated from the seeds of invasive Phragmites australis by inoculating onto rice, Bermuda grass (Cynodon dactylon), or annual bluegrass (Poa annua) seeds to evaluate plant growth promotion and protection from disease caused by Fusarium oxysporum. We found that three bacteria belonging to genus Pseudomonas spp. (SLB4-P. fluorescens, SLB6-Pseudomonas sp. and SY1-Pseudomonassp.) promoted seedling development, including enhancement of root and shoot growth, and stimulation of root hair formation. These bacteria were also found to increase phosphate solubilization in in vitro experiments. Pseudomonas sp. (SY1) significantly protected grass seedlings from Fusarium infection. In co-culture experiments, strain SY1 strongly inhibited fungal pathogens with 85.71% growth inhibition of F. oxysporum, 86.33% growth inhibition of Curvularia sp. and 82.14% growth inhibition of Alternaria sp. Seedlings previously treated with bacteria were found much less infected by F. oxysporum in comparison to non-treated controls. On microscopic observation we found that bacteria appeared to degrade fungal mycelia actively. Metabolite products of strain SY1 in agar were also found to inhibit fungal growth on nutrient media. Pseudomonas sp. (SY1) was found to produce antifungal volatiles. Polymerase chain reaction (PCR) amplification using specific primers for pyrrolnitirin synthesis and HCN (hydrogen cyanide) production suggested presence of genes for both compounds in the genome of SY1. HCN was detected in cultures of SY1. We conclude that microbes from non-cultivated plants may provide disease protection and promote growth of crop plants.

Development of EST-SSR markers for Elaeocarpus photiniifolia (Elaeocarpaceae), an endemic taxon of the Bonin Islands.

PubMed

Sugai, Kyoko; Setsuko, Suzuki; Uchiyama, Kentaro; Murakami, Noriaki; Kato, Hidetoshi; Yoshimaru, Hiroshi

2012-02-01

Expressed sequence tag (EST)-derived microsatellite markers were developed for Elaeocarpus photiniifolia, an endemic taxon of the Bonin Islands. Initially, a complementary DNA (cDNA) library was constructed by de novo pyrosequencing of total RNA extracted from a seedling. A total of 267 primer pairs were designed from the library. Of the 48 tested loci, 25 loci were polymorphic among 41 individuals representing the entire geographical range of the species, with the number of alleles per locus and expected heterozygosity ranging from two to 14 and 0.09 to 0.86, respectively. Most loci were transferable to a related species, E. sylvestris. The developed markers will be useful for evaluating the genetic structure of E. photiniifolia.

Sequential and coordinated action of phytochromes A and B during Arabidopsis stem growth revealed by kinetic analysis

NASA Technical Reports Server (NTRS)

Parks, B. M.; Spalding, E. P.; Evans, M. L. (Principal Investigator)

1999-01-01

Photoreceptor proteins of the phytochrome family mediate light-induced inhibition of stem (hypocotyl) elongation during the development of photoautotrophy in seedlings. Analyses of overt mutant phenotypes have established the importance of phytochromes A and B (phyA and phyB) in this developmental process, but kinetic information that would augment emerging molecular models of phytochrome signal transduction is absent. We have addressed this deficiency by genetically dissecting phytochrome-response kinetics, after having solved the technical issues that previously limited growth studies of small Arabidopsis seedlings. We show here, with resolution on the order of minutes, that phyA initiated hypocotyl growth inhibition upon the onset of continuous red light. This primary contribution of phyA began to decrease after 3 hr of irradiation, the same time at which immunochemically detectable phyA disappeared and an exclusively phyB-dependent phase of inhibition began. The sequential and coordinated actions of phyA and phyB in red light were not observed in far-red light, which inhibited growth persistently through an exclusively phyA-mediated pathway.

Effect of osmopriming on germination and initial growth of Physalis angulata L. under salt stress and on expression of associated genes.

PubMed

Souza, Manuela O DE; Pelacani, Claudinéia R; Willems, Leo A J; Castro, Renato D DE; Hilhorst, Henk W M; Ligterink, Wilco

2016-01-01

This study aimed to evaluate the effects of priming on seed germination under salt stress and gene expression in seeds and seedlings of P. angulata L. After priming for 10 days, seed germination was tested in plastic trays containing 15 ml of water (0 dS m-1 - control) or 15 ml of NaCl solution (2, 4, 6, 8, 10, 12, 14 and 16 dS m-1). Fresh and dry weight of shoots and roots of seedlings were evaluated at 0, 2, 4, 6, 8 dS m-1. Total RNA was extracted from whole seeds and seedlings followed by RT-qPCR. The target genes selected for this study were: ascorbate peroxidase (APX), glutathione-S-transferase (GST), thioredoxin (TXN), high affinity potassium transporter protein 1 (HAK1) and salt overly sensitive 1 (SOS1). At an electroconductivity of 14 dS m-1 the primed seeds still germinated to 72%, in contrast with the non-primed seeds which did not germinate. The relative expression of APX was higher in primed seeds and this may have contributed to the maintenance of high germination in primed seeds at high salt concentrations. GST and TXN displayed increased transcript levels in shoots and roots of seedlings from primed seeds. Priming improved seed germination as well as salt tolerance and this is correlated with increased expression of APX in seeds and SOS1, GST and TXN in seedlings.

A Gate-to-gate Case Study of the Life Cycle Assessment of an Oil Palm Seedling

PubMed Central

Muhamad, Halimah; Sahid, Ismail Bin; Surif, Salmijah; Ai, Tan Yew; May, Choo Yuen

2012-01-01

The palm oil industry has played an important role in the economic development of Malaysia and has enhanced the economic welfare of its people. To determine the environmental impact of the oil palm seedling at the nursery stage, information on inputs and outputs need to be assessed. The oil palm nursery is the first link in the palm oil supply chain. A gate-to-gate study was carried out whereby the system boundary was set to only include the process of the oil palm seedling. The starting point was a germinated seed in a small polyethylene bag (6 in × 9 in) in which it remained until the seedling was approximately 3 to 4 months old. The seedling was then transferred into a larger polyethylene bag (12 in × 15 in), where it remained until it was 10–12 months old, when it was planted in the field (plantation). The functional unit for this life cycle inventory (LCI) is based on the production of one seedling. Generally, within the system boundary, the production of an oil palm seedling has only two major environmental impact points, the polybags used to grow the seedling and the fungicide (dithiocarbamate) used to control pathogenic fungi, as both the polybags and the dithiocarbamate are derived from fossil fuel. PMID:24575222

Elevated Temperature and CO2 Stimulate Late-Season Photosynthesis But Impair Cold Hardening in Pine.

PubMed

Chang, Christine Y; Fréchette, Emmanuelle; Unda, Faride; Mansfield, Shawn D; Ensminger, Ingo

2016-10-01

Rising global temperature and CO 2 levels may sustain late-season net photosynthesis of evergreen conifers but could also impair the development of cold hardiness. Our study investigated how elevated temperature, and the combination of elevated temperature with elevated CO 2 , affected photosynthetic rates, leaf carbohydrates, freezing tolerance, and proteins involved in photosynthesis and cold hardening in Eastern white pine (Pinus strobus). We designed an experiment where control seedlings were acclimated to long photoperiod (day/night 14/10 h), warm temperature (22°C/15°C), and either ambient (400 μL L -1 ) or elevated (800 μmol mol -1 ) CO 2 , and then shifted seedlings to growth conditions with short photoperiod (8/16 h) and low temperature/ambient CO 2 (LTAC), elevated temperature/ambient CO 2 (ETAC), or elevated temperature/elevated CO 2 (ETEC). Exposure to LTAC induced down-regulation of photosynthesis, development of sustained nonphotochemical quenching, accumulation of soluble carbohydrates, expression of a 16-kD dehydrin absent under long photoperiod, and increased freezing tolerance. In ETAC seedlings, photosynthesis was not down-regulated, while accumulation of soluble carbohydrates, dehydrin expression, and freezing tolerance were impaired. ETEC seedlings revealed increased photosynthesis and improved water use efficiency but impaired dehydrin expression and freezing tolerance similar to ETAC seedlings. Sixteen-kilodalton dehydrin expression strongly correlated with increases in freezing tolerance, suggesting its involvement in the development of cold hardiness in P. strobus Our findings suggest that exposure to elevated temperature and CO 2 during autumn can delay down-regulation of photosynthesis and stimulate late-season net photosynthesis in P. strobus seedlings. However, this comes at the cost of impaired freezing tolerance. Elevated temperature and CO 2 also impaired freezing tolerance. However, unless the frequency and timing of extreme low-temperature events changes, this is unlikely to increase risk of freezing damage in P. strobus seedlings. © 2016 American Society of Plant Biologists. All Rights Reserved.

Elevated Temperature and CO2 Stimulate Late-Season Photosynthesis But Impair Cold Hardening in Pine[OPEN

PubMed Central

2016-01-01

Rising global temperature and CO2 levels may sustain late-season net photosynthesis of evergreen conifers but could also impair the development of cold hardiness. Our study investigated how elevated temperature, and the combination of elevated temperature with elevated CO2, affected photosynthetic rates, leaf carbohydrates, freezing tolerance, and proteins involved in photosynthesis and cold hardening in Eastern white pine (Pinus strobus). We designed an experiment where control seedlings were acclimated to long photoperiod (day/night 14/10 h), warm temperature (22°C/15°C), and either ambient (400 μL L−1) or elevated (800 μmol mol−1) CO2, and then shifted seedlings to growth conditions with short photoperiod (8/16 h) and low temperature/ambient CO2 (LTAC), elevated temperature/ambient CO2 (ETAC), or elevated temperature/elevated CO2 (ETEC). Exposure to LTAC induced down-regulation of photosynthesis, development of sustained nonphotochemical quenching, accumulation of soluble carbohydrates, expression of a 16-kD dehydrin absent under long photoperiod, and increased freezing tolerance. In ETAC seedlings, photosynthesis was not down-regulated, while accumulation of soluble carbohydrates, dehydrin expression, and freezing tolerance were impaired. ETEC seedlings revealed increased photosynthesis and improved water use efficiency but impaired dehydrin expression and freezing tolerance similar to ETAC seedlings. Sixteen-kilodalton dehydrin expression strongly correlated with increases in freezing tolerance, suggesting its involvement in the development of cold hardiness in P. strobus. Our findings suggest that exposure to elevated temperature and CO2 during autumn can delay down-regulation of photosynthesis and stimulate late-season net photosynthesis in P. strobus seedlings. However, this comes at the cost of impaired freezing tolerance. Elevated temperature and CO2 also impaired freezing tolerance. However, unless the frequency and timing of extreme low-temperature events changes, this is unlikely to increase risk of freezing damage in P. strobus seedlings. PMID:27591187

Photosynthetic sucrose acts as cotyledon-derived long-distance signal to control root growth during early seedling development in Arabidopsis

PubMed Central

Kircher, Stefan; Schopfer, Peter

2012-01-01

The most hazardous span in the life of green plants is the period after germination when the developing seedling must reach the state of autotrophy before the nutrients stored in the seed are exhausted. The need for an economically optimized utilization of limited resources in this critical period is particularly obvious in species adopting the dispersal strategy of producing a large amount of tiny seeds. The model plant Arabidopsis thaliana belongs to this category. Arabidopsis seedlings promote root development only in the light. This response to light has long been recognized and recently discussed in terms of an organ-autonomous feature of photomorphogenesis directed by the red/blue light absorbing photoreceptors phytochrome and cryptochrome and mediated by hormones such as auxin and/or gibberellin. Here we show that the primary root of young Arabidopsis seedlings responds to an interorgan signal from the cotyledons and that phloem transport of photosynthesis-derived sugar into the root tip is necessary and sufficient for the regulation of root elongation growth by light. PMID:22733756

Salix alba and Populus nigra seedlings resistance to physical hydro-sedimentary stresses: nursery experimental approach compared to in situ measurements

NASA Astrophysics Data System (ADS)

Wintenberger, Coraline; Rodrigues, Stephane; Breheret, Jean-Gabriel; Jugé, Philippe; Villar, Marc

2014-05-01

In Europe, riparian Salicaceae is declining following the loss of potential germination areas associated with river management. Nevertheless, as an exception for lowland rivers, the Loire River (France) shows in its middle reaches an efficient sexual regeneration of Populus nigra and Salix alba species on bare sediments deposited during flood events. The study focuses on the influence of flow, sediment dynamics and fluvial maintenance operations on the establishment and survival of black poplar and white willow seedlings during the first year of development in a lowland sandy-gravel river, the Middle Loire. Main questions are: what is the influence of morphological and sedimentary features on seedlings recruitment and how do they withstand the hydro-sedimentary stresses occurring during high flow periods? How fluvial management works, and induced morphology and sedimentary features, modify the sediment dynamics and subsequent establishment and maintenance of seedlings? To answer these questions, we developed an ex-situ approach which allowed, under controlled conditions, to determine the influence of the sedimentological characteristics of the substrate on the development and maintenance of seedlings with a specific focus on the root system. Three experiments were carried out for three sedimentary mixtures from the river (sand, sand-gravel and 0.2 m of sand superimposed on sand-gravel mixture) that correspond to grain size and stratigraphy conditions often observed on bars and secondary channels in the Loire. The experimental design includes 108 plots of 1 m3, with 400 seeds per plot (corresponding to the Loire density measurements) and combining seeds from two species, three sedimentary mixtures, four replicates and three experiments. Experiment 1 (control) is based on the architecture of root systems using the WinRHIZO image analysis software. Experiment 2 is relative to the evaluation of constraints leading to "uprooting" of seedlings. Experiment 3 provides data on the seedlings survival once buried during a flood event. Genetic diversity of the seed lots will be investigated via biomass and shoot / root ratio. Results reveal that willow seedlings have a higher density of roots compared to poplar. In sand mixture, poplar has a taproot system; in sand-gravel mixture, taproot is divided into several roots which leads to a branched root system. The required forces to uprooting are twice much important for sand-gravel mixture. In situ measurements detail the sediment dynamics and morphological evolution during and after floods (topography, scour/fill processes, grain size surveys, flow velocity, sediment transport rates) on a managed alluvial bar. Results associated with floods occurring after fluvial management works highlight the rapid regeneration of bedforms associated with sedimentary and hydraulics constraints. This leads to the development of new morphological and sedimentological units, suitable for seedlings recruitment. Thirty plots measurements of seedlings (densities and species) established were associated with these news physical conditions over the bar. Black poplar and white willow appeared for a wide range of grain sizes and on specific morphological units. Seedlings survival will be analyzed with regard to physical constraints determined for each plot from measurements of hydro-sedimentary dynamics and then compared to ex situ results.

Effect of Pre-Harvest Shade Control and Fencing on Northern Red oak Seedling Development in the Central Appalachians

Treesearch

Gary W. Miller; James N. Kochenerfer; Kurt W. Gottschalk

2004-01-01

Successful oak regeneration is related to the size and number of advanced seedlings present when harvests occur. This study was installed to quantify the effect of microsite light availability and deer on the development of advanced northern red oak (Quercus rubra L.) reproduction in mesic Appalachian hardwood stands. Microsite light was manipulated...

Delayed prescribed burning in a seedling and sapling Longleaf Pine plantation in Louisiana

Treesearch

James D. Haywood

2002-01-01

To examine the effects of delaying prescribed burning for several years, I initiated five treatments in a 5- to 6-year-old longleaf pine stand: a check of no control; biennial hardwood control by directed chemical application; and biennial burning in either early March, May, or July. After the initial burns, longleaf pine survival decreased from 82 percent in February...

Karrikins: Regulators Involved in Phytohormone Signaling Networks during Seed Germination and Seedling Development

PubMed Central

Meng, Yongjie; Shuai, Haiwei; Luo, Xiaofeng; Chen, Feng; Zhou, Wenguan; Yang, Wenyu; Shu, Kai

2017-01-01

Seed germination and early seedling establishment are critical stages during a plant’s life cycle. These stages are precisely regulated by multiple internal factors, including phytohormones and environmental cues such as light. As a family of small molecules discovered in wildfire smoke, karrikins (KARs) play a key role in various biological processes, including seed dormancy release, germination regulation, and seedling establishment. KARs show a high similarity with strigolactone (SL) in both chemical structure and signaling transduction pathways. Current evidence shows that KARs may regulate seed germination by mediating the biosynthesis and/or signaling transduction of abscisic acid (ABA), gibberellin (GA) and auxin [indoleacetic acid (IAA)]. Interestingly, KARs regulate seed germination differently in different species. Furthermore, the promotion effect on seedling establishment implies that KARs have a great potential application in alleviating shade avoidance response, which attracts more and more attention in plant molecular biology. In these processes, KARs may have complicated interactions with phytohormones, especially with IAA. In this updated review, we summarize the current understanding of the relationship between KARs and SL in the chemical structure, signaling pathway and the regulation of plant growth and development. Further, the crosstalk between KARs and phytohormones in regulating seed germination and seedling development and that between KARs and IAA during shade responses are discussed. Finally, future challenges and research directions for the KAR research field are suggested. PMID:28174573

Association analysis of genes involved in maize (Zea mays L.) root development with seedling and agronomic traits under contrasting nitrogen levels.

PubMed

Abdel-Ghani, Adel H; Kumar, Bharath; Pace, Jordon; Jansen, Constantin; Gonzalez-Portilla, Pedro J; Reyes-Matamoros, Jenaro; San Martin, Juan Pablo; Lee, Michael; Lübberstedt, Thomas

2015-05-01

A better understanding of the genetic control of root development might allow one to develop lines with root systems with the potential to adapt to soils with limited nutrient availability. For this purpose, an association study (AS) panel consisting of 74 diverse set of inbred maize lines were screened for seedling root traits and adult plant root traits under two contrasting nitrogen (N) levels (low and high N). Allele re-sequencing of RTCL, RTH3, RUM1, and RUL1 genes related to root development was carried out for AS panel lines. Association analysis was carried out between individual polymorphisms, and both seedling and adult plant traits, while controlling for spurious associations due to population structure and kinship relations. Based on the SNPs identified in RTCL, RTH3, RUM1, and RUL1, lines within the AS panel were grouped into 16, 9, 22, and 7 haplotypes, respectively. Association analysis revealed several polymorphisms within root genes putatively associated with the variability in seedling root and adult plant traits development under contrasting N levels. The highest number of significantly associated SNPs with seedling root traits were found in RTCL (19 SNPs) followed by RUM1 (4 SNPs) and in case of RTH3 and RUL1, two and three SNPs, respectively, were significantly associated with root traits. RTCL and RTH3 were also found to be associated with grain yield. Thus considerable allelic diversity is present within the candidate genes studied and can be utilized to develop functional markers that allow identification of maize lines with improved root architecture and yield under N stress conditions.

Seedling growth and development on space shuttle

NASA Astrophysics Data System (ADS)

Cowles, J.; Lemay, R.; Jahns, G.

1994-11-01

Young pine seedlings, and mung bean and oat seeds were flown on shuttle flights, STS-3 and STS-51F, in March, 1982 and July/August, 1985, respectively. The plant growth units built to support the two experiments functioned mechanically as anticipated and provided the necessary support data. Pine seedlings exposed to the microgravity environment of the space shuttle for 8 days continued to grow at a rate similar to ground controls. Pine stems in flight seedlings, however, averaged 10 to 12% less lignin than controls. Flight mung beans grew slower than control beans and their stems contained about 25% less lignin than control seedlings. Reduced mung bean growth in microgravity was partly due to slower germination rate. Lignin also was reduced in flight oats as compared to controls. Oats and mung beans exhibited upward growing roots which were not observed in control seedlings. Chlorophll A/B ratios were lower in flight tissues than controls. The sealed PGCs exhibited large variations in atmospheric gas composition but the changes were similar between flight and ground controls. Ethylene was present in low concentrations in all chambers.

Seedling growth and development on space shuttle

NASA Technical Reports Server (NTRS)

Cowles, J.; Lemay, R.; Jahns, G.

1994-01-01

Young pine seedlings, and mung bean and oat seeds were flown on shuttle flights, STS-3 and STS-51F, in March, 1982 and July/August, 1985, respectively. The plant growth units built to support the two experiments functioned mechanically as anticipated and provided the necessary support data. Pine seedlings exposed to the microgravity environment of the space shuttle for 8 days continued to grow at a rate similar to ground controls. Pine stems in flight seedlings, however, averaged 10 to 12% less lignin than controls. Flight mung beans grew slower than control beans and their stems contained about 25% less lignin than control seedlings. Reduced mung bean growth in microgravity was partly due to slower germination rate. Lignin also was reduced in flight oats as compared to controls. Oats and mung beans exhibited upward growing roots which were not observed in control seedlings. Chlorophyll A/B ratios were lower in flight tissues than controls. The sealed PGCs exhibited large variations in atmospheric gas composition but the changes were similar between flight and ground controls. Ethylene was present in low concentrations in all chambers.

Identification of seedling cabbages and weeds using hyperspectral imaging

USDA-ARS?s Scientific Manuscript database

Target detectionis one of research focues for precision chemical application. This study developed a method to identify seedling cabbages and weeds using hyperspectral spectral imaging. In processing the image data, with ENVI software, after dimension reduction, noise reduction, de-correlation for h...

The use of compost in afforestation of Mediterranean areas: Effects on soil properties and young tree seedlings.

PubMed

Larchevêque, Marie; Ballini, Christine; Korboulewsky, Nathalie; Montès, Nicolas

2006-10-01

In Mediterranean frequently burnt areas, fire and erosion result in the decrease of soil fertility, so afforestation is a major concern. We carried out an in situ experiment of compost amendment to improve survival and growth of planted tree seedlings. One-year-tree seedlings of native species (Quercus ilex, Pinus halepensis and Pinus pinea) were planted on a frequently burnt calcareous site. Three rates of fresh co-composted sewage sludge and greenwastes (control without compost, 20 and 40 kg m(-2) of compost) were incorporated into the soil at each seedling stem. Changes of soil properties and tree development were studied during 3 years (2001-2003) and 2 years (2002-2003) respectively. The compost improved survival of Quercus ilex and Pinus pinea seedlings in severe drought conditions, but had no effect on Pinus halepensis. For all species seedling length and radial growth and NPK nutrition were increased for both rates of amendment. Amendment improved soil fertility, but available P concentration increased 13 fold in the neighbouring soil of seedlings amended at the maximal rate compared to control. However, amendment did not significantly increase concentrations of Cd, Cr, Ni and Pb in soils or tree seedlings. It increased Cu and Zn total and available concentrations in soils, while foliar Cu and Zn concentrations in the seedlings remained similar in all plots. Compost can efficiently help afforestation of dry soils with low organic matter content. However, sewage sludge concentrations in P, and to a lesser extent in Cu and Zn, limit rates of application that can be applied without environmental hazard.

Distinct Calcium Signaling Pathways Regulate Calmodulin Gene Expression in Tobacco1

PubMed Central

van der Luit, Arnold H.; Olivari, Claudio; Haley, Ann; Knight, Marc R.; Trewavas, Anthony J.

1999-01-01

Cold shock and wind stimuli initiate Ca2+ transients in transgenic tobacco (Nicotiana plumbaginifolia) seedlings (named MAQ 2.4) containing cytoplasmic aequorin. To investigate whether these stimuli initiate Ca2+ pathways that are spatially distinct, stress-induced nuclear and cytoplasmic Ca2+ transients and the expression of a stress-induced calmodulin gene were compared. Tobacco seedlings were transformed with a construct that encodes a fusion protein between nucleoplasmin (a major oocyte nuclear protein) and aequorin. Immunocytochemical evidence indicated targeting of the fusion protein to the nucleus in these plants, which were named MAQ 7.11. Comparison between MAQ 7.11 and MAQ 2.4 seedlings confirmed that wind stimuli and cold shock invoke separate Ca2+ signaling pathways. Partial cDNAs encoding two tobacco calmodulin genes, NpCaM-1 and NpCaM-2, were identified and shown to have distinct nucleotide sequences that encode identical polypeptides. Expression of NpCaM-1, but not NpCaM-2, responded to wind and cold shock stimulation. Comparison of the Ca2+ dynamics with NpCaM-1 expression after stimulation suggested that wind-induced NpCaM-1 expression is regulated by a Ca2+ signaling pathway operational predominantly in the nucleus. In contrast, expression of NpCaM-1 in response to cold shock is regulated by a pathway operational predominantly in the cytoplasm. PMID:10557218

Early Summer Drought Stress During the First Growing Year Stimulates Extra Shoot Growth in Oak Seedlings (Quercus petraea)

PubMed Central

Turcsán, Arion; Steppe, Kathy; Sárközi, Edit; Erdélyi, Éva; Missoorten, Marc; Mees, Ghislain; Mijnsbrugge, Kristine V.

2016-01-01

More severe summer droughts are predicted for mid-latitudes in Europe. To evaluate the impact on forest ecosystems and more specifically on forest regeneration, we studied the response to summer drought in oak seedlings (Quercus petraea). Acorns were collected from different mother trees in three stands in Belgium, sown in pots and grown in non-heated greenhouse conditions. We imposed drought on the seedlings in early summer by first watering the pots to saturation and then stopping any watering. Weight of the pots and stomatal conductance were regularly measured. Re-watering followed this drought period of 5 weeks. Height of the seedlings and apical bud development were observed. Stomatal resistance increased toward the end of the experiment in the drought-treated group and was restored after re-watering. The seedlings from the drought treatment displayed a higher probability to produce additional shoot growth after re-watering (p ≤ 0.05). A higher competition for water (two plants per pot) increased this chance. Although this chance was also higher for smaller seedlings, the actual length of the extra growth after re-watering was higher for larger seedlings (p ≤ 0.01). Both in the drought-treated and in the control group the autochthonous provenance growing on a xeric site produced less extra shoots compared to the two other provenances. Finally, stressed plants showed less developed apical buds compared to the control group after re-watering, suggesting a phenological effect on the growth cycle of oaks (p ≤ 0.0001). The higher chance for an extra shoot growth after the drought period can be considered as a compensation for the induced growth arrest during the drought period. PMID:26941760

Climatic control of bud burst in young seedlings of nine provenances of Norway spruce.

PubMed

Søgaard, Gunnhild; Johnsen, Oystein; Nilsen, Jarle; Junttila, Olavi

2008-02-01

Detailed knowledge of temperature effects on the timing of dormancy development and bud burst will help evaluate the impacts of climate change on forest trees. We tested the effects of temperature applied during short-day treatment, duration of short-day treatment, duration of chilling and light regime applied during forcing on the timing of bud burst in 1- and 2-year-old seedlings of nine provenances of Norway spruce (Picea abies (L.) Karst.). High temperature during dormancy induction, little or no chilling and low temperature during forcing all delayed dormancy release but did not prevent bud burst or growth onset provided the seedlings were forced under long-day conditions. Without chilling, bud burst occurred in about 20% of seedlings kept in short days at 12 degrees C, indicating that young Norway spruce seedlings do not exhibit true bud dormancy. Chilling hastened bud burst and removed the long photoperiod requirement, but the effect of high temperature applied during dormancy induction was observed even after prolonged chilling. Extension of the short-day treatment from 4 to 8 or 12 weeks hastened bud burst. The effect of treatments applied during dormancy development was larger than that of provenance; in some cases no provenance effect was detected, but in 1-year-old seedlings, time to bud burst decreased linearly with increasing latitude of origin. Differences among provenances were complicated by different responses of some origins to light conditions under long-day forcing. In conclusion, timing of bud burst in Norway spruce seedlings is significantly affected by temperature during bud set, and these effects are modified by chilling and environmental conditions during forcing.

The effects of lead stress on photosynthetic function and chloroplast ultrastructure of Robinia pseudoacacia seedlings.

PubMed

Zhou, Jian; Jiang, Zeping; Ma, Jie; Yang, Lifeng; Wei, Yuan

2017-04-01

In this experiment, the effects of different lead (Pb) concentrations (0, 200, 600, 1000, 1400 mg kg -1 ) on photosynthesis and chlorophyll fluorescence in Robinia pseudoacacia seedlings were examined. As Pb concentration increased, chlorophyll a, chlorophyll b, total chlorophyll content, net photosynthetic rate, transpiration rate, stomatal conductance (g s ), and mesophyll intercellular carbon dioxide concentration were gradually reduced. Maximal photochemical efficiency, photochemical quenching, and quantum yield also decreased. However, the initial fluorescence and nonphotochemical quenching gradually increased. Chloroplasts swelled owing to local plasmolysis and lost most of their starch content, and their thylakoid lamellae gradually became disordered and loosely packed. When the chloroplast envelope was lost under high Pb stress (≥1000 mg kg -1 ), lipid globules were released into the surrounding mesophyll cell. Multiple regression analysis showed that g s and inactivity of the PSII reaction center had the greatest effect on photosynthetic function, whereas inhibition of electron transport had minimal effects on black locust seedlings under Pb stress.

Redox biology response in germinating Phaseolus vulgaris seeds exposed to copper: Evidence for differential redox buffering in seedlings and cotyledon.

PubMed

Karmous, Inès; Trevisan, Rafael; El Ferjani, Ezzeddine; Chaoui, Abdelilah; Sheehan, David

2017-01-01

In agriculture, heavy metal contamination of soil interferes with processes associated with plant growth, development and productivity. Here, we describe oxidative and redox changes, and deleterious injury within cotyledons and seedlings caused by exposure of germinating (Phaseolus vulgaris L. var. soisson nain hâtif) seeds to copper (Cu). Cu induced a marked delay in seedling growth, and was associated with biochemical disturbances in terms of intracellular oxidative status, redox regulation and energy metabolism. In response to these alterations, modulation of activities of antioxidant proteins (thioredoxin and glutathione reductase, peroxiredoxin) occurred, thus preventing oxidative damage. In addition, oxidative modification of proteins was detected in both cotyledons and seedlings by one- and two-dimensional electrophoresis. These modified proteins may play roles in redox buffering. The changes in activities of redox proteins underline their fundamental roles in controlling redox homeostasis. However, observed differential redox responses in cotyledon and seedling tissues showed a major capacity of the seedlings' redox systems to protect the reduced status of protein thiols, thus suggesting quantitatively greater antioxidant protection of proteins in seedlings compared to cotyledon. To our knowledge, this is the first comprehensive redox biology investigation of the effect of Cu on seed germination.

(Not) Keeping the stem straight: a proteomic analysis of maritime pine seedlings undergoing phototropism and gravitropism.

PubMed

Herrera, Raul; Krier, Catherine; Lalanne, Celine; Ba, El Hadji Maodo; Stokes, Alexia; Salin, Franck; Fourcaud, Thierry; Claverol, Stéphane; Plomion, Christophe

2010-10-06

Plants are subjected to continuous stimuli from the environment and have evolved an ability to respond through various growth and development processes. Phototropism and gravitropism responses enable the plant to reorient with regard to light and gravity. We quantified the speed of maritime pine seedlings to reorient with regard to light and gravity over 22 days. Seedlings were inclined at 15, 30 and 45 degrees with vertical plants as controls. A lateral light source illuminated the plants and stem movement over time was recorded. Depending on the initial angle of stem lean, the apical response to the lateral light source differed. In control and 15° inclined plants, the apex turned directly towards the light source after only 2 h. In plants inclined at 30° and 45°, the apex first reoriented in the vertical plane after 2 h, then turned towards the light source after 24 h. Two-dimensional gel electrophoresis coupled with mass spectrometry was then used to describe the molecular response of stem bending involved in photo- and gravi-tropism after 22 hr and 8 days of treatment. A total of 486 spots were quantitatively analyzed using image analysis software. Significant changes were determined in the protein accumulation of 68 protein spots. Early response gravitropic associated proteins were identified, which are known to function in energy related and primary metabolism. A group of thirty eight proteins were found to be involved in primary metabolism and energy related metabolic pathways. Degradation of Rubisco was implicated in some protein shifts. Our study demonstrates a rapid gravitropic response in apices of maritime pine seedlings inclined >30°. Little or no response was observed at the stem bases of the same plants. The primary gravitropic response is concomitant with a modification of the proteome, consisting of an over accumulation of energy and metabolism associated proteins, which may allow the stem to reorient rapidly after bending.

(Not) Keeping the stem straight: a proteomic analysis of maritime pine seedlings undergoing phototropism and gravitropism

PubMed Central

2010-01-01

Background Plants are subjected to continuous stimuli from the environment and have evolved an ability to respond through various growth and development processes. Phototropism and gravitropism responses enable the plant to reorient with regard to light and gravity. Results We quantified the speed of maritime pine seedlings to reorient with regard to light and gravity over 22 days. Seedlings were inclined at 15, 30 and 45 degrees with vertical plants as controls. A lateral light source illuminated the plants and stem movement over time was recorded. Depending on the initial angle of stem lean, the apical response to the lateral light source differed. In control and 15° inclined plants, the apex turned directly towards the light source after only 2 h. In plants inclined at 30° and 45°, the apex first reoriented in the vertical plane after 2 h, then turned towards the light source after 24 h. Two-dimensional gel electrophoresis coupled with mass spectrometry was then used to describe the molecular response of stem bending involved in photo- and gravi-tropism after 22 hr and 8 days of treatment. A total of 486 spots were quantitatively analyzed using image analysis software. Significant changes were determined in the protein accumulation of 68 protein spots. Early response gravitropic associated proteins were identified, which are known to function in energy related and primary metabolism. A group of thirty eight proteins were found to be involved in primary metabolism and energy related metabolic pathways. Degradation of Rubisco was implicated in some protein shifts. Conclusions Our study demonstrates a rapid gravitropic response in apices of maritime pine seedlings inclined >30°. Little or no response was observed at the stem bases of the same plants. The primary gravitropic response is concomitant with a modification of the proteome, consisting of an over accumulation of energy and metabolism associated proteins, which may allow the stem to reorient rapidly after bending. PMID:20925929

Accelerated development in Johnsongrass seedlings (Sorghum halepense) suppresses the growth of native grasses through size-asymmetric competition

PubMed Central

Meckel, Heather; Reichmann, Lara G.; Polley, H. Wayne; Fay, Philip A.

2017-01-01

Invasive plant species often dominate native species in competition, augmenting other potential advantages such as release from natural enemies. Resource pre-emption may be a particularly important mechanism for establishing dominance over competitors of the same functional type. We hypothesized that competitive success of an exotic grass against native grasses is mediated by establishing an early size advantage. We tested this prediction among four perennial C4 warm-season grasses: the exotic weed Johnsongrass (Sorghum halepense), big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparius) and switchgrass (Panicum virgatum). We predicted that a) the competitive effect of Johnsongrass on target species would be proportional to their initial biomass difference, b) competitive effect and response would be negatively correlated and c) soil fertility would have little effect on competitive relationships. In a greenhouse, plants of the four species were grown from seed either alone or with one Johnsongrass neighbor at two fertilizer levels and periodically harvested. The first two hypotheses were supported: The seedling biomass of single plants at first harvest (50 days after seeding) ranked the same way as the competitive effect of Johnsongrass on target species: Johnsongrass < big bluestem < little bluestem/switchgrass, while Johnsongrass responded more strongly to competition from Johnsongrass than from native species. At final harvest, native plants growing with Johnsongrass attained between 2–5% of their single-plant non-root biomass, while Johnsongrass growing with native species attained 89% of single-plant non-root biomass. Fertilization enhanced Johnsongrass’ competitive effects on native species, but added little to the already severe competitive suppression. Accelerated early growth of Johnsongrass seedlings relative to native seedlings appeared to enable subsequent resource pre-emption. Size-asymmetric competition and resource-pre-emption may be a critical mechanism by which exotic invasive species displace functionally similar native species and alter the functional dynamics of native communities. PMID:28467488

Accelerated development in Johnsongrass seedlings (Sorghum halepense) suppresses the growth of native grasses through size-asymmetric competition.

PubMed

Schwinning, Susanne; Meckel, Heather; Reichmann, Lara G; Polley, H Wayne; Fay, Philip A

2017-01-01

Invasive plant species often dominate native species in competition, augmenting other potential advantages such as release from natural enemies. Resource pre-emption may be a particularly important mechanism for establishing dominance over competitors of the same functional type. We hypothesized that competitive success of an exotic grass against native grasses is mediated by establishing an early size advantage. We tested this prediction among four perennial C4 warm-season grasses: the exotic weed Johnsongrass (Sorghum halepense), big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparius) and switchgrass (Panicum virgatum). We predicted that a) the competitive effect of Johnsongrass on target species would be proportional to their initial biomass difference, b) competitive effect and response would be negatively correlated and c) soil fertility would have little effect on competitive relationships. In a greenhouse, plants of the four species were grown from seed either alone or with one Johnsongrass neighbor at two fertilizer levels and periodically harvested. The first two hypotheses were supported: The seedling biomass of single plants at first harvest (50 days after seeding) ranked the same way as the competitive effect of Johnsongrass on target species: Johnsongrass < big bluestem < little bluestem/switchgrass, while Johnsongrass responded more strongly to competition from Johnsongrass than from native species. At final harvest, native plants growing with Johnsongrass attained between 2-5% of their single-plant non-root biomass, while Johnsongrass growing with native species attained 89% of single-plant non-root biomass. Fertilization enhanced Johnsongrass' competitive effects on native species, but added little to the already severe competitive suppression. Accelerated early growth of Johnsongrass seedlings relative to native seedlings appeared to enable subsequent resource pre-emption. Size-asymmetric competition and resource-pre-emption may be a critical mechanism by which exotic invasive species displace functionally similar native species and alter the functional dynamics of native communities.

Growth response of four species of Eastern hardwood tree seedlings exposed to ozone, acidic precipitation, and sulfur dioxide. [Prunus serotina, Acer rubrum, Quercus rubra, Liriodendron tulipifera

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, D.D. Skelly, J.M.

1992-03-01

In 1987 a study was conducted in controlled environment chambers to determine the foliar sensitivity of tree seedlings of eight species to ozone and acidic precipitation, and to determine the influence of leaf position on symptom severity. Jensen and Dochinger conducted concurrent similar studies in Continuously Stirred Tank Reactor (CSTR) chambers with ten species of forest trees. Based on the results of these initial studies, four species representing a range in foliar sensitivity to ozone were chosen: black cherry (Prunus serotina Ehrh.), red maple (Acer rubrum L.), northern red oak (Quercus rubra L.) and yellow-poplar (Liriodendron tulipifera L.). These speciesmore » were also chosen because of their ecological and/or commercial importance in Pennsylvania. Seedlings were exposed in growth chambers simulated acid rain. In addition acute exposures to sulfur dioxide were conducted in a regime based on unpublished monitoring data collected near coal-fired power plants. The objective of this study was to determine if the pollutant treatments influenced the growth and productivity of seedlings of these four species. This information will help researchers and foresters understand the role of air pollution in productivity of eastern forests.« less

HYPOTrace: image analysis software for measuring hypocotyl growth and shape demonstrated on Arabidopsis seedlings undergoing photomorphogenesis.

PubMed

Wang, Liya; Uilecan, Ioan Vlad; Assadi, Amir H; Kozmik, Christine A; Spalding, Edgar P

2009-04-01

Analysis of time series of images can quantify plant growth and development, including the effects of genetic mutations (phenotypes) that give information about gene function. Here is demonstrated a software application named HYPOTrace that automatically extracts growth and shape information from electronic gray-scale images of Arabidopsis (Arabidopsis thaliana) seedlings. Key to the method is the iterative application of adaptive local principal components analysis to extract a set of ordered midline points (medial axis) from images of the seedling hypocotyl. Pixel intensity is weighted to avoid the medial axis being diverted by the cotyledons in areas where the two come in contact. An intensity feature useful for terminating the midline at the hypocotyl apex was isolated in each image by subtracting the baseline with a robust local regression algorithm. Applying the algorithm to time series of images of Arabidopsis seedlings responding to light resulted in automatic quantification of hypocotyl growth rate, apical hook opening, and phototropic bending with high spatiotemporal resolution. These functions are demonstrated here on wild-type, cryptochrome1, and phototropin1 seedlings for the purpose of showing that HYPOTrace generated expected results and to show how much richer the machine-vision description is compared to methods more typical in plant biology. HYPOTrace is expected to benefit seedling development research, particularly in the photomorphogenesis field, by replacing many tedious, error-prone manual measurements with a precise, largely automated computational tool.

An endogenous growth pattern of roots is revealed in seedlings grown in microgravity.

PubMed

Millar, Katherine D L; Johnson, Christina M; Edelmann, Richard E; Kiss, John Z

2011-10-01

In plants, sensitive and selective mechanisms have evolved to perceive and respond to light and gravity. We investigated the effects of microgravity on the growth and development of Arabidopsis thaliana (ecotype Landsberg) in a spaceflight experiment. These studies were performed with the Biological Research in Canisters (BRIC) hardware system in the middeck region of the space shuttle during mission STS-131 in April 2010. Seedlings were grown on nutrient agar in Petri dishes in BRIC hardware under dark conditions and then fixed in flight with paraformaldehyde, glutaraldehyde, or RNAlater. Although the long-term objective was to study the role of the actin cytoskeleton in gravity perception, in this article we focus on the analysis of morphology of seedlings that developed in microgravity. While previous spaceflight studies noted deleterious morphological effects due to the accumulation of ethylene gas, no such effects were observed in seedlings grown with the BRIC system. Seed germination was 89% in the spaceflight experiment and 91% in the ground control, and seedlings grew equally well in both conditions. However, roots of space-grown seedlings exhibited a significant difference (compared to the ground controls) in overall growth patterns in that they skewed to one direction. In addition, a greater number of adventitious roots formed from the axis of the hypocotyls in the flight-grown plants. Our hypothesis is that an endogenous response in plants causes the roots to skew and that this default growth response is largely masked by the normal 1 g conditions on Earth.

Relative Fusiform Rust Resistance of Loblolly and Slash Pine Sources and Families in Georgia and South Carolina

Treesearch

E. George Kuhlman; Harry R. Powers; William D. Pepper

1995-01-01

Loblolly and slash pine seedlings from the fusiform rust resistant orchards developed cooperatively by the USDA Forest Service and the Georgia Forestry Commission had significantly less rust 7 to 8 years after planting on four of five sites in the Southeastern United States than seedlings of the same species from orchard sources developed primarily for silvicultural...

Lead mobility within the xylem of red spruce seedlings: Implications for the development of pollution histories

Treesearch

John R. Donnelly; John B. Shane; Paul G. Schaberg

1990-01-01

Development of Pb pollution histories using tree ring analyses has been troubled by possible mobility of Pb within stem xylem. In a 2-yr study, we exposed red spruce (Picea rubens Sarg.) seedlings to Pb during one growing season, with Pb excluded in either the previous or following growing season. Lead levels within xylem rings and bark were...

A comparison of the survival and development of the seedlings of four upland oak species grown in four different understory light environments

Treesearch

Patrick Brose; Joanne Rebbeck

2017-01-01

Oak (Quercus spp.) research and management often focus on northern red oak (Quercus rubra) and assume that associated upland oaks have similar growth patterns. To test this premise, we measured the survival and development of four species of acorn-origin oak seedlings growing in four different levels of understory sunlight for...

Effects of seed production, seedbed condition, and overstory basal area on the establishment of shortleaf pine seedlings in the Ouachita Mountains

Treesearch

Michael G. Shelton

1995-01-01

Some of the factors affecting the establishment of shortleaf pine regeneration after the initial treatments implementing uneven-aged silviculture in shortleaf pine-hardwood stands are quantitatively described in this publication.

Extensive variation, but not local adaptation in an Australian alpine daisy.

PubMed

Hirst, Megan J; Sexton, Jason P; Hoffmann, Ary A

2016-08-01

Alpine plants often occupy diverse habitats within a similar elevation range, but most research on local adaptation in these plants has focused on elevation gradients. In testing for habitat-related local adaptation, local effects on seed quality and initial plant growth should be considered in designs that encompass multiple populations and habitats. We tested for local adaptation across alpine habitats in a morphologically variable daisy species, Brachyscome decipiens, in the Bogong High Plains in Victoria, Australia. We collected seed from different habitats, controlled for maternal effects through initial seed size estimates, and characterized seedling survival and growth in a field transplant experiment. We found little evidence for local adaptation for survival or plant size, based on three adaptation measures: Home versus Away, Local versus Foreign, and Sympatric versus Allopatric (SA). The SA measure controlled for planting site and population (site-of-origin) effects. There were significant differences due to site-of-origin and planting site effects. An important confounding factor was the size of plants directly after transplantation of seedlings, which had a large impact on subsequent seedling survival and growth. Initial differences in plant width and height influenced subsequent survival across the growing season but in opposing directions: wide plants had higher survival, but tall plants had lower survival. In an additional controlled garden experiment at Cranbourne Royal Botanic Gardens, site-of-origin effects detected in the field experiments disappeared under more benign homogeneous conditions. Although B. decipiens from different source areas varied significantly when grown across a range of alpine habitats, these differences did not translate into a local or habitat-related fitness advantage. This lack of local advantage may signal weak past selection, and/or weak adaptive transgeneration (plasticity) effects.

Predicting field weed emergence with empirical models and soft computing techniques

USDA-ARS?s Scientific Manuscript database

Seedling emergence is the most important phenological process that influences the success of weed species; therefore, predicting weed emergence timing plays a critical role in scheduling weed management measures. Important efforts have been made in the attempt to develop models to predict seedling e...

Volatiles associated with preferred and nonpreferred hosts of the nantucket pine tip moth, Rhyacionia frustrana

Treesearch

Christopher Asaro; Brian T. Sullivan; M.J. Dalusky; C. Wayne Berisford

2004-01-01

Ovipositing female Nantucket pine tip moth, Rhyacionia frustrana, prefer loblolly pine, Pinus taeda L., to slash pine, Pinus elliottii Englem. except during the first spring following planting of seedlings. Host discrimination by R. frustrana increases as seedlings develop, suggesting that...

Electromagnetic Treatment of Loblolly Pine Seeds

Treesearch

James P. Barnett; Stanley L. Krugman

1989-01-01

Loblolly pine (Pinus taeda L.) seeds were exposed to an electromagnetic radiation treatment (Energy Transfer Process, marketed by the Energy Transfer Corporation), and the effects of the treatments on seed germination, seedling development, disease resistance, and field performance of seedlings were evaluated. None of the evaluated variables showed...

Dissecting cold tolerance in rice as revealed by association mapping

USDA-ARS?s Scientific Manuscript database

Cold stress is an important abiotic stress which negatively affects morphological development and seed production in rice (Oryza sativa L.). At the seedling stage, cold stress causes poor germination, seedling injury and poor stand establishment; and at the reproductive stage cold decreases seed yi...

Carlactone-independent seedling morphogenesis in Arabidopsis.

PubMed

Scaffidi, Adrian; Waters, Mark T; Ghisalberti, Emilio L; Dixon, Kingsley W; Flematti, Gavin R; Smith, Steven M

2013-10-01

Strigolactone hormones are derived from carotenoids via carlactone, and act through the α/β-hydrolase D14 and the F-box protein D3/MAX2 to repress plant shoot branching. While MAX2 is also necessary for normal seedling development, D14 and the known strigolactone biosynthesis genes are not, raising the question of whether endogenous, canonical strigolactones derived from carlactone have a role in seedling morphogenesis. Here, we report the chemical synthesis of the strigolactone precursor carlactone, and show that it represses Arabidopsis shoot branching and influences leaf morphogenesis via a mechanism that is dependent on the cytochrome P450 MAX1. In contrast, both physiologically active Z-carlactone and the non-physiological E isomer exhibit similar weak activity in seedlings, and predominantly signal through D14 rather than its paralogue KAI2, in a MAX2-dependent but MAX1-independent manner. KAI2 is essential for seedling morphogenesis, and hence this early-stage development employs carlactone-independent morphogens for which karrikins from wildfire smoke are specific surrogates. While the commonly employed synthetic strigolactone GR24 acts non-specifically through both D14 and KAI2, carlactone is a specific effector of strigolactone signalling that acts through MAX1 and D14. © 2013 The Authors The Plant Journal © 2013 John Wiley & Sons Ltd.

Genome-wide association analysis of seedling root development in maize (Zea mays L.).

PubMed

Pace, Jordon; Gardner, Candice; Romay, Cinta; Ganapathysubramanian, Baskar; Lübberstedt, Thomas

2015-02-05

Plants rely on the root system for anchorage to the ground and the acquisition and absorption of nutrients critical to sustaining productivity. A genome wide association analysis enables one to analyze allelic diversity of complex traits and identify superior alleles. 384 inbred lines from the Ames panel were genotyped with 681,257 single nucleotide polymorphism markers using Genotyping-by-Sequencing technology and 22 seedling root architecture traits were phenotyped. Utilizing both a general linear model and mixed linear model, a GWAS study was conducted identifying 268 marker trait associations (p ≤ 5.3×10(-7)). Analysis of significant SNP markers for multiple traits showed that several were located within gene models with some SNP markers localized within regions of previously identified root quantitative trait loci. Gene model GRMZM2G153722 located on chromosome 4 contained nine significant markers. This predicted gene is expressed in roots and shoots. This study identifies putatively associated SNP markers associated with root traits at the seedling stage. Some SNPs were located within or near (<1 kb) gene models. These gene models identify possible candidate genes involved in root development at the seedling stage. These and respective linked or functional markers could be targets for breeders for marker assisted selection of seedling root traits.

Buds enable pitch and shortleaf pines to recover from injury

Treesearch

S. Little; H. A. Somes

1956-01-01

Pitch and shortleaf pines often survive severe damage by fires, cutting, rabbits, or deer. Deer may take all but 2 inches of the 6- to 8-inch shoots of seedlings, and still these seedlings may live and develop new shoots. Fires may kill all the foliage and terminal shoots on sapling or pole-size stems, but still these trees may green up and develop new leaders. Many of...

Effects of the Forest Floor and Acorn Placement on Establishment and Early Development of Water Oak Seedlings

Treesearch

Yanfei Guo; Michael G. Shelton; B.R. Lockhart

1999-01-01

Effects of the forest floor (0, 10, 20, 30,40, and 50 Mg/ha) and acorn placement (buried 1.5 cm below the soil surface, pressed into the soil surface, and placed within the forest floor) on establishment and early development of water oak (Quercus nigra L.) seedlings were tested in a 6 x 3 factorial study in southeastern Arkansas. Increasing...

Damage repair effect of He-Ne laser on wheat exposed to enhanced ultraviolet-B radiation.

PubMed

Yang, Liyan; Han, Rong; Sun, Yi

2012-08-01

We explored the use of He-Ne laser on alleviating the effects of ultraviolet-B (UV-B) light on winter wheat development. Triticum aestivum L. cv. Linyuan 077038 seeds were irradiated with either UV-B (10.08 kJ m(-2) d(-1)) (enhanced UV-B) or a combination of UV-B light and the He-Ne laser (5.43 mW mm(-2)). Plants also were exposed to the He-Ne laser alone. Our results showed that enhanced UV-B produced negative effects on seed germination and seedling development. Germination rate and shoot growth decreased compared with the control. Root development was inhibited, and root length was decreased. Chlorophyll content and expression of peroxidase (POD) isozymes and their activity decreased. Seedling height and shoot biomass dropped significantly compared to the control. Implementing the He-Ne laser partially alleviated the injury of enhanced UV-B radiation, because germination rate and shoot growth were enhanced together with root development. Chlorophyll content and POD expression and activity increased. Seedling height and shoot biomass were increased. Furthermore, the use of the He-Ne laser alone showed a favorable effect on seedling growth compared with the control. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Improvement of the zygote utilization and reduction of the seedling loss in the early stage of seedling production of Sargassum thunbergii (Fucales, Phaeophyta)

NASA Astrophysics Data System (ADS)

Liu, Wei; Wu, Haiyi; Liu, Mengxia; Duan, Delin

2016-05-01

Artificial seedling production of Sargassum thunbergii is an effective way to relieve pressure on natural resources. In order to improve the utilization of zygotes and reduce the loss of seedlings, studies on the characteristic of the zygotes release, the development of rhizoids, the attachment of germlings, and the influence of jet washing were conducted. Results show that the percent of zygotes released was increased with time in the first 60 h. The capacity of germlings attached to the substratum was significantly increased, especially coincident with the time of the new rhizoids emerged and elongated. The detachment rate of germlings significantly decreased with the delay of starting time of jet washing or the reduction of jet washing velocity. However, the jet washing at any level applied in the experiment could cause considerable loss of germlings within the 20 days after the attachment. Our study provided some parameters to optimize the operation in the early stage of seedling production.

The parasitic plant Cuscuta australis is highly insensitive to abscisic acid-induced suppression of hypocotyl elongation and seed germination.

PubMed

Li, Juan; Hettenhausen, Christian; Sun, Guiling; Zhuang, Huifu; Li, Jian-Hong; Wu, Jianqiang

2015-01-01

Around 1% of angiosperms are parasitic plants. Their growth and development solely or partly depend on host plants from which they extract water, nutrients, and other molecules using a parasitic plant-specific organ, the haustorium. Strong depletion of nutrients can result in serious growth retardation and in some cases, death of the hosts. The genus Cuscuta (dodder) comprises about 200 holoparasitic species occurring on all continents. Their seedlings have no roots and cotyledons but are only string-like hypocotyls. When they contact suitable host plants, haustoria are formed and thereafter seedlings rapidly develop into vigorously growing branches without roots and leaves. This highly specialized lifestyle suggests that Cuscuta plants likely have unique physiology in development and stress responses. Using germination and seedling growth assays, we show that C. australis seeds and seedlings are highly insensitive to abscisic acid (ABA). Transcriptome analysis and protein sequence alignment with Arabidopsis, tomato, and rice homologs revealed that C. australis most likely consists of only four functional ABA receptors. Given that Cuscuta plants are no longer severely challenged by drought stress, we hypothesize that the ABA-mediated drought resistance pathway in Cuscuta spp. might have had degenerated over time during evolution.

Overexpression of a Medicago truncatula stress-associated protein gene (MtSAP1) leads to nitric oxide accumulation and confers osmotic and salt stress tolerance in transgenic tobacco.

PubMed

Charrier, Aurélie; Planchet, Elisabeth; Cerveau, Delphine; Gimeno-Gilles, Christine; Verdu, Isabelle; Limami, Anis M; Lelièvre, Eric

2012-08-01

The impact of Medicago truncatula stress-associated protein gene (MtSAP1) overexpression has been investigated in Nicotiana tabacum transgenic seedlings. Under optimal conditions, transgenic lines overexpressing MtSAP1 revealed better plant development and higher chlorophyll content as compared to wild type seedlings. Interestingly, transgenic lines showed a stronger accumulation of nitric oxide (NO), a signaling molecule involved in growth and development processes. This NO production seemed to be partially nitrate reductase dependent. Due to the fact that NO has been also reported to play a role in tolerance acquisition of plants to abiotic stresses, the responses of MtSAP1 overexpressors to osmotic and salt stress have been studied. Compared to the wild type, transgenic lines were less affected in their growth and development. Moreover, NO content in MtSAP1 overexpressors was always higher than that detected in wild seedlings under stress conditions. It seems that this better tolerance induced by MtSAP1 overexpression could be associated with this higher NO production that would enable seedlings to reach a high protection level to prepare them to cope with abiotic stresses.

Genetic Architecture of Cold Tolerance in Rice (Oryza sativa) Determined through High Resolution Genome-Wide Analysis

USDA-ARS?s Scientific Manuscript database

Cold temperature is an important abiotic stress which negatively affects morphological development and seed production in rice (Oryza sativa L.). At the seedling stage, cold stress causes poor germination, seedling injury and poor stand establishment; and at the reproductive stage cold decreases se...

Toward a single nursery protocol for oak seedlings

Treesearch

Paul P. Kormanik; Shi-Jean S. Sung; T.L. Kormanik

1994-01-01

After a soil fertility baseline had been determined for the Georgia Forestry Commission's (GFC) Morgan Nursery, and single nursery protocol consistently produced high quality oak seedlings. The fertility baseline developed at the Institute of Tree Root Biology's Whitehall Experimental Nursery and adjusted for three GFC nurseries has a background target level...

A comparative study between nonlinear regression and nonparametric approaches for modelling Phalaris paradoxa seedling emergence

USDA-ARS?s Scientific Manuscript database

Parametric non-linear regression (PNR) techniques commonly are used to develop weed seedling emergence models. Such techniques, however, require statistical assumptions that are difficult to meet. To examine and overcome these limitations, we compared PNR with a nonparametric estimation technique. F...

Establishing big sagebrush and other shrubs from planting stock

Treesearch

Nancy L. Shaw; Anne Halford; J. Kent McAdoo

2015-01-01

Bareroot or container seedlings can be used to quickly re-establish big sagebrush and other native shrubs in situations where direct seeding is not feasible or unlikely to succeed. Guidelines are provided for developing a planting plan and timeline, arranging for seedling production, and installing and managing outplantings.

Seed deposition patterns and the survival of seeds and seedlings of the palm Euterpe edulis

NASA Astrophysics Data System (ADS)

Pizo, Marco A.; Simão, Isaac

2001-08-01

The seed deposition pattern created by a seed disperser is one of the components of the efficiency of a species as seed disperser, and ultimately may influence the recruitment of a plant species. In this study, we used the seeds of a bird-dispersed forest palm, Euterpe edulis, to investigate the effects of two distinct seed deposition patterns created by birds that defecate (clumped pattern) and regurgitate seeds (loose-clumped pattern) on the survival of seeds experimentally set in an E. edulis-rich site, and of seedlings grown under shade-house conditions. The study was conducted in the lowland forest of Parque Estadual Intervales, SE Brazil. Clumped and loose-clumped seeds were equally preyed upon by rodents and insects. Although clumped and isolated seedlings had the same root weight after 1 year, the isolated seedlings survived better and presented more developed shoots, suggesting intraspecific competition among clumped seedlings. Our results indicate that animals that deposit E. edulis seeds in faecal clumps (e.g. cracids, tapirs) are less efficient seed dispersers than those that regurgitate seeds individually (e.g. trogons, toucans). Intraspecific competition among seedlings growing from faecal clumps is a likely process preventing the occurrence of clumps of adult palms.

Toxic effect of perfluorooctanoic acid (PFOA) on germination and seedling growth of wheat (Triticum aestivum L.).

PubMed

Zhou, Lina; Xia, Mengjie; Wang, Li; Mao, Hui

2016-09-01

As a persistent organic pollutant in the environment, perfluorooctanoic acid (PFOA) has been extensively investigated. It can accumulate in food chains and in the human body. This work investigated the effect of PFOA on wheat (Triticum aestivum L.) germination and seedling growth by conducting a germination trial and a pot trial. A stimulatory effect of PFOA on seedling growth and root length of wheat was found at <0.2 mg kg(-1), while >800 mg kg(-1) PFOA inhibited germination rate, index, and root and shoot growth. In the pot trial, PFOA concentration in root was double that in the shoot. Soil and plant analyzer development (SPAD) and plant height of wheat seedling were inhibited by adding 200 mg kg(-1) PFOA. Proline content and POD activity in wheat seedlings increased as PFOA increased, while CAT activity decreased. Using logarithmic equations, proline content was selected as the most sensitive index by concentration for 50% of maximal effect (EC50). Hence, the tolerance of wheat seedlings to PFOA levels could be evaluated on the basis of the physiological index. Copyright © 2016 Elsevier Ltd. All rights reserved.

The effectiveness of surface liming in ameliorating the phytotoxic effects of soil contaminated by copper acid leach pad solution in an arid ecosystem

NASA Astrophysics Data System (ADS)

Golos, Peter

2016-04-01

Revegetation of sites following soil contamination can be challenging especially in identifying the most effective method for ameliorating phytotoxic effects in arid ecosystems. This study at a copper mine in the Great Sandy Desert of Western Australia investigated vegetation restoration of a site contaminated by acid (H2SO4) leach pad solution. Elevated soil copper at low soil pH is phytotoxic to plant roots inhibiting root elongation. In arid ecosystems where rapid root growth is crucial for seedling survival post germination physical or chemical barriers to root growth need to be identified and ameliorated. Initial attempt at rehabilitation of contaminated site with hydrated lime (CaOH2) at 2 tonnes/ha followed by ripping to 30 cm depth then seeding was ineffective as successful seedling emergence was followed by over 90% seedling mortality which was 10-fold greater than seedling mortality in an uncontaminated reference site. High mortality was attributed to seedling roots being impededed as soil water was more than 3-fold greater at 5 to 40 cm depth in contaminated site than reference site. In response to high seedling mortality after emergence test pits were dug to 1 m deep to collect soil samples at 10 cm intervals for phytotoxicity testing and to measure soil pH-CaCl2, copper (DPTA ion extraction), electrical conductivity and gravimetric water content in three replicate pits at three replicate sites. Also, soil impedance was measured down the soil profile at 5 cm intervals at six replicate points/pit. For phytotoxicity testing soil samples were placed into three replicate plastic pots/sample and seeded with 10 seeds of Avena sativa and watered daily. Seedlings were harvested after at least two weeks after seedling emergence and rooting depth in pots measured. There was no difference in seedling emergence and survival of seedlings between contaminated and uncontaminated soil samples however mean seedling root growth was significantly lower in soil samples collected at >10 cm depth than the control. Mean soil pH at 0-10 cm was higher (>7.2) at all sites treated with lime compared to uncontaminated soil (5.5). At depths greater than 10 cm soil pH was <4.6. Soil copper was >16 mg/kg in all contaminated soil samples compared to 0.5 mg/kg in control. High seedling mortality in contaminated site is attributed to low soil pH and elevated soil copper levels which inhibited plant root growth and hence access to soil water. While surface liming of soil increased soil pH ameliorating the effect of elevated soil copper, this was only effective in the top 10 cm due to low solubility of hydrated lime. To improve seedling survival lime will need to be incorporated into the contaminated soil profile to allow plants to access soil water at depth. This study highlights the importance of the need to assess the phytotoxic effects of soil contamination and the effectiveness of amelioration treatments and with proper reference to its ecological context. To improve the success of vegetation restoration of sites contaminated with acidic copper solution, lime needs to be incorporated into the contaminated soil profile to allow plant roots to access soil water at depth. This study highlights the importance of the need to assess the phytotoxic effects of soil contamination and the effectiveness of amelioration treatments and with proper reference to its ecological context.

Gene Expression in Plant Lipid Metabolism in Arabidopsis Seedlings

PubMed Central

Hsiao, An-Shan; Haslam, Richard P.; Michaelson, Louise V.; Liao, Pan; Napier, Johnathan A.; Chye, Mee-Len

2014-01-01

Events in plant lipid metabolism are important during seedling establishment. As it has not been experimentally verified whether lipid metabolism in 2- and 5-day-old Arabidopsis thaliana seedlings is diurnally-controlled, quantitative real-time PCR analysis was used to investigate the expression of target genes in acyl-lipid transfer, β-oxidation and triacylglycerol (TAG) synthesis and hydrolysis in wild-type Arabidopsis WS and Col-0. In both WS and Col-0, ACYL-COA-BINDING PROTEIN3 (ACBP3), DIACYLGLYCEROL ACYLTRANSFERASE1 (DGAT1) and DGAT3 showed diurnal control in 2- and 5-day-old seedlings. Also, COMATOSE (CTS) was diurnally regulated in 2-day-old seedlings and LONG-CHAIN ACYL-COA SYNTHETASE6 (LACS6) in 5-day-old seedlings in both WS and Col-0. Subsequently, the effect of CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY) from the core clock system was examined using the cca1lhy mutant and CCA1-overexpressing (CCA1-OX) lines versus wild-type WS and Col-0, respectively. Results revealed differential gene expression in lipid metabolism between 2- and 5-day-old mutant and wild-type WS seedlings, as well as between CCA1-OX and wild-type Col-0. Of the ACBPs, ACBP3 displayed the most significant changes between cca1lhy and WS and between CCA1-OX and Col-0, consistent with previous reports that ACBP3 is greatly affected by light/dark cycling. Evidence of oil body retention in 4- and 5-day-old seedlings of the cca1lhy mutant in comparison to WS indicated the effect of cca1lhy on storage lipid reserve mobilization. Lipid profiling revealed differences in primary lipid metabolism, namely in TAG, fatty acid methyl ester and acyl-CoA contents amongst cca1lhy, CCA1-OX, and wild-type seedlings. Taken together, this study demonstrates that lipid metabolism is subject to diurnal regulation in the early stages of seedling development in Arabidopsis. PMID:25264899

Rapid photosynthetic acclimation of Shorea johorensis seedlings after logging disturbance in Central Kalimantan.

PubMed

Clearwater, M J; Susilawaty, R; Effendi, R; van Gardingen, P R

1999-12-01

This study examined the photosynthetic acclimation of pre-existing Shorea johorensis (Dipterocarpaceae) seedlings to the change in conditions that occurs at the time of logging in Central Kalimantan, Indonesia. The hypothesis was that the seedlings would be unable to acclimate beyond partially open conditions after canopy disturbance caused by logging, therefore limiting the potential for regeneration in the most open areas. Bleaching and reductions in the predawn ratio of variable to maximum fluorescence (F v /F m ) indicated chronic photoinhibition and damage to the previously shade-adapted leaves of seedlings in an area logged 2 weeks earlier. The majority of seedlings in partially open and open environments of an area logged 3 months earlier were already growing fast. Leaves that had developed in the new environment showed only small reductions in predawn F v /F m and large increases in the light saturated rate of photosynthesis (A max ) per unit area when compared to shaded seedlings. Leaves in the most open environments had higher but more variable nitrogen concentrations, A max per unit area and A max per unit mass when compared to seedlings in partially open environments. Increases in dark respiration were disproportionately large compared to increases in A max , and may have been the result of increased investment in photoprotective mechanisms. The response of stomatal conductance to the vapour pressure deficit and leaf temperature was examined, but it suggested only a 10% reduction in daily leaf level carbon gain in open environments. The ratio of leaf area to fine root mass was highest in shade-suppressed and newly exposed seedlings, suggesting a potential hydraulic limitation to transpiration during acclimation. However, rainfall during this period was high and leaf water potentials did not differ between disturbed and undisturbed environments. S. johorensis seedlings were capable of significant acclimation to conditions more extreme than partial canopy opening. Low seedling density after logging during the wet season cannot be explained by a limited potential for photosynthetic acclimation.

Resource availability and repeated defoliation mediate compensatory growth in trembling aspen (Populus tremuloides) seedlings

PubMed Central

Galvez, David A.; Zhang, Bin; Najar, Ahmed

2014-01-01

Plant ecologists have debated the mechanisms used by plants to cope with the impact of herbivore damage. While plant resistance mechanisms have received much attention, plant compensatory growth as a type of plant tolerance mechanisms has been less studied. We conducted a greenhouse experiment to evaluate compensatory growth for trembling aspen (Populus tremuloides) seedlings under varying intensities and frequencies of simulated defoliation, with or without nutrient enriched media. For the purpose of this study, changes in biomass production and non-structural carbohydrate concentrations (NSC) of roots and leaves were considered compensatory responses. All defoliated seedlings showed biomass accumulation under low defoliation intensity and frequency, regardless of resource availability; however, as defoliation intensity and frequency increased, compensatory growth of seedlings was altered depending on resource availability. Seedlings in a resource-rich environment showed complete compensation, in contrast responses ranged from undercompensation to complete compensation in a resource-limited environment. Furthermore, at the highest defoliation intensity and frequency, NSC concentrations in leaves and roots were similar between defoliated and non-defoliated seedlings in a resource-rich environment; in contrast, defoliated seedlings with limited resources sustained the most biomass loss, had lower amounts of stored NSC. Using these results, we developed a new predictive framework incorporating the interactions between frequency and intensity of defoliation and resource availability as modulators of plant compensatory responses. PMID:25083352

Phenylalanine derived cyanogenic diglucosides from Eucalyptus camphora and their abundances in relation to ontogeny and tissue type.

PubMed

Neilson, Elizabeth H; Goodger, Jason Q D; Motawia, Mohammed Saddik; Bjarnholt, Nanna; Frisch, Tina; Olsen, Carl Erik; Møller, Birger Lindberg; Woodrow, Ian E

2011-12-01

The cyanogenic glucoside profile of Eucalyptus camphora was investigated in the course of plant ontogeny. In addition to amygdalin, three phenylalanine-derived cyanogenic diglucosides characterized by unique linkage positions between the two glucose moieties were identified in E. camphora tissues. This is the first time that multiple cyanogenic diglucosides have been shown to co-occur in any plant species. Two of these cyanogenic glucosides have not previously been reported and are named eucalyptosin B and eucalyptosin C. Quantitative and qualitative differences in total cyanogenic glucoside content were observed across different stages of whole plant and tissue ontogeny, as well as within different tissue types. Seedlings of E. camphora produce only the cyanogenic monoglucoside prunasin, and genetically based variation was observed in the age at which seedlings initiate prunasin biosynthesis. Once initiated, total cyanogenic glucoside concentration increased throughout plant ontogeny with cyanogenic diglucoside production initiated in saplings and reaching a maximum in flower buds of adult trees. The role of multiple cyanogenic glucosides in E. camphora is unknown, but may include enhanced plant defense and/or a primary role in nitrogen storage and transport. Copyright © 2011 Elsevier Ltd. All rights reserved.

The effect of ectomycorrhizal fungi forming symbiosis with Pinus pinaster seedlings exposed to cadmium.

PubMed

Sousa, Nadine R; Ramos, Miguel A; Marques, Ana P G C; Castro, Paula M L

2012-01-01

Cadmium is one of the most toxic heavy metals and its accumulation in the upper layers of forest soils affects plants, microorganisms and their interactions. Adequate strategies for the reforestation of metal contaminated sites are of vital importance. The aim of this work was to evaluate the response of Pinus pinaster seedlings to Cd exposure and to assess the effect of inoculation with two selected ectomycorrhizal fungi, Suillus bovinus and Rhizopogon roseolus on that response. Seedlings were exposed to soil contaminated at 15 and 30 mg Cd kg(-1). Shoot biomass of P. pinaster decreased ca. 36% when exposed to 15 mg Cd kg(-1). Overall, colonization by S. bovinus significantly enhanced shoot development up to 30% in contaminated soil while colonization by R. roseolus produced no significant effect at both Cd concentrations tested and significantly increased the level of Cd in the shoots at both Cd concentrations. Metal accumulation in the shoots and roots of non-inoculated and S. bovinus-inoculated seedlings increased at the higher Cd levels whereas R. roseolus-inoculated seedlings were not sensitive to Cd variation in the soil. The results from our research show that inoculation with ECM fungi has a significant impact on metal uptake and development of P. pinaster seedlings; the differential response induced by the two tested species highlights the importance of selecting the appropriate strains for nursery inoculation, and, as such, this biological tool ought to be considered in reforestation processes of heavy metal contaminated areas by woody species. Copyright © 2011 Elsevier B.V. All rights reserved.

Weak Evidence of Regeneration Habitat but Strong Evidence of Regeneration Niche for a Leguminous Shrub

PubMed Central

Delerue, Florian; Gonzalez, Maya; Michalet, Richard; Pellerin, Sylvain; Augusto, Laurent

2015-01-01

The identification of an ecological niche specific to the regeneration phase has mobilised significant attention. However, the importance of the regeneration niche concept remains unclear. Our main objective was to study the existence of such a regeneration niche for a leguminous shrub, Ulex europaeus. This study was carried out in southwest France in the context of water and nutrient stresses (mainly phosphorus limitation) due to the presence of nutrient-poor sandy soils. We analysed the regeneration of the species from the germination of seeds and emergence of new seedlings until the seedlings reached young shrub size. Our design included a P fertilisation treatment. We also investigated microsite characteristics (micro-topography and vegetation development) as they can interact with meteorological conditions and determine water availability for seeds and seedlings. We found that P availability controlled seedling growth and the time necessary to reach young shrub size. Water availability appeared to impact the species germination and seedlings survival. We also found that P and water availability depended on the interactions between microsite characteristics and climatic variations. Finally we found evidence that P and water availability are important ecological factors shaping the regeneration niche of the species, but we found weak evidence that any microsite would be appropriate for the regeneration of the species in the long term. Future studies regarding regeneration niches need to distinguish more clearly the ecological factors important for regeneration (the regeneration niche per se) and the physical world where the seedlings appear and develop (the regeneration habitat). PMID:26098877

Africa's Great Green Wall Initiative: a model for restoration success

NASA Astrophysics Data System (ADS)

Berrahmouni, Nora; Sacande, Moctar

2014-05-01

The Great Green Wall for the Sahara and the Sahel Initiative was launched to address the increasing challenges of land degradation, desertification and drought, climate change, food insecurity and poverty in more than 20 countries. Restoration of agro-sylvo-pastoral landscapes and degraded lands is one of the priority interventions initiated, enabling the springing up of green nests of life. When complete, the Great Green Wall of Africa will reverse the seemingly unstoppable desertification and address the development of its drylands' inhabitant rural communities. Today's planting of modest seedlings will grow into vast mosaics of forest and agroforestry landscapes and grasslands, which will provide essential ecosystem goods and services, restore lost livelihoods and create new wealth. The ambition of reforestation efforts within this initiative - the like of which the world has never seen before - sounds like an impossible dream. However, learning from past mistakes and capitalising on current advancement in science and technology, it is a reality that is taking root. Following a successful restoration model that RBG Kew experts have devised, we are helping to mobilise, train and support communities in four border regions in Burkina Faso, Mali and Niger. In collaboration with FAO, the Millennium Seed Bank Partnership is using its unique expertise to ensure that seeds of environmentally well-adapted and economically useful local species are collected and planted in communal gardens and village agroforestry systems managed by the communities themselves. In our first year, an estimated total of 162,000 seedlings and 61 kg of seeds from 40 useful native species, including grasses for livestock, have been planted to cover 237 ha of farmer-managed land in 19 villages. The keen interest it has created has indicated that these figures will rise five-fold in the second year. These green bricks are the foundations of the living wall that will eventually reach across the Sahel and beyond. Keywords: restoration, seed germination, Sahel, plantation, native species, local communities, Great Green Wall

Exogenous nitric oxide improves salt tolerance during establishment of Jatropha curcas seedlings by ameliorating oxidative damage and toxic ion accumulation.

PubMed

Gadelha, Cibelle Gomes; Miranda, Rafael de Souza; Alencar, Nara Lídia M; Costa, José Hélio; Prisco, José Tarquinio; Gomes-Filho, Enéas

2017-05-01

Jatropha curcas is an oilseed species that is considered an excellent alternative energy source for fossil-based fuels for growing in arid and semiarid regions, where salinity is becoming a stringent problem to crop production. Our working hypothesis was that nitric oxide (NO) priming enhances salt tolerance of J. curcas during early seedling development. Under NaCl stress, seedlings arising from NO-treated seeds showed lower accumulation of Na + and Cl - than those salinized seedlings only, which was consistent with a better growth for all analyzed time points. Also, although salinity promoted a significant increase in hydrogen peroxide (H 2 O 2 ) content and membrane damage, the harmful effects were less aggressive in NO-primed seedlings. The lower oxidative damage in NO-primed stressed seedlings was attributed to operation of a powerful antioxidant system, including greater glutathione (GSH) and ascorbate (AsA) contents as well as catalase (CAT) and glutathione reductase (GR) enzyme activities in both endosperm and embryo axis. Priming with NO also was found to rapidly up-regulate the JcCAT1, JcCAT2, JcGR1 and JcGR2 gene expression in embryo axis, suggesting that NO-induced salt responses include functional and transcriptional regulations. Thus, NO almost completely abolished the deleterious salinity effects on reserve mobilization and seedling growth. In conclusion, NO priming improves salt tolerance of J. curcas during seedling establishment by inducing an effective antioxidant system and limiting toxic ion and reactive oxygen species (ROS) accumulation. Copyright © 2017 Elsevier GmbH. All rights reserved.

Microsite and elevation zone effects on seed pilferage, germination, and seedling survival during early whitebark pine recruitment.

PubMed

Pansing, Elizabeth R; Tomback, Diana F; Wunder, Michael B; French, Joshua P; Wagner, Aaron C

2017-11-01

Tree recruitment is a spatially structured process that may undergo change over time because of variation in postdispersal processes. We examined seed pilferage, seed germination, and seedling survival in whitebark pine to determine whether 1) microsite type alters the initial spatial pattern of seed caches, 2) higher abiotic stress (i.e. higher elevations) exacerbates spatial distribution changes, and 3) these postdispersal processes are spatially clustered. At two study areas, we created a seed distribution pattern by burying seed caches in microsite types frequently used by whitebark pine's avian seed disperser (Clark's nutcracker) in upper subalpine forest and at treeline, the latter characterized by high abiotic environmental stress. We monitored caches for two years for pilferage, germination, and seedling survival. Odds of pilferage (both study areas), germination (northern study area), and survival (southern study area) were higher at treeline relative to subalpine forest. At the southern study area, we found higher odds of 1) pilferage near rocks and trees relative to no object in subalpine forest, 2) germination near rocks relative to trees within both elevation zones, and 3) seedling survival near rocks and trees relative to no object at treeline. No microsite effects were detected at the northern study area. Findings indicated that the microsite distribution of seed caches changes with seed/seedling stage. Higher odds of seedling survival near rocks and trees were observed at treeline, suggesting abiotic stress may limit safe site availability, thereby shifting the spatial distribution toward protective microsites. Higher odds of pilferage at treeline, however, suggest rodents may limit treeline recruitment. Further, odds of pilferage were higher near rocks and trees relative to no object in subalpine forest but did not differ among microsites at treeline, suggesting pilferage can modulate the spatial structure of regeneration, a finding supported by limited clustering of postdispersal processes.

Morphological indicators of stock quality and field performance of red oak (Quercus rubra L.) seedling underplanted in a central Ontario shelterwood

Treesearch

Daniel C. Dey; William C. Parker

1997-01-01

Initial stem diameter of bareroot red oak planting stock was a better morphological indicator of future height and diameter growth in a shelterwood underplanting than were initial shoot length and number of first-order lateral roots. Stem diameter near the root collar provides an integrated measure of the growth potential of red oak planting stock because of its strong...

Exploration of plant growth and development using the European Modular Cultivation System facility on the International Space Station.

PubMed

Kittang, A-I; Iversen, T-H; Fossum, K R; Mazars, C; Carnero-Diaz, E; Boucheron-Dubuisson, E; Le Disquet, I; Legué, V; Herranz, R; Pereda-Loth, V; Medina, F J

2014-05-01

Space experiments provide a unique opportunity to advance our knowledge of how plants respond to the space environment, and specifically to the absence of gravity. The European Modular Cultivation System (EMCS) has been designed as a dedicated facility to improve and standardise plant growth in the International Space Station (ISS). The EMCS is equipped with two centrifuges to perform experiments in microgravity and with variable gravity levels up to 2.0 g. Seven experiments have been performed since the EMCS was operational on the ISS. The objectives of these experiments aimed to elucidate phototropic responses (experiments TROPI-1 and -2), root gravitropic sensing (GRAVI-1), circumnutation (MULTIGEN-1), cell wall dynamics and gravity resistance (Cell wall/Resist wall), proteomic identification of signalling players (GENARA-A) and mechanism of InsP3 signalling (Plant signalling). The role of light in cell proliferation and plant development in the absence of gravity is being analysed in an on-going experiment (Seedling growth). Based on the lessons learned from the acquired experience, three preselected ISS experiments have been merged and implemented as a single project (Plant development) to study early phases of seedling development. A Topical Team initiated by European Space Agency (ESA), involving experienced scientists on Arabidopsis space research experiments, aims at establishing a coordinated, long-term scientific strategy to understand the role of gravity in Arabidopsis growth and development using already existing or planned new hardware. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

Nitric oxide mediates strigolactone signaling in auxin and ethylene-sensitive lateral root formation in sunflower seedlings

PubMed Central

Bharti, Niharika; Bhatla, Satish C

2015-01-01

Strigolactones (SLs) play significant role in shaping root architecture whereby auxin-SL crosstalk has been observed in SL-mediated responses of primary root elongation, lateral root formation and adventitious root (AR) initiation. Whereas GR24 (a synthetic strigolactone) inhibits LR and AR formation, the effect of SL biosynthesis inhibitor (fluridone) is just the opposite (root proliferation). Naphthylphthalamic acid (NPA) leads to LR proliferation but completely inhibits AR development. The diffusive distribution of PIN1 in the provascular cells in the differentiating zone of the roots in response to GR24, fluridone or NPA treatments further indicates the involvement of localized auxin accumulation in LR development responses. Inhibition of LR formation by GR24 treatment coincides with inhibition of ACC synthase activity. Profuse LR development by fluridone and NPA treatments correlates with enhanced [Ca2+]cyt in the apical region and differentiating zones of LR, indicating a critical role of [Ca2+] in LR development in response to the coordinated action of auxins, ethylene and SLs. Significant enhancement of carotenoid cleavage dioxygenase (CCD) activity (enzyme responsible for SL biosynthesis) in tissue homogenates in presence of cPTIO (NO scavenger) indicates the role of endogenous NO as a negative modulator of CCD activity. Differences in the spatial distribution of NO in the primary and lateral roots further highlight the involvement of NO in SL-modulated root morphogenesis in sunflower seedlings. Present work provides new report on the negative modulation of SL biosynthesis through modulation of CCD activity by endogenous nitric oxide during SL-modulated LR development. PMID:26076049

Nitric oxide mediates strigolactone signaling in auxin and ethylene-sensitive lateral root formation in sunflower seedlings.

PubMed

Bharti, Niharika; Bhatla, Satish C

2015-01-01

Strigolactones (SLs) play significant role in shaping root architecture whereby auxin-SL crosstalk has been observed in SL-mediated responses of primary root elongation, lateral root formation and adventitious root (AR) initiation. Whereas GR24 (a synthetic strigolactone) inhibits LR and AR formation, the effect of SL biosynthesis inhibitor (fluridone) is just the opposite (root proliferation). Naphthylphthalamic acid (NPA) leads to LR proliferation but completely inhibits AR development. The diffusive distribution of PIN1 in the provascular cells in the differentiating zone of the roots in response to GR24, fluridone or NPA treatments further indicates the involvement of localized auxin accumulation in LR development responses. Inhibition of LR formation by GR24 treatment coincides with inhibition of ACC synthase activity. Profuse LR development by fluridone and NPA treatments correlates with enhanced [Ca(2+)]cyt in the apical region and differentiating zones of LR, indicating a critical role of [Ca(2+)] in LR development in response to the coordinated action of auxins, ethylene and SLs. Significant enhancement of carotenoid cleavage dioxygenase (CCD) activity (enzyme responsible for SL biosynthesis) in tissue homogenates in presence of cPTIO (NO scavenger) indicates the role of endogenous NO as a negative modulator of CCD activity. Differences in the spatial distribution of NO in the primary and lateral roots further highlight the involvement of NO in SL-modulated root morphogenesis in sunflower seedlings. Present work provides new report on the negative modulation of SL biosynthesis through modulation of CCD activity by endogenous nitric oxide during SL-modulated LR development.

Relation of quantity of seed sown and density of seedlings to the development and survival of forest planting stock

Treesearch

W. G. Wahlenberg

1929-01-01

It is obvious that seedlings grown in dense stands can not develop so well as those grown without crowding. Nurserymen naturally wish to avoid injury to their stock from crowding, but they also desire to utilize their soil space as fully as possible. The optimum density of stand for each species and age class of nursery stock can be determined within reasonably close...

Effects of shading on growth and development of northern red oak, black oak, black cherry, and red maple seedlings. I. height, diameter, and root/shoot ratio

Treesearch

Kurt W. Gottschalk

1985-01-01

Optimum light levels for shelterwood cutting to develop the large advance regeneration that require were investigated using eight shade-cloth treatments. Seedlings of northern red oak, black oak, black cherry and red maple were grow under these light treatments for 2 years. Height and diameter were measured annually, and samples were harvested for dry weight and leaf...

Adaptive transgenerational plasticity in an annual plant: grandparental and parental drought stress enhance performance of seedlings in dry soil.

PubMed

Herman, Jacob J; Sultan, Sonia E; Horgan-Kobelski, Tim; Riggs, Charlotte

2012-07-01

Stressful parental (usually maternal) environments can dramatically influence expression of traits in offspring, in some cases resulting in phenotypes that are adaptive to the inducing stress. The ecological and evolutionary impact of such transgenerational plasticity depends on both its persistence across generations and its adaptive value. Few studies have examined both aspects of transgenerational plasticity within a given system. Here we report the results of a growth-chamber study of adaptive transgenerational plasticity across two generations, using the widespread annual plant Polygonum persicaria as a naturally evolved model system. We grew five inbred Polygonum genetic lines in controlled dry vs. moist soil environments for two generations in a fully factorial design, producing replicate individuals of each genetic line with all permutations of grandparental and parental environment. We then measured the effects of these two-generational stress histories on traits critical for functioning in dry soil, in a third (grandchild) generation of seedling offspring raised in the dry treatment. Both grandparental and parental moisture environment significantly influenced seedling development: seedlings of drought-stressed grandparents or parents produced longer root systems that extended deeper and faster into dry soil compared with seedlings of the same genetic lines whose grandparents and/or parents had been amply watered. Offspring of stressed individuals also grew to a greater biomass than offspring of nonstressed parents and grandparents. Importantly, the effects of drought were cumulative over the course of two generations: when both grandparents and parents were drought-stressed, offspring had the greatest provisioning, germinated earliest, and developed into the largest seedlings with the most extensive root systems. Along with these functionally appropriate developmental effects, seedlings produced after two previous drought-stressed generations had significantly greater survivorship in very dry soil than did seedlings with no history of drought. These findings show that plastic responses to naturalistic resource stresses experienced by grandparents and parents can "preadapt" offspring for functioning under the same stresses in ways that measurably influence realized fitness. Possible implications of these environmentally-induced, inherited adaptations are discussed with respect to ecological distribution, persistence under novel stresses, and evolution in natural populations.

Controls of growth phenology vary in seedlings of three, co-occurring ecologically distinct northern conifers.

PubMed

Green, D Scott

2007-08-01

The objective of this study was to investigate the effects of temperature and seed-source elevation on height-growth phenology of three co-occurring and ecologically distinct northern conifers (Pinus contorta Dougl. ex Loud. var. latifolia (lodgepole pine), Picea glauca (Moench) Voss x Picea engelmannii Parry ex Engelm. (interior spruce) and Abies lasiocarpa (Hook.) Nutt. (subalpine fir)). Seed from populations of the three indigenous and co-occurring species was collected across an elevational transect on the southwestern slope of McBride Peak, near Prince George, BC. Collection sites were at elevations of 750 to 1850 m, the latter being close to the tree line. In 2003, seeds were germinated and seedlings raised under favorable growing conditions in a temperature-controlled glasshouse. In 2004, seedlings of each population were grown in natural daylengths at a location within 50 km of the seed collection site both in a temperature-controlled glasshouse and at a nearby field site, and height growth was recorded twice a week throughout the growing season. Species differed in both the date and the accumulated heat sum above 5 degrees C for the initiation and cessation of shoot extension. Growth durations (which integrate growth initiation and growth cessation) were more similar among species in the field than in the glasshouse. This suggests that different mechanisms of phenological control among co-occurring species can result in adaptive "equivalence" under a particular set of climatic conditions.

The Microphenotron: a robotic miniaturized plant phenotyping platform with diverse applications in chemical biology.

PubMed

Burrell, Thomas; Fozard, Susan; Holroyd, Geoff H; French, Andrew P; Pound, Michael P; Bigley, Christopher J; James Taylor, C; Forde, Brian G

2017-01-01

Chemical genetics provides a powerful alternative to conventional genetics for understanding gene function. However, its application to plants has been limited by the lack of a technology that allows detailed phenotyping of whole-seedling development in the context of a high-throughput chemical screen. We have therefore sought to develop an automated micro-phenotyping platform that would allow both root and shoot development to be monitored under conditions where the phenotypic effects of large numbers of small molecules can be assessed. The 'Microphenotron' platform uses 96-well microtitre plates to deliver chemical treatments to seedlings of Arabidopsis thaliana L. and is based around four components: (a) the 'Phytostrip', a novel seedling growth device that enables chemical treatments to be combined with the automated capture of images of developing roots and shoots; (b) an illuminated robotic platform that uses a commercially available robotic manipulator to capture images of developing shoots and roots; (c) software to control the sequence of robotic movements and integrate these with the image capture process; (d) purpose-made image analysis software for automated extraction of quantitative phenotypic data. Imaging of each plate (representing 80 separate assays) takes 4 min and can easily be performed daily for time-course studies. As currently configured, the Microphenotron has a capacity of 54 microtitre plates in a growth room footprint of 2.1 m 2 , giving a potential throughput of up to 4320 chemical treatments in a typical 10 days experiment. The Microphenotron has been validated by using it to screen a collection of 800 natural compounds for qualitative effects on root development and to perform a quantitative analysis of the effects of a range of concentrations of nitrate and ammonium on seedling development. The Microphenotron is an automated screening platform that for the first time is able to combine large numbers of individual chemical treatments with a detailed analysis of whole-seedling development, and particularly root system development. The Microphenotron should provide a powerful new tool for chemical genetics and for wider chemical biology applications, including the development of natural and synthetic chemical products for improved agricultural sustainability.

Endophytic bacteria in cacti seeds can improve the development of cactus seedlings.

Treesearch

M. Esther Puente; Ching Y. Li; Yoav Bashan

2009-01-01

A plant-bacterium association between the giant cardon cactus Pachycereus pringlei and endophytic bacteria help seedlings establish and grow on barren rock, This cactus, together with other desert plants, is responsible for weathering ancient lava flows in the Baja California Peninsula of Mexico.When cardon seeds are inoculated with endophytic...

Fall fertilization of Pinus resinosa seedlings: nutrient uptake, cold hardiness, and morphological development

Treesearch

M. Anisul Islam; Kent G. Apostol; Douglass F. Jacobs; R. Kasten Dumroese

2009-01-01

Fertilization is an integral component of nursery culture for production of high quality seedlings for afforestation and reforestation because it can enhance plant growth, nutrient storage reserves, and resistance to biotic and abiotic stresses (Landis, 1985). While fertilizer is conventionally applied during spring and summer in accordance with the...

Treating seedling and sapling stands for wildlife

Treesearch

Edwin D. Michael

1989-01-01

What you want to focus on during the seedling-sapling stage is understory development and species selection. By thinning newly regenerated stands you increase sunlight and therefore the abundance and nutritional value of herbaceous vegetation. Thinning allows you to favor understory species that provide browse, forage, and seeds for wildlife. Precommercial thinning in...

Accelerated development in johnsongrass seedlings (Sorghum halepense) suppresses the growth of native grasses through size-asymmetric competition

USDA-ARS?s Scientific Manuscript database

Superior competitive ability is an expected characteristic of grassland invaders, but not all invaders exhibit traits that convey a persistent growth advantage. Here we examine priority, expressed as a brief seedling growth burst, as the driving mechanism through which the exotic weed Johnsongrass ...

Natural seedlings and sprouts after regeneration cuttings in old-growth redwood

Treesearch

Kenneth N. Boe

1975-01-01

Natural regeneration of harvested old-growth stands of redwood (Sequoia sempervirens) is one way to start a new forest that is needed quickly for continuous timber production. Natural seedlings and sprouts developing after stands were cut were studied on the Redwood Experimental Forest, northern California. Three types of regeneration cuttings were...

Quantity-based versus quality-based pricing: Developing the niche pine seedling

Treesearch

Kirk D. Howell

2002-01-01

Demands placed on pine production in the southeastern part of the United States prompt managers to research and employ intensive cultural practices. Bareroot conifer seedling culture, like loblolly pine (Pinus taeda L.), is highly preferred in moderate regions of the South, since bareroot stock is relatively inexpensive to purchase, transporting and...

Evaluation of RPM™ oak seedlings in afforesting floodplain crop fields along the Missouri River

Treesearch

Daniel C. Dey; John M. Kabrick; Michael A. Gold

2005-01-01

Regenerating oaks in agricultural floodplains is problematic because of their slow juvenile shoot growth, intense plant competition, seasonal flooding, and browsing by wildlife. Planting large nursery stock has been recommended to increase the competitiveness of oak seedlings. The Forrest Keeling Nursery in Missouri developed the Root Production Method (RPM™)...

Environmentally induced development costs underlie fitness tradeoffs.

PubMed

Walter, Greg M; Wilkinson, Melanie J; Aguirre, J David; Blows, Mark W; Ortiz-Barrientos, Daniel

2018-06-01

Local adaptation can lead to genotype-by-environment interactions, which can create fitness tradeoffs in alternative environments, and govern the distribution of biodiversity across geographic landscapes. Exploring the ecological circumstances that promote the evolution of fitness tradeoffs requires identifying how natural selection operates and during which ontogenetic stages natural selection is strongest. When organisms disperse to areas outside their natural range, tradeoffs might emerge when organisms struggle to reach key life history stages, or alternatively, die shortly after reaching life history stages if there are greater risks of mortality associated with costs to developing in novel environments. We used multiple populations from four ecotypes of an Australian native wildflower (Senecio pinnatifolius) in reciprocal transplants to explore how fitness tradeoffs arise across ontogeny. We then assessed whether the survival probability for plants from native and foreign populations was contingent on reaching key developmental stages. We found that fitness tradeoffs emerged as ontogeny progressed when native plants were more successful than foreign plants at reaching seedling establishment and maturity. Native and foreign plants that failed to reach seedling establishment died at the same rate, but plants from foreign populations died quicker than native plants after reaching seedling establishment, and died quicker regardless of whether they reached sexual maturity or not. Development rates were similar for native and foreign populations, but changed depending on the environment. Together, our results suggest that natural selection for environment-specific traits early in life history created tradeoffs between contrasting environments. Plants from foreign populations were either unable to develop to seedling establishment, or they suffered increased mortality as a consequence of reaching seedling establishment. The observation of tradeoffs together with environmentally dependent changes in development rate suggest that foreign environments induce organisms to develop at a rate different from their native habitat, incurring consequences for lifetime fitness and population divergence. © 2018 by the Ecological Society of America.

Photocontrol of Anthocyanin Synthesis

PubMed Central

Mancinelli, A. L.; Yang, Chia-Ping Huang; Lindquist, P.; Anderson, O. R.; Rabino, I.

1975-01-01

Streptomycin enhances the synthesis of anthocyanins and inhibits the synthesis of chlorophylls and the development of chloroplasts in dark-grown seedlings of cabbage (Brassica oleracea), mustard (Sinapis alba), tomato (Lycopersicon esculentum), and turnip (Brassica rapa) exposed to prolonged periods of irradiation in various spectral regions. These results suggest that the contribution of photosynthesis to light-dependent high irradiance reaction anthocyanin synthesis in seedlings of cabbage, mustard, tomato, and turnip is minimal, if any at all. So far, phytochrome is the only photoreceptor whose action in the control of light-dependent anthocyanin synthesis in seedlings of cabbage, mustard, tomato, and turnip has been satisfactorily demonstrated. Images PMID:16659061

Photosynthetic Physiological Response of Radix Isatidis (Isatis indigotica Fort.) Seedlings to Nicosulfuron

PubMed Central

Ning, Na; Wen, Yinyuan; Dong, Shuqi; Yin, Meiqiang; Guo, Meijun; Wang, Binqiang; Feng, Lei; Guo, Pingyi

2014-01-01

Radix Isatidis (Isatis indigotica Fort.) is one of the most important traditional Chinese medicine plants. However, there is no suitable herbicide used for weed control in Radix Isatidis field during postemergence stage. To explore the safety of sulfonylurea herbicide nicosulfuron on Radix Isatidis (Isatis indigotica Fort.) seedlings and the photosynthetic physiological response of the plant to the herbicide, biological mass, leaf area, photosynthetic pigment content, photosynthetic rate, chlorophyll fluorescence characteristics, and P700 parameters of Radix Isatidis seedlings were analyzed 10 d after nicosulfuron treatment at 5th leaf stage in this greenhouse research. The results showed that biological mass, total chlorophyll, chlorophyll a, and carotenoids content, photosynthetic rate, stomatal conductance, PS II maximum quantum yield, PS II effective quantum yield, PS II electron transport rate, photochemical quenching, maximal P700 change, photochemical quantum yield of PS I, and PS I electron transport rate decreased with increasing herbicide concentrations, whereas initial fluorescence, quantum yield of non-regulated energy dissipation in PS II and quantum yield of non-photochemical energy dissipation due to acceptor side limitation in PS I increased. It suggests that nicosulfuron ≥1 mg L−1 causes the damage of chloroplast, PS II and PS I structure. Electron transport limitations in PS I receptor side, and blocked dark reaction process may be the main cause of the significantly inhibited growth and decreased photosynthetic rate of Radix Isatidis seedlings. PMID:25165819

The Choline/Ethanolamine Kinase Family in Arabidopsis: Essential Role of CEK4 in Phospholipid Biosynthesis and Embryo Development

PubMed Central

2015-01-01

Phospholipids are highly conserved and essential components of biological membranes. The major phospholipids, phosphatidylethanolamine and phosphatidylcholine (PtdCho), are synthesized by the transfer of the phosphoethanolamine or phosphocholine polar head group, respectively, to the diacylglycerol backbone. The metabolism of the polar head group characterizing each phospholipid class is poorly understood; thus, the biosynthetic pathway of major phospholipids remains elusive in Arabidopsis thaliana. The choline/ethanolamine kinase (CEK) family catalyzes the initial steps of phospholipid biosynthesis. Here, we analyzed the function of the four CEK family members present in Arabidopsis. Knocking out of CEK4 resulted in defective embryo development, which was complemented by transformation of genomic CEK4. Reciprocal genetic crossing suggested that CEK4 knockout causes embryonic lethality, and microscopy analysis of the aborted embryos revealed developmental arrest after the heart stage, with no defect being found in the pollen. CEK4 is preferentially expressed in the vasculature, organ boundaries, and mature embryos, and CEK4 was mainly localized to the plasma membrane. Overexpression of CEK4 in wild-type Arabidopsis increased the levels of PtdCho in seedlings and mature siliques and of major membrane lipids in seedlings and triacylglycerol in mature siliques. CEK4 may be the plasma membrane-localized isoform of the CEK family involved in the rate-limiting step of PtdCho biosynthesis and appears to be required for embryo development in Arabidopsis. PMID:25966764

Gravitropism and development of wild-type and starch-deficient mutants of Arabidopsis during spaceflight

NASA Technical Reports Server (NTRS)

Kiss, J. Z.; Katembe, W. J.; Edelmann, R. E.

1998-01-01

The "starch-statolith" hypothesis has been used by plant physiologists to explain the gravity perception mechanism in higher plants. In order to help resolve some of the controversy associated with ground-based research that has supported this theory, we performed a spaceflight experiment during the January 1997 mission of the Space Shuttle STS-81. Seedlings of wild-type (WT) Arabidopsis, two reduced-starch strains, and a starchless mutant were grown in microgravity and then given a gravity stimulus on a centrifuge. In terms of development in space, germination was greater than 90% for seeds in microgravity, and flight seedlings were smaller (60% in total length) compared to control plants grown on the ground and to control plants on a rotating clinostat. Seedlings grown in space had two structural features that distinguished them from the controls: a greater density of root hairs and an anomalous hypocotyl hook structure. However, the slower growth and morphological changes observed in the flight seedlings may be due to the effects of ethylene present in the spacecraft. Nevertheless, during the flight hypocotyls of WT seedlings responded to a unilateral 60 min stimulus provided by a 1-g centrifuge while those of the starch-deficient strains did not. Thus the strain with the greatest amount of starch responded to the stimulus given in flight and therefore, these data support the starch-statolith model for gravity sensing.

Early root growth and architecture of fast- and slow-growing Norway spruce (Picea abies) families differ-potential for functional adaptation.

PubMed

Hamberg, Leena; Velmala, Sannakajsa M; Sievänen, Risto; Kalliokoski, Tuomo; Pennanen, Taina

2018-06-01

The relationship between the growth rate of aboveground parts of trees and fine root development is largely unknown. We investigated the early root development of fast- and slow-growing Norway spruce (Picea abies (L.) H. Karst.) families at a developmental stage when the difference in size is not yet observed. Seedling root architecture data, describing root branching, were collected with the WinRHIZO™ image analysis system, and mixed models were used to determine possible differences between the two growth phenotypes. A new approach was used to investigate the spatial extent of root properties along the whole sample root from the base of 1-year-old seedlings to the most distal part of a root. The root architecture of seedlings representing fast-growing phenotypes showed ~30% higher numbers of root branches and tips, which resulted in larger root extensions and potentially a better ability to acquire nutrients. Seedlings of fast-growing phenotypes oriented and allocated root tips and biomass further away from the base of the seedling than those growing slowly, a possible advantage in nutrient-limited and heterogeneous boreal forest soils. We conclude that a higher long-term growth rate of the aboveground parts in Norway spruce may relate to greater allocation of resources to explorative roots that confers a competitive edge during early growth phases in forest ecosystems.

Genome Wide Association Study of Seedling and Adult Plant Leaf Rust Resistance in Elite Spring Wheat Breeding Lines.

PubMed

Gao, Liangliang; Turner, M Kathryn; Chao, Shiaoman; Kolmer, James; Anderson, James A

2016-01-01

Leaf rust is an important disease, threatening wheat production annually. Identification of resistance genes or QTLs for effective field resistance could greatly enhance our ability to breed durably resistant varieties. We applied a genome wide association study (GWAS) approach to identify resistance genes or QTLs in 338 spring wheat breeding lines from public and private sectors that were predominately developed in the Americas. A total of 46 QTLs were identified for field and seedling traits and approximately 20-30 confer field resistance in varying degrees. The 10 QTLs accounting for the most variation in field resistance explained 26-30% of the total variation (depending on traits: percent severity, coefficient of infection or response type). Similarly, the 10 QTLs accounting for most of the variation in seedling resistance to different races explained 24-34% of the variation, after correcting for population structure. Two potentially novel QTLs (QLr.umn-1AL, QLr.umn-4AS) were identified. Identification of novel genes or QTLs and validation of previously identified genes or QTLs for seedling and especially adult plant resistance will enhance understanding of leaf rust resistance and assist breeding for resistant wheat varieties. We also developed computer programs to automate field and seedling rust phenotype data conversions. This is the first GWAS study of leaf rust resistance in elite wheat breeding lines genotyped with high density 90K SNP arrays.

In vitro propagation of northern red oak (Quercus rubra L.)

Treesearch

G. Vengadesan; Paula M. Pijut

2009-01-01

In vitro propagation of northern red oak (Quercus rubra) shoots was successful from cotyledonary node explants excised from 8-wk-old in vitro grown seedlings. Initially, four shoots per explant were obtained on Murashige and Skoog (MS) medium supplemented with 4.4 µM 6-benzylaminopurine (BA), 0.45 ...

Recognizing all-aged hemlock forests

Treesearch

Orie L. Loucks; James Nighswander

2000-01-01

Eastern hemlock (Tsuga canadensis (L.) Carr.) occurs in old-growth stands sometimes over 400 years old, throughout its principal range from Nova Scotia to Wisconsin. Studies based on aging as well as diameter distributions indicate a stand structure often dominated by an initial multi-decade post-disturbance pulse of seedling establishment, followed...

Predicting the effects of hardwood competition on red pine seedling growth

Treesearch

Alan S. White; Katherine J. Elliott

1992-01-01

Pin cherry (Prunus pensylvanica L.f.) and striped maple (Acer pensylvanicum L.) are potentially important competitors of red pine (Pinus resinosa Ait) planted on recently clear-cut hardwood sites. By experimentally manipulating initial competitor densities on 2.0-m2 plots, we were able to...

Identification of Vigor Related Transcripts in Beta vulgaris When Germinated Under Abiotic Stress

USDA-ARS?s Scientific Manuscript database

Germination is the first opportunity to evaluate vigor for beet breeders. The initial condition a germinating seed encounters affects the speed and success of germination, the amount of stored energy reserves to withstand future stress, and the overall ability of the seedling to flourish. However, s...

Blue and Valley Oak Seedling Establishment on California's Hardwood Rangelands

Treesearch

Theodore E. Adams Jr.; Peter B. Sands; William H. Weitkamp; Neil K. McDougald

1991-01-01

Factors contributing to poor establishment of blue oak (Quercus douglasii) and valley oak (Q. lobata) in California oak-grassland savannas were studied in a series of acorn seeding experiments initiated in 1985. Exclusion of large herbivores permitted examination of herbaceous interference and small mammal and insect depredation....

Heterosis in rice seedlings: its relationship to gibberellin content and expression of gibberellin metabolism and signaling genes.

PubMed

Ma, Qian; Hedden, Peter; Zhang, Qifa

2011-08-01

Despite the accumulation of data on the genetic and molecular understanding of heterosis, there is little information on the regulation of heterosis at the physiological level. In this study, we performed a quantitative analysis of endogenous gibberellin (GA) content and expression profiling of the GA metabolism and signaling genes to investigate the possible relationship between GA signaling and heterosis for seedling development in rice (Oryza sativa). The materials used were an incomplete diallele set of 3 × 3 crosses and the six parents. In the growing shoots of the seedlings at 20 d after sowing, significant positive correlations between the contents of some GA species and performance and heterosis based on shoot dry mass were detected. Expression analyses of GA-related genes by real-time reverse transcription-polymerase chain reaction revealed that 13 out of the 16 GA-related genes examined exhibited significant differential expression among the F1 hybrid and its parents, acting predominantly in the modes of overdominance and positive dominance. Expression levels of nine genes in the hybrids displayed significant positive correlations with the heterosis of shoot dry mass. These results imply that GAs play a positive role in the regulation of heterosis for rice seedling development. In shoots plus root axes of 4-d-old germinating seeds that had undergone the deetiolation, mimicking normal germination in soil, the axis dry mass was positively correlated with the content of GA₂₉ but negatively correlated with that of GA₁₉. Our findings provide supporting evidence for GAs playing an important regulatory role in heterosis for rice seedling development.

Effect of heavy metals on seed germination and seedling growth of common ragweed and roadside ground cover legumes.

PubMed

Bae, Jichul; Benoit, Diane L; Watson, Alan K

2016-06-01

In southern Québec, supplement roadside ground covers (i.e. Trifolium spp.) struggle to establish near edges of major roads and thus fail to assist turf recruitment. It creates empty niches vulnerable to weed establishment such as common ragweed (Ambrosia artemisiifolia). We hypothesized that heavy metal stresses may drive such species shifts along roadside edges. A growth chamber experiment was conducted to assess effects of metals (Zn, Pb, Ni, Cu, and Cd) on germination and seedling behaviors of roadside weed (A. artemisiifolia) and ground cover legumes (Coronilla varia, Lotus corniculatus, and Trifolium arvense). All metals inhibited T. arvense germination, but the effect was least on A. artemisiifolia. Low levels of Pb and Ni promoted germination initiation of A. artemisiifolia. Germination of L. corniculatus was not affected by Zn, Pb, and Ni, but inhibited by Cu and Cd. Germination of C. varia was decreased by Ni, Cu, and Cd and delayed by Zn and Pb. Metal additions hindered seedling growth of all test species, and the inhibitory effect on the belowground growth was greater than on the aboveground growth. Seedling mortality was lowest in A. artemisiifolia but highest in T. arvense when exposed to the metal treatments. L. corniculatus and C. varia seedlings survived when subjected to high levels of Zn, Pb, and Cd. In conclusion, the successful establishment of A. artemisiifolia along roadside edges can be associated with its greater tolerance of heavy metals. The findings also revealed that L. corniculatus is a potential candidate for supplement ground cover in metal-contaminated roadside edges in southern Québec, especially sites contaminated with Zn and Pb. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of soil type and light on height growth, biomass partitioning, and nitrogen dynamics on 22 species of tropical dry forest tree seedlings: Comparisons between legumes and nonlegumes.

PubMed

Smith-Martin, Christina M; Gei, Maria G; Bergstrom, Ellie; Becklund, Kristen K; Becknell, Justin M; Waring, Bonnie G; Werden, Leland K; Powers, Jennifer S

2017-03-01

The seedling stage is particularly vulnerable to resource limitation, with potential consequences for community composition. We investigated how light and soil variation affected early growth, biomass partitioning, morphology, and physiology of 22 tree species common in tropical dry forest, including eight legumes. Our hypothesis was that legume seedlings are better at taking advantage of increased resource availability, which contributes to their successful regeneration in tropical dry forests. We grew seedlings in a full-factorial design under two light levels in two soil types that differed in nutrient concentrations and soil moisture. We measured height biweekly and, at final harvest, biomass partitioning, internode segments, leaf carbon, nitrogen, δ 13 C, and δ 15 N. Legumes initially grew taller and maintained that height advantage over time under all experimental conditions. Legumes also had the highest final total biomass and water-use efficiency in the high-light and high-resource soil. For nitrogen-fixing legumes, the amount of nitrogen derived from fixation was highest in the richer soil. Although seed mass tended to be larger in legumes, seed size alone did not account for all the differences between legumes and nonlegumes. Both belowground and aboveground resources were limiting to early seedling growth and function. Legumes may have a different regeneration niche, in that they germinate rapidly and grow taller than other species immediately after germination, maximizing their performance when light and belowground resources are readily available, and potentially permitting them to take advantage of high light, nutrient, and water availability at the beginning of the wet season. © 2017 Botanical Society of America.

Effects of stress temperatures of germination on polyamine titers of soybean seeds

NASA Astrophysics Data System (ADS)

Pineda-Mejia, Renan

High and low stress temperatures during seed germination and seedling development limit total germination and the rate of germination and growth. Changes in polyamine (PA) concentrations in seeds of different species have been associated with germination, growth and environmental stresses such as temperature, drought, oxygen, chilling injury and osmotic conditions. Two studies were conducted to determine the effect of stress temperatures during germination and seedling development on polyamine titers in soybean seeds. Three germination temperatures, 25, 30, and 36°C were used in the first study to evaluate their influence on changes in polyamine concentrations in soybean seeds germinated at 76 and 90 hours. The polyamines (PAs), cadaverine (Cad), putrescine (Put), spermidine (Spd), agmatine (Agm), and spermine (Spin) were quantified by HPLC using a cation exchange column and an electrochemical detector. Cad, Put, Agm, and Spd declined as the germination temperatures increased from 25 to 36°C. Conversely, Spin increased considerably with an increase in temperature. Total germination was reduced from 97.2 to 92.5% as germination temperatures increased from 25 to 36°C. Germination time did not affect Cad, Agm and Spm, and total germination, however, the interaction between temperature and germination time for Put and Spd concentrations was significant. In the second study, changes in PA concentrations, seedling growth, germination time (t50), fresh and dry weight, and moisture content were measured in the embryonic axis and cotyledons of soybean seeds germinated at 10 and 25°C through six stages of germination dry seed (DS), testa split (TS), radicle at 10 mm (Ra-10), root hairs visible (RHV), secondary root primordia (SRP), and complete seedling (CS). The concentrations of Cad and Put in the embryonic axis, were significantly higher in seeds germinated under low temperature than in seeds at 25°C (approximately 10 and 3 fold respectively). However, this difference was not observed until the last three stages of germination. The stage of germination also influenced the levels of these polyamines. The concentrations of Cad and Put detected at the CS stage were 50 and 18 fold respectively, relative to the initial concentrations found at the DS stage. Spd levels in seeds under stress temperatures also increased, but to a lesser extent compared to Cad and Put. Differences in Spd concentrations between temperatures were observed only at the CS stage. Agm concentrations were higher at 25 than at 10°C at SRP and CS. Spm concentrations of seeds germinated at 25°C remained higher during the first four stages of development but at the end of germination, seeds at 10°C had higher quantities of Spm. In the cotyledons, Polyamines tended to decline with stages of germination, regardless of the temperature. However, Agm levels increased in the cotyledons of soybean seeds. Maximum dry weight and seedling growth was found at RHV, SRP, and CS. Maximum levels of Cad and Put were also found during these stages. Spd increased with both temperatures from DS to Ra-10, thereafter, Spd levels in seeds at 10°C continued increasing while seeds at 25°C declined. High and low stress germination temperatures caused significant changes in polyamine concentrations, reduced germination and seedling growth of soybean seeds.

Transcriptomic Profiling of the Maize (Zea mays L.) Leaf Response to Abiotic Stresses at the Seedling Stage.

PubMed

Li, Pengcheng; Cao, Wei; Fang, Huimin; Xu, Shuhui; Yin, Shuangyi; Zhang, Yingying; Lin, Dezhou; Wang, Jianan; Chen, Yufei; Xu, Chenwu; Yang, Zefeng

2017-01-01

Abiotic stresses, including drought, salinity, heat, and cold, negatively affect maize ( Zea mays L.) development and productivity. To elucidate the molecular mechanisms of resistance to abiotic stresses in maize, RNA-seq was used for global transcriptome profiling of B73 seedling leaves exposed to drought, salinity, heat, and cold stress. A total of 5,330 differentially expressed genes (DEGs) were detected in differential comparisons between the control and each stressed sample, with 1,661, 2,019, 2,346, and 1,841 DEGs being identified in comparisons of the control with salinity, drought, heat, and cold stress, respectively. Functional annotations of DEGs suggested that the stress response was mediated by pathways involving hormone metabolism and signaling, transcription factors (TFs), very-long-chain fatty acid biosynthesis and lipid signaling, among others. Of the obtained DEGs (5,330), 167 genes are common to these four abiotic stresses, including 10 up-regulated TFs (five ERFs, two NACs, one ARF, one MYB, and one HD-ZIP) and two down-regulated TFs (one b-ZIP and one MYB-related), which suggested that common mechanisms may be initiated in response to different abiotic stresses in maize. This study contributes to a better understanding of the molecular mechanisms of maize leaf responses to abiotic stresses and could be useful for developing maize cultivars resistant to abiotic stresses.

[Influence of cutting seedling on growth, quality and yield of both aerial and underground part by cutting seedling in Scutellaria baicalensis].

PubMed

Liu, Rong-Xiu; Li, Yong-Jie; Li, Lin; Miao, Xiao-Su; Wang, Xue-Sen; Zhang, Dan; Wei, Sheng-Li

2016-06-01

By measuring the growth data of Scutellaria baicalensis in different cutting-seedling and determined active ingredient contents by HPLC and ultraviolet spectrophotometric determination. such as flavonoids. baicalin. wogonoside. baicalein. wogonin. oroxylin A. scutellarin. luteolin. and apigenin in the whole plant. Under circumstances of guaranteeing the quality and yield of medicinal materials. the yield of medicinal materials. and stems and leaves reached 193.60,63.21 kg/mu after twice cutting seedling. Not only yield but also active ingredient contents have been improved to some extent. the contents of flavonoids. baicalin. wogonoside. baicalein. wogonin. oroxylin A reached 18.52%. 15.13%. 4.03%. 1.04%. 1.04%. 0.12%. respectively in roots. Luteolin was not detected in young stems and leaves of S. baicalensis,the contents of other active ingredients such as scutellarin. luteolin and apigenin reached 7.00%. 0.96%. 0.04% respectively under twice cutting seedling. Therefore. regular cutting seedling could be regard as a new cultivation technique for wider range of promotion. And gaining high quality and yield of medicinal materials and tea with the purpose of rational utilization of natural resources and promoting the development of integration of herbal combination. Copyright© by the Chinese Pharmaceutical Association.

Tree genetics defines fungal partner communities that may confer drought tolerance.

PubMed

Gehring, Catherine A; Sthultz, Christopher M; Flores-Rentería, Lluvia; Whipple, Amy V; Whitham, Thomas G

2017-10-17

Plant genetic variation and soil microorganisms are individually known to influence plant responses to climate change, but the interactive effects of these two factors are largely unknown. Using long-term observational studies in the field and common garden and greenhouse experiments of a foundation tree species ( Pinus edulis ) and its mutualistic ectomycorrhizal fungal (EMF) associates, we show that EMF community composition is under strong plant genetic control. Seedlings acquire the EMF community of their seed source trees (drought tolerant vs. drought intolerant), even when exposed to inoculum from the alternate tree type. Drought-tolerant trees had 25% higher growth and a third the mortality of drought-intolerant trees over the course of 10 y of drought in the wild, traits that were also observed in their seedlings in a common garden. Inoculation experiments show that EMF communities are critical to drought tolerance. Drought-tolerant and drought-intolerant seedlings grew similarly when provided sterile EMF inoculum, but drought-tolerant seedlings grew 25% larger than drought-intolerant seedlings under dry conditions when each seedling type developed its distinct EMF community. This demonstration that particular combinations of plant genotype and mutualistic EMF communities improve the survival and growth of trees with drought is especially important, given the vulnerability of forests around the world to the warming and drying conditions predicted for the future.

Root architecture simulation improves the inference from seedling root phenotyping towards mature root systems

PubMed Central

Zhao, Jiangsan; Rewald, Boris; Leitner, Daniel; Nagel, Kerstin A.; Nakhforoosh, Alireza

2017-01-01

Abstract Root phenotyping provides trait information for plant breeding. A shortcoming of high-throughput root phenotyping is the limitation to seedling plants and failure to make inferences on mature root systems. We suggest root system architecture (RSA) models to predict mature root traits and overcome the inference problem. Sixteen pea genotypes were phenotyped in (i) seedling (Petri dishes) and (ii) mature (sand-filled columns) root phenotyping platforms. The RSA model RootBox was parameterized with seedling traits to simulate the fully developed root systems. Measured and modelled root length, first-order lateral number, and root distribution were compared to determine key traits for model-based prediction. No direct relationship in root traits (tap, lateral length, interbranch distance) was evident between phenotyping systems. RootBox significantly improved the inference over phenotyping platforms. Seedling plant tap and lateral root elongation rates and interbranch distance were sufficient model parameters to predict genotype ranking in total root length with an RSpearman of 0.83. Parameterization including uneven lateral spacing via a scaling function substantially improved the prediction of architectures underlying the differently sized root systems. We conclude that RSA models can solve the inference problem of seedling root phenotyping. RSA models should be included in the phenotyping pipeline to provide reliable information on mature root systems to breeding research. PMID:28168270

N-Acylethanolamine metabolism interacts with abscisic acid signaling in Arabidopsis thaliana seedlings.

PubMed

Teaster, Neal D; Motes, Christy M; Tang, Yuhong; Wiant, William C; Cotter, Matthew Q; Wang, Yuh-Shuh; Kilaru, Aruna; Venables, Barney J; Hasenstein, Karl H; Gonzalez, Gabriel; Blancaflor, Elison B; Chapman, Kent D

2007-08-01

N-Acylethanolamines (NAEs) are bioactive acylamides that are present in a wide range of organisms. In plants, NAEs are generally elevated in desiccated seeds, suggesting that they may play a role in seed physiology. NAE and abscisic acid (ABA) levels were depleted during seed germination, and both metabolites inhibited the growth of Arabidopsis thaliana seedlings within a similar developmental window. Combined application of low levels of ABA and NAE produced a more dramatic reduction in germination and growth than either compound alone. Transcript profiling and gene expression studies in NAE-treated seedlings revealed elevated transcripts for a number of ABA-responsive genes and genes typically enriched in desiccated seeds. The levels of ABI3 transcripts were inversely associated with NAE-modulated growth. Overexpression of the Arabidopsis NAE degrading enzyme fatty acid amide hydrolase resulted in seedlings that were hypersensitive to ABA, whereas the ABA-insensitive mutants, abi1-1, abi2-1, and abi3-1, exhibited reduced sensitivity to NAE. Collectively, our data indicate that an intact ABA signaling pathway is required for NAE action and that NAE may intersect the ABA pathway downstream from ABA. We propose that NAE metabolism interacts with ABA in the negative regulation of seedling development and that normal seedling establishment depends on the reduction of the endogenous levels of both metabolites.

Arabidopsis WRKY6 Transcription Factor Acts as a Positive Regulator of Abscisic Acid Signaling during Seed Germination and Early Seedling Development

PubMed Central

Wu, Wei-Hua; Chen, Yi-Fang

2016-01-01

The phytohormone abscisic acid (ABA) plays important roles during seed germination and early seedling development. Here, we characterized the function of the Arabidopsis WRKY6 transcription factor in ABA signaling. The transcript of WRKY6 was repressed during seed germination and early seedling development, and induced by exogenous ABA. The wrky6-1 and wrky6-2 mutants were ABA insensitive, whereas WRKY6-overexpressing lines showed ABA-hypersensitive phenotypes during seed germination and early seedling development. The expression of RAV1 was suppressed in the WRKY6-overexpressing lines and elevated in the wrky6 mutants, and the expression of ABI3, ABI4, and ABI5, which was directly down-regulated by RAV1, was enhanced in the WRKY6-overexpressing lines and repressed in the wrky6 mutants. Electrophoretic mobility shift and chromatin immunoprecipitation assays showed that WRKY6 could bind to the RAV1 promoter in vitro and in vivo. Overexpression of RAV1 in WRKY6-overexpressing lines abolished their ABA-hypersensitive phenotypes, and the rav1 wrky6-2 double mutant showed an ABA-hypersensitive phenotype, similar to rav1 mutant. Together, the results demonstrated that the Arabidopsis WRKY6 transcription factor played important roles in ABA signaling by directly down-regulating RAV1 expression. PMID:26829043

Ultrastructure of meristem and root cap of pea seedlings under spaceflight conditions

NASA Technical Reports Server (NTRS)

Sytnyk, K. M.; Kordyum, E. L.; Bilyavska, N. O.; Tarasenko, V. O.

1983-01-01

Data of electron microscopic analysis of meristem and root cap of pea seedlings grown aboard the Salyut-6 orbital research station in the Oazis apparatus and in the laboratory are presented. The main morphological and anatomical characteristics of the test and control plants are shown to be similar. At the same time, some differences are found in the structural and functional organization of the experimental cells as compared to the controls. They concern first of all the plastic apparatus, mitochondria and Golgi apparatus. It is assumed that cell function for certain periods of weightlessness on the whole ensures execution of the cytodifferentiation programs genetically determined on the Earth. Biochemical and physiological processes vary rather markedly due to lack of initially rigorous determination.

Effects of flooding regime and seedling treatment on early survival and growth of nuttall oak

USGS Publications Warehouse

Burkett, V.R.; Draugelis-Dale, R.O.; Williams, H.M.; Schoenholtz, S.H.

2005-01-01

Effects of flooding on survival and growth of three different types of Nuttall oak (Quercus texana Buckl.) seedlings were observed at the end of third and fifth growing seasons at Yazoo National Wildlife Refuge, Mississippi, U.S.A. Three types of seedlings were planted in January 1995 in a split-plot design, with four replications at each of two elevations on floodprone, former cropland in Sharkey clay soil. The lower of the two planting elevations was inundated for 21 days during the first growing season, whereas the higher elevation did not flood during the 5-year period of this study. The three types of 1-0 seedlings were bareroot seedlings, seedlings grown in containers (3.8 ?? 21a??cm plastic seedling cones), and container-grown seedlings inoculated with vegetative mycelia of Pisolithus tinctorius (Pers.) Coker. Survival of all the three seedling types was greatest at the lower, intermittently flooded elevation, indicating that drought and related effects on plant competition were more limiting to seedling survival than flooding. At the lower elevation, survival of mycorrhizal-inoculated container seedlings was greater than that of noninoculated container seedlings. Survival among bareroot seedlings and inoculated container seedlings was not significantly different at either elevation. At the higher, nonflooded elevation, however, bareroot seedling survival was greater than the survival of container seedlings without inoculation. Differences were significant among the inoculated and the noninoculated container seedlings, with higher survival of inoculated seedlings at both elevations, though differences were only significant in year 3. At the end of the fifth year, height of bareroot seedlings was significantly greater than the heights of both types of container-grown seedlings at both planting elevations. Because seedlings grown in the plastic seedlings cones did not survive better than the bareroot seedlings at either planting elevation, the bareroot stock appear to be the economically superior choice for regeneration in Sharkey soil.

Effect of alternating day and night temperature on short day-induced bud set and subsequent bud burst in long days in Norway spruce

PubMed Central

Olsen, Jorunn E.; Lee, YeonKyeong; Junttila, Olavi

2014-01-01

Young seedlings of the conifer Norway spruce exhibit short day (SD)-induced cessation of apical growth and bud set. Although different, constant temperatures under SD are known to modulate timing of bud set and depth of dormancy with development of deeper dormancy under higher compared to lower temperature, systematic studies of effects of alternating day (DT) and night temperatures (NT) are limited. To shed light on this, seedlings of different provenances of Norway spruce were exposed to a wide range of DT-NT combinations during bud development, followed by transfer to forcing conditions of long days (LD) and 18°C, directly or after different periods of chilling. Although no specific effect of alternating DT/NT was found, the results demonstrate that the effects of DT under SD on bud set and subsequent bud break are significantly modified by NT in a complex way. The effects on bud break persisted after chilling. Since time to bud set correlated with the daily mean temperature under SD at DTs of 18 and 21°C, but not a DT of 15°C, time to bud set apparently also depend on the specific DT, implying that the effect of NT depends on the actual DT. Although higher temperature under SD generally results in later bud break after transfer to forcing conditions, the fastest bud flush was observed at intermediate NTs. This might be due to a bud break-hastening chilling effect of intermediate compared to higher temperatures, and delayed bud development to a stage where bud burst can occur, under lower temperatures. Also, time to bud burst in un-chilled seedlings decreased with increasing SD-duration, suggesting that bud development must reach a certain stage before the processes leading to bud burst are initiated. The present results also indicate that low temperature during bud development had a larger effect on the most southern compared to the most northern provenance studied. Decreasing time to bud burst was observed with increasing northern latitude of origin in un-chilled as well as chilled plants. In conclusion, being a highly temperature-dependent process, bud development is strongly delayed by low temperature, and the effects of DT is significantly modified by NT in a complex manner. PMID:25538722

The Parasitic Plant Cuscuta australis Is Highly Insensitive to Abscisic Acid-Induced Suppression of Hypocotyl Elongation and Seed Germination

PubMed Central

Li, Juan; Hettenhausen, Christian; Sun, Guiling; Zhuang, Huifu; Li, Jian-Hong; Wu, Jianqiang

2015-01-01

Around 1% of angiosperms are parasitic plants. Their growth and development solely or partly depend on host plants from which they extract water, nutrients, and other molecules using a parasitic plant-specific organ, the haustorium. Strong depletion of nutrients can result in serious growth retardation and in some cases, death of the hosts. The genus Cuscuta (dodder) comprises about 200 holoparasitic species occurring on all continents. Their seedlings have no roots and cotyledons but are only string-like hypocotyls. When they contact suitable host plants, haustoria are formed and thereafter seedlings rapidly develop into vigorously growing branches without roots and leaves. This highly specialized lifestyle suggests that Cuscuta plants likely have unique physiology in development and stress responses. Using germination and seedling growth assays, we show that C. australis seeds and seedlings are highly insensitive to abscisic acid (ABA). Transcriptome analysis and protein sequence alignment with Arabidopsis, tomato, and rice homologs revealed that C. australis most likely consists of only four functional ABA receptors. Given that Cuscuta plants are no longer severely challenged by drought stress, we hypothesize that the ABA-mediated drought resistance pathway in Cuscuta spp. might have had degenerated over time during evolution. PMID:26258814

The Novel Approach to Enhance Seed Security: Dual Anti-Counterfeiting Methods Applied on Tobacco Pelleted Seeds

PubMed Central

Guan, Yajing; Wang, Jianchen; Tian, Yixin; Hu, Weimin; Zhu, Liwei; Zhu, Shuijin; Hu, Jin

2013-01-01

Seed security is of prime importance for agriculture. To protect true seeds from being faked, more secure dual anti-counterfeiting technologies for tobacco (Nicotiana tabacum L.) pelleted seed were developed in this paper. Fluorescein (FR), rhodamine B (RB), and magnetic powder (MP) were used as anti-counterfeiting labels. According to their different properties and the special seed pelleting process, four dual-labeling treatments were conducted for two tobacco varieties, MS Yunyan85 (MSYY85) and Honghua Dajinyuan (HHDJY). Then the seed germination and seedling growth status were investigated, and the fluorescence in cracked pellets and developing seedlings was observed under different excitation lights. The results showed that FR, RB, and MP had no negative effects on the germination, seedling growth, and MDA content of the pelleted seeds, and even some treatments significantly enhanced seedling dry weight, vigor index, and shoot height in MS YY85, and increased SOD activity and chlorophyll content in HHDJY as compared to the control. In addition, the cotyledon tip of seedlings treated with FR and MP together represented bright green fluorescence under illumination of blue light (478 nm). And the seedling cotyledon vein treated with RB and MP together showed red fluorescence under green light (546 nm). All seeds pelleted with magnetic powder of proper concentration could be attracted by a magnet. Thus, it indicated that those new dual-labeling methods that fluorescent compound and magnetic powder simultaneously applied in the same seed pellets definitely improved anti-counterfeiting technology and enhanced the seed security. This technology will ensure that high quality seed will be used in the crop production. PMID:23468953

Mechanisms for the development of genetically variable mycorrhizal mycelia in the ectomycorrhizal fungus Laccaria bicolor.

PubMed Central

de la Bastide, P Y; Kropp, B R; Piché, Y

1995-01-01

An in vitro study investigated mechanisms for the development of genetically variable mycorrhizal mycelia for Laccaria bicolor. Seedlings of jack pine (Pinus banksiana) grown nonaseptically in an autoclaved soil substrate were given different L. bicolor inoculum treatments. These included (i) a dikaryotic mycelium genotype (D); (ii) D and basidiospores collected from one group of five sporophores (T1); (iii) D and basidiospores collected from 10 sporophores, two from each of five different groups (T5); (iv) T1 alone; (v) T5 alone; and (vi) a noninoculated control. Dikaryotic mycelial inoculum was provided at the time of sowing, while basidiospore inoculum was added at 10 weeks after seed germination. Sporophore formation was induced after 20 weeks of growth, and dikaryotic cultures were isolated from their tissue. Seedlings were harvested, and growth and mycorrhization were assessed. Levels of both were generally lower for T1-treated seedlings, compared with seedlings receiving D, while levels for T5-treated seedlings were intermediate. Sporophore genotype variability was assessed for inoculum treatments by using the isoenzymatic marker leucine aminopeptidase. The greatest genetic variability was seen with the basidiospore treatments T1 and T5, with up to four leucine aminopeptidase patterns per seedling. The mixed treatments D plus T1 and D plus T5 produced most frequently, but not exclusively, the inoculated dikaryon genotype. After isoenzyme results were assessed, variable sporophore isolates of mixed treatments were analyzed with randomly amplified polymorphic DNA and PCR mitochondrial DNA markers to determine if they were formed by dikaryon-monokaryon crosses between the inoculated dikaryon and monosporous mycelia.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7486997

The effect of a microgravity (space) environment on the expression of expansins from the peg and root tissues of Cucumis sativus

NASA Technical Reports Server (NTRS)

Link, B. M.; Wagner, E. R.; Cosgrove, D. J.

2001-01-01

In young cucumber seedlings, the peg is a polar outgrowth of tissue that functions by snagging the seed coat, thereby freeing the cotyledons. The development of the peg is thought to be gravity-dependent and has become a model system for plant-gravity response. Peg development requires rapid cell expansion, a process thought to be catalyzed by alpha-expansins, and thus was a good system to identify expansins that were regulated by gravity. This study identified 7 new alpha-expansin cDNAs from cucumber seedlings (Cucumis sativus L. cv Burpee Hybrid II) and examined their expression patterns. Two alpha-expansins (CsExp3 and CsExp4) were more highly expressed in the peg and the root. Earlier reports stated that pegs tend not to form in the absence of gravity, so the expression levels were compared in the pegs of seedlings grown in space (STS-95), on a clinostat, and on earth (1 g). Pegs were observed to form at high frequency on clinostat and space-grown seedlings, yet on clinostats there was more than a 4-fold reduction in the expression of CsExp3 in the pegs of seedlings grown on clinostats vs. those grown at 1 g, while the CsExp4 gene appeared to be turned off (below detection limits). There were no detectable differences in expansin gene expression levels for the pegs of seedlings grown in space or in the orbiter environmental simulator (OES) (1 g) at NASA. The microgravity environment did not affect the expression of CsExp3 or CsExp4, and the clinostat did not simulate the microgravity environment well.

Genetic Components of Heterosis for Seedling Traits in an Elite Rice Hybrid Analyzed Using an Immortalized F2 Population.

PubMed

Zhu, Dan; Zhou, Gang; Xu, Caiguo; Zhang, Qifa

2016-02-20

Utilization of heterosis has greatly contributed to rice productivity in China and many Asian countries. Superior hybrids usually show heterosis at two stages: canopy development at vegetative stage and panicle development at reproductive stage resulting in heterosis in yield. Although the genetic basis of heterosis in rice has been extensively investigated, all the previous studies focused on yield traits at maturity stage. In this study, we analyzed the genetic basis of heterosis at seedling stage making use of an "immortalized F2" population composed of 105 hybrids produced by intercrossing recombinant inbred lines (RILs) from a cross between Zhenshan 97 and Minghui 63, the parents of Shanyou 63, which is an elite hybrid widely grown in China. Eight seedling traits, seedling height, tiller number, leaf number, root number, maximum root length, root dry weight, shoot dry weight and total dry weight, were investigated using hydroponic culture. We analyzed single-locus and digenic genetic effects at the whole genome level using an ultrahigh-density SNP bin map obtained by population re-sequencing. The analysis revealed large numbers of heterotic effects for seedling traits including dominance, overdominance and digenic dominance (epistasis) in both positive and negative directions. Overdominance effects were prevalent for all the traits, and digenic dominance effects also accounted for a large portion of the genetic effects. The results suggested that cumulative small advantages of the single-locus effects and two-locus interactions, most of which could not be detected statistically, could explain the genetic basis of seedling heterosis of the F1 hybrid. Copyright © 2016 Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, and Genetics Society of China. Published by Elsevier Ltd. All rights reserved.

[Graviresponse in higher plants and its regulation in molecular bases: relevance to growth and development, and auxin polar transport in etiolated pea seedlings].

PubMed

Ueda, Junichi; Miyamoto, Kensuke

2003-08-01

We review the graviresponse under true and simulated microgravity conditions on a clinostat in higher plants, and its regulation in molecular bases, especially on the aspect of auxin polar transport in etiolated pea (Pisum sativum L. cv. Alaska) seedlings which were the plant materials subjected to STS-95 space experiments. True and simulated microgravity conditions substantially affected growth and development in etiolated pea seedlings, especially the direction of growth of stems and roots, resulting in automorphosis. In etiolated pea seedlings grown in space, epicotyls were the most oriented toward the direction far from the cotyledons, and roots grew toward the aerial space of Plant Growth Chamber. Automorphosis observed in space were well simulated by a clinorotation on a 3-dimensional clinostat and also phenocopied by the application of auxin polar transport inhibitors of 2,3,5-triiodobenzoic acid, N-(1-naphtyl)phthalamic acid and 9-hydroxyfluorene-9-carboxylic acid. Judging from the results described above together with the fact that activities of auxin polar transport in epicotyls of etiolated pea seedlings grown in space substantially were reduced, auxin polar transport seems to be closely related to automorphosis. Strenuous efforts to learn in molecular levels how gravity contributes to the auxin polar transport in etiolated pea epicotyls resulted in successful identification of PsPIN2 and PsAUX1 genes located in plasma membrane which products are considered to be putative efflux and influx carriers of auxin, respectively. Based on the results of expression of PsPIN2 and PsAUX1 genes under various gravistimulations, a possible role of PsPIN2 and PsAUX1 genes for auxin polar transport in etiolated pea seedlings will be discussed.

Demonstration of the economic feasibility of plant tissue culture for jojoba (Simmondsia chinensis) and Euphorbia spp

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sluis, C.

1980-09-01

The economic feasibility of plant tissue culture was demonstrated as applied to two plants: jojoba (Simmondsia chinensis) and Euphorbia spp. The gopher weed (Euphorbia lathyris) was selected as the species of Euphorbia to research due to the interest in this plant as a potential source of hydrocarbon-like compounds. High yield female selections of jojoba were chosen from native stands and were researched to determine the economic feasibility of mass producing these plants via a tissue culture micropropagation program. The female jojoba selection was successfully mass produced through tissue culture. Modifications in initiation techniques, as well as in multiplication media andmore » rooting parameters, were necessary to apply the tissue culture system, which had been developed for juvenile seedling tissue, to mature jojobas. Since prior attempts at transfer of tissue cultured plantlets were unsuccessful, transfer research was a major part of the project and has resulted in a system for transfer of rooted jojoba plantlets to soil. Euphorbia lathyris was successfully cultured using shoot tip cultures. Media and procedures were established for culture initiation, multiplication of shoots, callus induction and growth, and root initiation. Well-developed root systems were not attained and root initiation percentages should be increased if the system is to become commercially feasible.« less

Development of spruce-fir stands following spruce beetle outbreaks

Treesearch

J. M. Schmid; T. E. Hinds

1974-01-01

Logged and unlogged stands of Engelmann spruce-subalpine fir were evaluated in spruce beetle outbreak areas infested about 15, 25, 50, and 100 years ago. Seedling regeneration was generally adequate except in heavily logged areas, although seedlings were often damaged, apparently by animals. Species composition was dramatically altered in favor of fir in the unlogged...

Understanding sucrose metabolism and growth in a developing sweetgum plantation.

Treesearch

Shi-Jean S. Sung; Paul P. Kormanik; C.C. Black

1994-01-01

Stem diameter growth of 9-year-old sweetgum (Liquidambar styraciflua) trees was measured and related with the activity of sucrose synthase (SS), an enzyme that has been associated with carbon sink strength in agriculture crops and tree seedlings. In 1984, 10 sweetgum seedlings were transplanted to control plots and plots amended with sewage sludge or nitorgen and...

Is seedling grading beneficial to artificial regeneration of northern red oaks?

Treesearch

Paul P. Kormanik; Shi-Jean S. Sung; Stanley J. Zarnoch

2005-01-01

Effective and consistent success with artificial regeneration of northern red oak (Quercus rubra L.) has been achieved on many sites using 1-0 graded seedlings produced with the nursery protocol developed by the USDA Forest Service at the Institute of Tree Root Biology in cooperation with the Georgia Forestry Commission. Small northern red oak (NRO)...

Seasonal ectomycorrhizal fungal biomass development on loblolly pine (Pinus taeda L.) seedlings

Treesearch

Shi-Jean S. Sung; L.M. White; D.H. Marx; W.J. Otrosina

1995-01-01

Ergosterol, a membrane sterol found in fungi but not in plants, was used to estimate live mycelia biomass in ectomycorrhizae. Loblolly pine (Pinus taeda L.) seeds were sown in April 1993 and grown with standard nursery culture ractices. Correlations between total seedling ergosterol and visual assessment of mycorrhizal colonization were high during...

Prescribed fire and oak seedling development in an Appalachian forest

Treesearch

Jacob Royse; Mary Arthur; David Loftis

2009-01-01

In recent decades considerable research has focused on the use of prescribed fire in oak-dominated forests with the management objective of promoting oak regeneration for future overstory dominance. These studies typically focus on the response of oak seedlings and saplings already in place when experimental prescribed fires are set because it is difficult to time...

Germination and seedling establishment of spiny hopsage in response to planting date and seedbed environment

Treesearch

Nancy L. Shaw; Marshall R. Haferkamp; Emerenciana G. Hurd

1994-01-01

Reestablishment of spiny hopsrge (Grayia spinosa [Hook.] Moq.) in the shrub steppe requires development of appropriate seeding technology. We examined the effect of planting date and seedbed environment on germination and seedling establishment of 2 seed sources at 2 southwestern Idaho sites. Seedbeds were prepared by rototilling. In 1987-88, seeds...

Developing regeneration in woodlots at Gettysburg National Military Park

Treesearch

Todd W. Bowersox; Gerald L. Storm; Walter M. Tzilkowski

1993-01-01

Woodlots are significant features of the historic scene at Gettysburg National Military Park, Pennsylvania. Recent inventories of these historic woodlots indicated a general lack of seedling recruitment in the uneven-aged stands with a mature mixed oak overstory and a midstory of ash-cherry-dogwood-hickory. Seedling-sized stems of shrub and tree species were abundant,...

Potting Media Affect Growth and Disease Development of Container-Grown Southern Pines

Treesearch

William H. Pawuk

1981-01-01

Longleaf pine (Pinus palustris Mill.) and shortleaf pine (P. echinata Mill.) seedlings grew best in equal parts of peat and vermiculite with a low pH. Seedlings grew better in shredded pine cone media than pine bark media. Growth increased when soil or vermiculite was added to cone or bark chips. Commercial bark-vermiculite...

Measuring Tree Seedlings and Associated Understory Vegetation in Pennsylvania's Forests

Treesearch

William H. McWilliams; Todd W. Bowersox; Patrick H. Brose; Daniel A. Devlin; James C. Finley; Kurt W. Gottschalk; Steve Horsley; Susan L. King; Brian M. LaPoint; Tonya W. Lister; Larry H. McCormick; Gary W. Miller; Charles T. Scott; Harry Steele; Kim C. Steiner; Susan L. Stout; James A. Westfall; Robert L. White

2005-01-01

The Northeastern Research Station's Forest Inventory and Analysis (NE-FIA) unit is conducting the Pennsylvania Regeneration Study (PRS) to evaluate composition and abundance of tree seedlings and associated vegetation. Sampling methods for the PRS were tested and developed in a pilot study to determine the appropriate number of 2-m microplots needed to capture...

Strategies and challenges for nursery production: Perspectives on where we're going and where we've been

Treesearch

Diane L. Haase

2010-01-01

During the past century, seedling production has changed in accordance with technology and new knowledge. Many strategies have been developed to address challenges associated with pests, environmental conditions, and customer demands. Although the underlying concepts for growing seedlings have remained relatively constant, technological advances have enabled nurseries...

Effects of hayscented fern density and light on white ash seedling growth

Treesearch

Tracy E. Hippensteel; Todd W. Bowersox

1995-01-01

Communities of hayscented ferns [Dennstaedtia punctilobula (Michx.) Moore] are present in many forested areas of Pennsylvania. These ferns can reduce the number and height growth of desirable tree seedlings. A study was conducted to determine the effects of fern frond density on the stem growth and leaf development of bare-root planted white ash (...

Characterization of the snowy cotyledon 1 mutant of Arabidopsis thaliana: the impact of chloroplast elongation factor G on chloroplast development and plant vitality.

PubMed

Albrecht, Verónica; Ingenfeld, Anke; Apel, Klaus

2006-03-01

During seedling development chloroplast formation marks the transition from heterotrophic to autotrophic growth. The development and activity of chloroplasts may differ in cotyledons that initially serve as a storage organ and true leaves whose primary function is photosynthesis. A genetic screen was used for the identification of genes that affect selectively chloroplast function in cotyledons of Arabidopsis thaliana. Several mutants exhibiting pale cotyledons and green true leaves were isolated and dubbed snowy cotyledon (sco). One of the mutants, sco1, was characterized in more detail. The mutated gene was identified using map-based cloning. The mutant contains a point mutation in a gene encoding the chloroplast elongation factor G, leading to an amino acid exchange within the predicted 70S ribosome-binding domain. The mutation results in a delay in the onset of germination. At this early developmental stage embryos still contain undifferentiated proplastids, whose proper function seems necessary for seed germination. In light-grown sco1 seedlings the greening of cotyledons is severely impaired, whereas the following true leaves develop normally as in wild-type plants. Despite this apparent similarity of chloroplast development in true leaves of mutant and wild-type plants various aspects of mature plant development are also affected by the sco1 mutation such as the onset of flowering, the growth rate, and seed production. The onset of senescence in the mutant and the wild-type plants occurs, however, at the same time, suggesting that in the mutant this particular developmental step does not seem to suffer from reduced protein translation efficiency in chloroplasts.

Urban environment of New York City promotes growth in northern red oak seedlings.

PubMed

Searle, Stephanie Y; Turnbull, Matthew H; Boelman, Natalie T; Schuster, William S F; Yakir, Dan; Griffin, Kevin L

2012-04-01

Urbanization is accelerating across the globe, elevating the importance of studying urban ecology. Urban environments exhibit several factors affecting plant growth and function, including high temperatures (particularly at night), CO(2) concentrations and atmospheric nitrogen deposition. We investigated the effects of urban environments on growth in Quercus rubra L. seedlings. We grew seedlings from acorns for one season at four sites along an urban-rural transect from Central Park in New York City to the Catskill Mountains in upstate New York (difference in average maximum temperatures of 2.4 °C; difference in minimum temperatures of 4.6 °C). In addition, we grew Q. rubra seedlings in growth cabinets (GCs) mimicking the seasonal differential between the city and rural sites (based on a 5-year average). In the field experiment, we found an eightfold increase in biomass in urban-grown seedlings relative to those grown at rural sites. This difference was primarily related to changes in growth allocation. Urban-grown seedlings and seedlings grown at urban temperatures in the GCs exhibited a lower root: shoot ratio (urban ~0.8, rural/remote ~1.5), reducing below-ground carbon costs associated with construction and maintenance. These urban seedlings instead allocated more growth to leaves than did rural-grown seedlings, resulting in 10-fold greater photosynthetic area but no difference in photosynthetic capacity of foliage per unit area. Seedlings grown at urban temperatures in both the field and GC experiments had higher leaf nitrogen concentrations per unit area than those grown at cooler temperatures (increases of 23% in field, 32% in GC). Lastly, we measured threefold greater (13)C enrichment of respired CO(2) (relative to substrate) in urban-grown leaves than at other sites, which may suggest greater allocation of respiratory function to growth over maintenance. It also shows that lack of differences in total R flux in response to environmental conditions may mask dramatic shifts in respiratory functioning. Overall, our findings indicating greater seedling growth and establishment at a critical regeneration phase of forest development may have important implications for the ecology of urban forests as well as the predicted growth of the terrestrial biosphere in temperate regions in response to climate change.

Effects of open-field experimental warming on the growth of two-year-old Pinus densiflora and Abies holophylla seedlings

NASA Astrophysics Data System (ADS)

Han, S.; Son, Y.; Lee, S.; Jo, W.; Yoon, T.; Park, C.; Ko, S.; Kim, J.; Han, S.; Jung, Y.

2012-12-01

Temperature increase due to climate change is expected to affect tree growth and distribution [Way and Oren, 2010]. The responses of trees to warming vary with tree species, ontogenic stages, tree life forms, and biomes. Especially, seedling stage is a vulnerable period for tree survival and competition [Saxe et al., 2007] and thus research on effects of temperature increase on seedling stage is needed. We aimed to examine the responses of coniferous seedlings to future temperature increase by conducting an open-field warming experiment. An experimental warming set-up using infra-red heater was built in 2011 and the temperature in warming plots has been regulated to 3°C higher than that of control plots constantly. The seeds of Pinus densiflora and Abies holophylla were planted in each 1 m × 1 m plot (n=3) in April, 2012. Seedling growth, root collar diameter (RCD) and height of 45 individuals of each plot were measured in June and July, 2012. The survival rate of seedlings was also measured. Survival rate of P. densiflora was lower in warming plots (93.3%) than in control plots (100.0%, p<0.05) and that of A. holophylla was also decreased in warming plots (79.3%) than in control plots (97.0%, p<0.01). RCD and height of P. densiflora seedlings were not significantly different between control and warming plots, however, height of A. holophylla was significantly higher in warming plots in June and July (p<0.01). Comparatively, RCD of A. holophylla was only higher in control plots in June. While there is still a lack of case studies on the growth of seedlings under experimental warming, a few studies reported increased seedling growth [Yin et al., 2008] or and no difference [Han et al., 2009] in warming plots. Different responses of seedling growth between two species of the current study might be derived from species-specific acclimation to temperature increase and/or other limiting factors [Way and Oren, 2010]. This result is, to our knowledge, unprecedented and will contribute to the knowledge of species-specific growth response of tree species and to development of model predicting species distribution in future climate regime. Future work on physiological traits of seedlings and analysis on environmental factors will provide mechanism of seedling response to increased temperature. [This work was supported by 'Korea Forest Service (S111112L080110)'.

Deployment of deer-resistant western redcedar (Thuja plicata)

Treesearch

John Russell

2008-01-01

Protecting planted western redcedar (Thuja plicata) seedlings from deer browse in the Pacific Northwest and British Columbia is estimated to cost up to CAN$ 25 million annually. Recent studies linking deer browse and needle monoterpenes has resulted in the initiation of a breeding program for deer-resistant western redcedar at Cowichan Lake Research...

Accuracy of regeneration surveys in New England northern hardwoods

Treesearch

William B. Leak

2007-01-01

Four 5-ac demonstration harvests were initiated in 1951 on the Bartlett Experimental Forest, New Hampshire: light selection, moderate selection, diameter limit, and liquidation. In 1952 and 1959, regeneration surveys were conducted that measured several different attributes of the seedlings and saplings in the cutover stands. In 2005, the stands were remeasured to...

How Are Investment Returns Affected By Competition Control and Southern Oak Seedling Survival?

Treesearch

Donald L. Grebner; Andrew W. Ezell; Deborah A. Gaddis; Steven H. Bullard

2004-01-01

Increasing numbers of landowners are establishing hardwood plantations to satisfy their management objectives. Despite a dearth of research on competition control and its effects on initial hardwood plantation survival and investment returns, this study examines alternative competition control regimes for southern oak establishment. The analysis includes estimates of...

EFFECTS OF CO2 AND O3 IN PONDEROSA PINE PLANT/LITTER/SOIL MESOCOSMS

EPA Science Inventory

Forested ecosysems are subjected to interacting conditions whose joint impacts may be quite different from those from single factors. To understand the impacts of CO2 and O3 on forest ecosystems, in April 1998, we initiated a four-year study of a Ponderosa pine seedling/soil/lit...

Some Growth Aspects of Seymeria cassioicies

Treesearch

Charles M. Stangle; Lytton J. Musselman

1981-01-01

The root parasite, Seymeria cassioides, will not initiate height growth without attachment to a host root when grown under normal fertility conditions, although the seedling may remain alive for 40 days or more without a host. During this time the roots elongate markedly. Fresh pine root segments do not influence the direction of root growth. Although S....

Genetic control of phyllotaxy phase shift in juvenile vines in a rootstock hybrid population

USDA-ARS?s Scientific Manuscript database

Grapevine seedlings initially display spiral phyllotaxy of true leaves, then undergo a shift to alternate phyllotaxy with the production of the first lateral meristems (typically tendrils). The node at which the shift from spiral to alternate phyllotaxy occurs varies from about the 4th to about the...

Control of Lophodermium needlecast disease in nurseries and Christmas tree plantations.

Treesearch

Thomas H. Nicholls; Darroll D. Skilling

1974-01-01

Recommendations are based upon studies initiated by the USDA Forest Service as a result of an outbreak of Lophodermium needlecast in several nurseries in the Lake States that spread to plantations throughout the United States due, in part, to shipment of diseased seedlings during the late 1960's and early 1970's.

Physiological characteristics of tropical rain forest tree species: a basis for the development of silvicultural technology.

PubMed

Sasaki, Satohiko

2008-01-01

The physiological characteristics of the dominant tree species in the tropical rain forest mainly belonging to dipterocarps as well as the environmental conditions especially for the light in the forest were studied to establish the silvicultural system for the forest regeneration in the tropical South Asia. The flowering patterns of the dipterocarp trees are usually irregular and unpredictable, which make difficult to collect sufficient seeds for raising the seedlings. The field survey revealed the diverged features of the so-called gregarious or simultaneous flowering of various species of this group. Appropriate conditions and methods for the storage of the seeds were established according to the detailed analyses of the morphological and physiological characteristics of the seeds such as the low temperature tolerance and the moisture contents. The intensity and spectra of the light in the forest primarily determine the growth and the morphological development of the seedlings under the canopy. Based on the measurements of the diffused light at the sites in the tropical forest in the varying sunlight, the parameters such as "the steady state of the diffuse light" and "the turning point" were defined, which were useful to evaluate the light conditions in the forest. To improve the survival of the transplanted seedlings, a planting method of "the bare-root seedlings", the seedlings easy to be handled by removal of all leaves, soil and pots, was developed. Its marked efficiency was proved with various dipterocarps and other tropical trees by the field trial in the practical scale. Tolerance of the various species to the extreme environmental conditions such as fires, acid soils and drought were examined by the experiments and the field survey, which revealed marked adaptability of Shorea roxburghii as a potential species for regeneration of the tropical forests.

Heterosis in Rice Seedlings: Its Relationship to Gibberellin Content and Expression of Gibberellin Metabolism and Signaling Genes1[W][OA

PubMed Central

Ma (马谦), Qian; Hedden, Peter; Zhang (张启发), Qifa

2011-01-01

Despite the accumulation of data on the genetic and molecular understanding of heterosis, there is little information on the regulation of heterosis at the physiological level. In this study, we performed a quantitative analysis of endogenous gibberellin (GA) content and expression profiling of the GA metabolism and signaling genes to investigate the possible relationship between GA signaling and heterosis for seedling development in rice (Oryza sativa). The materials used were an incomplete diallele set of 3 × 3 crosses and the six parents. In the growing shoots of the seedlings at 20 d after sowing, significant positive correlations between the contents of some GA species and performance and heterosis based on shoot dry mass were detected. Expression analyses of GA-related genes by real-time reverse transcription-polymerase chain reaction revealed that 13 out of the 16 GA-related genes examined exhibited significant differential expression among the F1 hybrid and its parents, acting predominantly in the modes of overdominance and positive dominance. Expression levels of nine genes in the hybrids displayed significant positive correlations with the heterosis of shoot dry mass. These results imply that GAs play a positive role in the regulation of heterosis for rice seedling development. In shoots plus root axes of 4-d-old germinating seeds that had undergone the deetiolation, mimicking normal germination in soil, the axis dry mass was positively correlated with the content of GA29 but negatively correlated with that of GA19. Our findings provide supporting evidence for GAs playing an important regulatory role in heterosis for rice seedling development. PMID:21693671

Effect of a transpiration retardant on survival of planted ponderosa pine.

Treesearch

Edwin L. Mowat

1961-01-01

Losses of newly planted coniferous seedlings from drought during the critical period when new roots are developing is a continuing problem in many parts of the West. One possible solution frequently suggested to forest managers is to coat the seedling tops with a transpiration inhibitor, usually a waxy substance applied in emulsion form. This research note gives the...

Shoot growth and heterophylly in Acer

Treesearch

William B. Critchfield

1971-01-01

In Acer and many other woody genera, leaf form changes drastically and often abruptly during the life of the plant. Heterophylly is of two principal kinds in these woody plants: (1) changes during seedling and post-seedling stages, and (2) changes during the development of single annual shoots of adult plants. Type (1) is ubiquitous in Acer] type (2) is a regular...

Recovery of a bearclover (Chamaebatia foliolosa) plant community after site preparation and planting of ponderosa pine seedlings

Treesearch

Philip M. McDonald; Gary O. Fiddler

1999-01-01

Bearclover inhabits thousands of acres of forest land in northern and central California, but little quantification of its recovery after timber harvest, site preparation, and planting is available. And the species composition and development of the ensuing plant community is largely unknown. Density, foliar cover, and height of planted ponderosa pine seedlings,...

Advanced Oak Seedling Development as Influenced by Shelterwood Treatments, Competition Control, Deer Fencing, and Prescribed Fire

Treesearch

Gary W. Miller; Patrick H. Brose; Kurt W. Gottschalk

2017-01-01

Advanced northern red oak (Quercus rubra) seedlings in an 85-year-old forest located in north-central Pennsylvania were observed for 10 years after manipulation of available sunlight by shelterwood treatments, reduction of interfering plants by broadcast herbicides and/or a single prescribed fire, and reduction of deer damage by fencing. Twenty-...

Episodic growth and relative shoot:root balance in loblolly pine seedlings

Treesearch

A.P. Drew; F. Thomas Ledig

1980-01-01

Leaf, root and stem systems of loblolly pine seedlings are characterized by a seasonal periodicity in growth, during which they alternate in spurts of activity. Despite this periodicity, the allometric coefficient describing the ratio of the relative growth rates of leaf to root remains constant for at least the first two years of development. In part, constancy...

Developing a field facility for evaluating flood tolerance of hardwood seedlings and understory ground covers

Treesearch

J.W. Van Sambeek; Robert L. McGraw; John M. Kabrick; Mark V. Coggeshall; Irene M. Unger; Daniel C. Dey

2007-01-01

Information about the flood tolerance of most plants has been obtained from either observations following natural floods or pot studies with amended soils. To better evaluate and compare flood tolerance among hardwood seedlings and ground covers for use in riparian buffer and bottomland plantings, a large outdoor facility with natural floodplain soils is needed where...

The visibility of using water boxes and mulch in dryland revegetation

NASA Astrophysics Data System (ADS)

Alhamad, Mohammad Noor; Alrababah, Mohammad; Athamneh, Hanaa

2017-04-01

Drylands cover more than 41% of the world's surface area and are homeland for about one-third of the world's population, 90% of them in developing countries. Land degradation in the drylands is hot environmental topic as it impacts environmental quality and jeopardizes food security in developing countries. The climate of Jordan varies from dry sub-humid Mediterranean in northwestern areas to desert conditions over a distance of 100 km, where more than 90 % of the county's area receives annual rainfall of less than 200 mm. In Jordan revegetation programs are rainfed; rainfall in Jordan is characterized by variable nature, thus, these programs faces a major challenge of the low survival rate of transplanted seedlings. The present study ought to explore the visibility of using water boxes and plastic mulch as an innovative approach to enhance seedling survival and establishment of four forest tress species ( Carob, Cupressus, Quercus, and Pinus). The experiment results showed that Cupressus, and Pinus seedlings expressed the highest survival rate of 88% and 84 % respectively, flowed by Crob (64%) and Querrcus (16%). The plastic mulch significantly enhanced the seedling survival rate b y40 % over the control while the water boxes resulted in an increase of 32 % over the control.

Temporal changes in fungal communities from buckwheat seeds and their effects on seed germination and seedling secondary metabolism.

PubMed

Kovačec, Eva; Likar, Matevž; Regvar, Marjana

2016-05-01

Seed-associated fungal communities affect multiple parameters of seed quality at all stages of production, from seed development to post-harvest storage and germination. We therefore investigated the diversity and dynamics of fungal communities in the seeds of common buckwheat (Fagopyrum esculentum) and Tartary buckwheat (F. tataricum) from harvest to 1 y of storage. Fungal populations in seeds were relatively stable, comprised mainly of field fungi. Incidence of fungi was most likely determined by fungal interspecies direct interactions, as well as by their synthesis of volatile organic compounds. Most prominent antagonistic interactions were seen for two plant pathogens, Alternaria alternata on Botrytis cinerea. Detrimental effects of the fungi on seed germination and seedling development were related to fungal extracellular enzyme activity, and in particular to amylase, cellulase and, polyphenol oxidase. Polyphenol and tannin concentrations in buckwheat seedlings were related to fungal growth rate and intensity of fungal cellulase activity, respectively, which suggests that physical penetration of the fungi through the host tissues is probably the stimulus for the activation of plant defence reactions in these seedlings. Copyright © 2016 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Organ-coordinated response of early post-germination mahogany seedlings to drought.

PubMed

Horta, Lívia P; Braga, Márcia R; Lemos-Filho, José P; Modolo, Luzia V

2014-04-01

Water deficit tolerance during post-germination stages is critical for seedling recruitment. In this work, we studied the effect of water deficit on morphological and biochemical responses in different organs of newly germinated mahogany (Swietenia macrophylla King) seedlings, a woody species that occurs in the Amazon rainforest. The root : shoot ratio increased under water deficit. The leaf number and water potential were not altered, although reductions in leaf area and stomatal conductance were observed. Osmotic potential became more negative in leaves of seedlings under severe stress. Water deficit increased fructose, glucose, sucrose and myo-inositol levels in leaves. Stems accumulated fructose, glucose and l-proline. Nitric oxide (NO) levels increased in the vascular cylinder of roots under severe stress while superoxide anion levels decreased due to augmented superoxide dismutase activity in this organ. Water deficit induced glutathione reductase activity in both roots and stems. Upon moderate or severe stress, catalase activity decreased in leaves and remained unaffected in the other seedling organs, allowing for an increase of hydrogen peroxide (H2O2) levels in leaves. Overall, the increase of signaling molecules in distinct organs-NO in roots, l-proline in stems and H2O2 and myo-inositol in leaves-contributed to the response of mahogany seedlings to water deficit by triggering biochemical processes that resulted in the attenuation of oxidative stress and the establishment of osmotic adjustment. Therefore, this body of evidence reveals that the development of newly germinated mahogany seedlings may occur in both natural habitats and crop fields even when water availability is greatly limited.

Sorghum Landrace Collections from Cooler Regions of the World Exhibit Magnificent Genetic Differentiation and Early Season Cold Tolerance.

PubMed

Maulana, Frank; Weerasooriya, Dilooshi; Tesso, Tesfaye

2017-01-01

Cold temperature is an important abiotic stress affecting sorghum production in temperate regions. It reduces seed germination, seedling emergence and seedling vigor thus limiting the production of the crop both temporally and spatially. The objectives of this study were (1) to assess early season cold temperature stress response of sorghum germplasm from cooler environments and identify sources of tolerance for use in breeding programs, (2) to determine population structure and marker-trait association among these germplasms for eventual development of marker tools for improving cold tolerance. A total of 136 sorghum accessions from cooler regions of the world were phenotyped for seedling growth characteristics under cold temperature imposed through early planting. The accessions were genotyped using 67 simple sequence repeats markers spanning all ten linkage groups of sorghum, of which 50 highly polymorphic markers were used in the analysis. Genetic diversity and population structure analyses sorted the population into four subpopulations. Several accessions distributed in all subpopulations showed either better or comparable level of tolerance to the standard cold tolerance source, Shan qui red. Association analysis between the markers and seedling traits identified markers Xtxp 34, Xtxp 88, and Xtxp 319 as associated with seedling emergence, Xtxp 211 and Xtxp 304 with seedling dry weight, and Xtxp 20 with seedling height. The markers were detected on chromosomes previously found to harbor QTLs associated with cold tolerance in sorghum. Once validated these may serve as genomic tools in marker-assisted breeding or for screening larger pool of genotypes to identify additional sources of cold tolerance.

Sorghum Landrace Collections from Cooler Regions of the World Exhibit Magnificent Genetic Differentiation and Early Season Cold Tolerance

PubMed Central

Maulana, Frank; Weerasooriya, Dilooshi; Tesso, Tesfaye

2017-01-01

Cold temperature is an important abiotic stress affecting sorghum production in temperate regions. It reduces seed germination, seedling emergence and seedling vigor thus limiting the production of the crop both temporally and spatially. The objectives of this study were (1) to assess early season cold temperature stress response of sorghum germplasm from cooler environments and identify sources of tolerance for use in breeding programs, (2) to determine population structure and marker-trait association among these germplasms for eventual development of marker tools for improving cold tolerance. A total of 136 sorghum accessions from cooler regions of the world were phenotyped for seedling growth characteristics under cold temperature imposed through early planting. The accessions were genotyped using 67 simple sequence repeats markers spanning all ten linkage groups of sorghum, of which 50 highly polymorphic markers were used in the analysis. Genetic diversity and population structure analyses sorted the population into four subpopulations. Several accessions distributed in all subpopulations showed either better or comparable level of tolerance to the standard cold tolerance source, Shan qui red. Association analysis between the markers and seedling traits identified markers Xtxp34, Xtxp88, and Xtxp319 as associated with seedling emergence, Xtxp211 and Xtxp304 with seedling dry weight, and Xtxp20 with seedling height. The markers were detected on chromosomes previously found to harbor QTLs associated with cold tolerance in sorghum. Once validated these may serve as genomic tools in marker-assisted breeding or for screening larger pool of genotypes to identify additional sources of cold tolerance. PMID:28536596

The role of onion-associated fungi in bulb mite infestation and damage to onion seedlings.

PubMed

Ofek, Tal; Gal, Shira; Inbar, Moshe; Lebiush-Mordechai, Sara; Tsror, Leah; Palevsky, Eric

2014-04-01

In Israel Rhizoglyphus robini is considered to be a pest in its own right, even though the mite is usually found in association with fungal pathogens. Plant protection recommendations are therefore to treat germinating onions seedlings, clearly a crucial phase in crop production, when mites are discovered. The aim of this study was to determine the role of fungi in bulb mite infestation and damage to germinating onion seedlings. Accordingly we (1) evaluated the effect of the mite on onion seedling germination and survival without fungi, (2) compared the attraction of the mite to species and isolates of various fungi, (3) assessed the effect of a relatively non-pathogenic isolate of Fusarium oxysporum on mite fecundity, and (4) determined the effects of the mite and of F. oxysporum separately and together, on onion seedling germination and sprout development. A significant reduction of seedling survival was recorded only in the 1,000 mites/pot treatment, after 4 weeks. Mites were attracted to 6 out of 7 collected fungi isolates. Mite fecundity on onion sprouts infested with F. oxysporum was higher than on non-infested sprouts. Survival of seedlings was affected by mites, fungi, and their combination. Sprouts on Petri dishes after 5 days were significantly longer in the control and mite treatments than both fungi treatments. During the 5-day experiment more mites were always found on the fungi-infected sprouts than on the non-infected sprouts. Future research using suppressive soils to suppress soil pathogens and subsequent mite damage is proposed.

Genome Wide Association Study of Seedling and Adult Plant Leaf Rust Resistance in Elite Spring Wheat Breeding Lines

PubMed Central

Gao, Liangliang; Turner, M. Kathryn; Chao, Shiaoman; Kolmer, James; Anderson, James A.

2016-01-01

Leaf rust is an important disease, threatening wheat production annually. Identification of resistance genes or QTLs for effective field resistance could greatly enhance our ability to breed durably resistant varieties. We applied a genome wide association study (GWAS) approach to identify resistance genes or QTLs in 338 spring wheat breeding lines from public and private sectors that were predominately developed in the Americas. A total of 46 QTLs were identified for field and seedling traits and approximately 20–30 confer field resistance in varying degrees. The 10 QTLs accounting for the most variation in field resistance explained 26–30% of the total variation (depending on traits: percent severity, coefficient of infection or response type). Similarly, the 10 QTLs accounting for most of the variation in seedling resistance to different races explained 24–34% of the variation, after correcting for population structure. Two potentially novel QTLs (QLr.umn-1AL, QLr.umn-4AS) were identified. Identification of novel genes or QTLs and validation of previously identified genes or QTLs for seedling and especially adult plant resistance will enhance understanding of leaf rust resistance and assist breeding for resistant wheat varieties. We also developed computer programs to automate field and seedling rust phenotype data conversions. This is the first GWAS study of leaf rust resistance in elite wheat breeding lines genotyped with high density 90K SNP arrays. PMID:26849364

Walnut Twig Beetle (Coleoptera: Curculionidae: Scolytinae) Colonization of Eastern Black Walnut Nursery Trees

PubMed Central

Klingeman, William E.; Mayfield, Albert; Myers, Scott; Taylor, Adam

2017-01-01

Thousand cankers disease, caused by the invasive bark beetle Pityophthorus juglandis Blackman and an associated fungal pathogen Geosmithia morbida M.Kolařík, E. Freeland, C. Utley, N. Tisserat, currently threatens the health of eastern black walnut (Juglans nigra L.) in North America. Both the beetle and pathogen have expanded beyond their native range via transport of infested walnut wood. Geosmithia morbida can develop in seedlings following inoculation, but the ability of P. juglandis to colonize young, small diameter trees has not been investigated. This study assessed the beetle’s colonization behavior on J. nigra nursery trees. Beetles were caged directly onto the stems of walnut seedlings from five nursery sources representing a range of basal stem diameter classes. Seedlings were also exposed to P. juglandis in a limited choice, field-based experiment comparing pheromone-baited and unbaited stems. When beetles were caged directly onto stems, they probed and attempted to colonize seedlings across the range of diameters and across sources tested, including stems as small as 0.5 cm in diameter. In the field experiment, beetles only attempted to colonize seedlings that were baited with a pheromone lure and appeared to prefer (though not statistically significant) the larger diameter trees. Despite several successful penetrations into the phloem, there was no evidence of successful progeny development within the young trees in either experiment. Further investigation is recommended to better elucidate the risk nursery stock poses as a pathway for thousand cankers disease causal organisms. PMID:28973569

Development-specific responses to drought stress in Aleppo pine (Pinus halepensis Mill.) seedlings.

PubMed

Alexou, Maria

2013-10-01

Aleppo pine (Pinus halepensis Mill.) is a pioneer species, highly competitive due to exceptional resistance to drought. To investigate the stress resistance in the first and second year of development, a steady-state drought experiment was implemented. Photosynthesis (A(net)), stomatal conductance and transpiration (E) were measured on three different sampling dates together with phloem soluble sugars, amino acids and non-structural proteins. Needle ascorbic acid (AsA) and reactive oxygen species were measured to evaluate the seedlings' drought stress condition in the final sampling. Drought impaired A(net) and E by 35 and 31%, respectively, and increased AsA levels up to 10-fold, without significant impact on the phloem metabolites. Phloem sugars related to temperature fluctuations rather than soil moisture and did not relate closely to A(net) levels. Sugars and proteins decreased between the second and third sampling date by 56 and 61%, respectively, and the ratio of sugars to amino acids decreased between the first and third sampling by 81%, while A(net) and water-use efficiency (A(net)/E) decreased only in the older seedlings. Although gas exchange was higher in the older seedlings, ascorbic acid and phloem metabolites were higher in the younger seedlings. It was concluded that the drought stress responses depended significantly on developmental stage, and research on the physiology of Aleppo pine regeneration should focus more on temperature conditions and the duration of drought than its severity.

Development of negative feedback during successive growth cycles of black cherry.

PubMed Central

Packer, Alissa; Clay, Keith

2004-01-01

Negative feedback between plant and soil microbial communities can be a key determinant of vegetation structure and dynamics. Previous research has shown that negative feedback between black cherry (Prunus serotina) and soil pathogens is strongly distance dependent. Here, we investigate the temporal dynamics of negative feedback. To examine short-term changes, we planted successive cycles of seedlings in the same soil. We found that seedling mortality increased steadily with growth cycle when sterile background soil was inoculated with living field soil but not in controls inoculated with sterilized field soil. To examine long-term changes, we quantified negative feedback across successive growth cycles in soil inoculated with living field soil from a mature forest system (more than 70 years old) versus a younger successional site (ca. 25 years old). In both cases negative feedback developed similarly. Our results suggest that negative feedback can develop very quickly in forest systems, at the spatial scale of a single seedling. PMID:15058444

Evaluations of plastic mesh tubes for protecting conifer seedling from pocket gophers in three western states

USGS Publications Warehouse

Engeman, Richard M.; Anthony, Richard M.; Barnes, Victor G.; Krupa, Heather W.; Evans, James

1999-01-01

The efficacy of plastic mesh tubes for protecting conifer seedlings from pocket gopher damage was evaluated on three national forest lands in three states. In each area, cohorts of 640 protected seedlings and 640 unprotected seedlings (3,840 total) were individually monitored for damage, survival, and growth twice each summer for 5 yr after planting. Substantial differences were found between protected and unprotected seedlings for time until occurrence of damage, survival time, proportion damaged and proportion surviving, as well as differences in growth. Over the three forest study sites, the proportion of unprotected seedlings damaged ranged from 60-89%, whereas the proportion of protected seedlings damaged after 5 yr ranged from 18-27%. The proportion of unprotected seedlings that died of gopher damage over 5 yr ranged from 46-64%, versus 1-19% for protected seedlings. Height growth was 25% greater for protected seedlings. Even when only undamaged seedlings were considered, protected seedlings exhibited superior height growth, possibly due to a more favorable microclimate provided by the tubes. These results were reflected in the higher and more uniform stocking rates for protected seedlings.

The stress protein level under clinorotation in context of the seedling developmental program and the stress response

NASA Astrophysics Data System (ADS)

Kozeko, Lyudmyla; Kordyum, Elizabeth

2006-09-01

Heat-shock proteins (HSP70 and HSP90) are present in plant cells under the normal growth conditions. At the same time, a variety of environmental disruptions results in their rapid synthesis as a substantial part of adaptation. HSP amounts can be indicative of a cellular stress level. Altered gravity (clinorotation) is unnatural for plants, so it may be a kind of stress. The aim of this study was to analyze the influence of horizontal clinorotation on the HSP70 and HSP90 level during seedling development. Pea (Pisum sativum L.) seedlings grown for 3 days from seed imbibitions in stationary control and under slow clinorotation (2 rpm) are used for this investigation. Western blot analysis indicated that HSP70 and HSP90 were abundant in the embryos of dry seeds and their amount decreased significantly during seed germination. But under horizontal clinorotation, their level in seedlings remained higher compared to the control. Furthermore, a comparison of the influence of horizontal and vertical clinorotation on the HSP level was carried out. On the ELISA data, HSP70 and HSP90 amounts in the 3-day old seedlings were higher after horizontal clinorotation than after vertical. The obtained data show an increased HSP70 and HSP90 level in pea seedlings under clinorotation. Both, rotation and change in the cell position relatively to a gravity vector affect the HSP level.

Root architecture simulation improves the inference from seedling root phenotyping towards mature root systems.

PubMed

Zhao, Jiangsan; Bodner, Gernot; Rewald, Boris; Leitner, Daniel; Nagel, Kerstin A; Nakhforoosh, Alireza

2017-02-01

Root phenotyping provides trait information for plant breeding. A shortcoming of high-throughput root phenotyping is the limitation to seedling plants and failure to make inferences on mature root systems. We suggest root system architecture (RSA) models to predict mature root traits and overcome the inference problem. Sixteen pea genotypes were phenotyped in (i) seedling (Petri dishes) and (ii) mature (sand-filled columns) root phenotyping platforms. The RSA model RootBox was parameterized with seedling traits to simulate the fully developed root systems. Measured and modelled root length, first-order lateral number, and root distribution were compared to determine key traits for model-based prediction. No direct relationship in root traits (tap, lateral length, interbranch distance) was evident between phenotyping systems. RootBox significantly improved the inference over phenotyping platforms. Seedling plant tap and lateral root elongation rates and interbranch distance were sufficient model parameters to predict genotype ranking in total root length with an RSpearman of 0.83. Parameterization including uneven lateral spacing via a scaling function substantially improved the prediction of architectures underlying the differently sized root systems. We conclude that RSA models can solve the inference problem of seedling root phenotyping. RSA models should be included in the phenotyping pipeline to provide reliable information on mature root systems to breeding research. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Early growth stages salinity stress tolerance in CM72 x Gairdner doubled haploid barley population

PubMed Central

Angessa, Tefera Tolera; Zhang, Xiao-Qi; Zhou, Gaofeng; Broughton, Sue; Zhang, Wenying

2017-01-01

A doubled haploid (DH) population of barley (Hordeum vulgare L.) generated from salinity tolerant genotype CM72 and salinity sensitive variety Gairdner was studied for salinity stress tolerance at germination, seedling emergence and first leaf full expansion growth stages. Germination study was conducted with deionized water, 150 mM and 300 mM NaCl treatments. Seedling stage salinity tolerance was conducted with three treatments: control, 150 mM NaCl added at seedling emergence and first leaf full expansion growth stages. Results from this study revealed transgressive phenotypic segregations for germination percentage and biomass at seedling stage. Twelve QTL were identified on chromosomes 2H–6H each explaining 10–25% of the phenotypic variations. A QTL located at 176.5 cM on chromosome 3H was linked with fresh weight per plant and dry weight per plant in salinity stress induced at first leaf full expansion growth stage, and dry weight per plant in salinity stress induced at seedling emergence. A stable QTL for germination at both 150 and 300 mM salinity stress was mapped on chromosome 2H but distantly located from a QTL linked with seedling stage salinity stress tolerance. QTL, associated markers and genotypes identified in this study play important roles in developing salinity stress tolerant barley varieties. PMID:28640858

N-Acylethanolamine Metabolism Interacts with Abscisic Acid Signaling in Arabidopsis thaliana Seedlings[W][OA

PubMed Central

Teaster, Neal D.; Motes, Christy M.; Tang, Yuhong; Wiant, William C.; Cotter, Matthew Q.; Wang, Yuh-Shuh; Kilaru, Aruna; Venables, Barney J.; Hasenstein, Karl H.; Gonzalez, Gabriel; Blancaflor, Elison B.; Chapman, Kent D.

2007-01-01

N-Acylethanolamines (NAEs) are bioactive acylamides that are present in a wide range of organisms. In plants, NAEs are generally elevated in desiccated seeds, suggesting that they may play a role in seed physiology. NAE and abscisic acid (ABA) levels were depleted during seed germination, and both metabolites inhibited the growth of Arabidopsis thaliana seedlings within a similar developmental window. Combined application of low levels of ABA and NAE produced a more dramatic reduction in germination and growth than either compound alone. Transcript profiling and gene expression studies in NAE-treated seedlings revealed elevated transcripts for a number of ABA-responsive genes and genes typically enriched in desiccated seeds. The levels of ABI3 transcripts were inversely associated with NAE-modulated growth. Overexpression of the Arabidopsis NAE degrading enzyme fatty acid amide hydrolase resulted in seedlings that were hypersensitive to ABA, whereas the ABA-insensitive mutants, abi1-1, abi2-1, and abi3-1, exhibited reduced sensitivity to NAE. Collectively, our data indicate that an intact ABA signaling pathway is required for NAE action and that NAE may intersect the ABA pathway downstream from ABA. We propose that NAE metabolism interacts with ABA in the negative regulation of seedling development and that normal seedling establishment depends on the reduction of the endogenous levels of both metabolites. PMID:17766402

Woody plant establishment in grassed reclamation areas of the Athabasca oil sands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fedkenheuer, A.W.

1980-12-01

The primary end land use for areas disturbed by the Syncrude Canada Ltd. oil sands surface mining venture is forest cover. Short term erosion control is of concern, however, and this results in the early establishment of a grass and legume cover. Problems have subsequently been encountered in attempts to establish woody plants in the grass and legume cover. Vegetation competition for soil moisture and nutrients and rodent damage to woody seedlings have been the major problem areas. A study was initiated in 1978 to evaluate methods of manipulating the grass and legume cover sufficiently to improve success rates inmore » establishing a variety of shrubs and trees. Five replicated treatments using the chemical herbicide glyphosate, soil scarification and fire alone plus soil scarification were established on an area seeded to grass and legumes in spring 1976. Woody plant survival and rodent damage, populations and distribution are being assessed annually in spring and fall. Rodent damage to woody seedlings was heavy in fall 1978 with 80 percent of the deciduous seedlings on non-scarified plots being damaged. In June 1979, 98 percent of the deciduous plants on the control and herbicide treatment areas were damaged. Damage to conifers was approximately 30 percent less during this time. Prescribed burning and mechanical scarification substantially reduced rodent damage. Seedling survival was variable with Amelanchier alnifolia, Pinus contorta and Populus tremuloides consistently exhibiting the highest survival rates.« less

Effects of untreated and treated wastewater at the morphological, physiological and biochemical levels on seed germination and development of sorghum (Sorghum bicolor (L.) Moench), alfalfa (Medicago sativa L.) and fescue (Festuca arundinacea Schreb.).

PubMed

Rekik, Imen; Chaabane, Zayneb; Missaoui, Amara; Bouket, Ali Chenari; Luptakova, Lenka; Elleuch, Amine; Belbahri, Lassaad

2017-03-15

Wastewater reuse in agriculture may help mitigate water scarcity. This may be reached if high quality treatments removing harmful pollutants are applied. The aim of the present study was to compare the effect of untreated (UTW) and treated wastewater (TW) on germination and seedlings development of alfalfa (Medicago sativa L.), fescue (Festuca arundinacea Schreb.) and sorghum (Sorghum bicolor (L.) Moench). UTW presented high turbidity (130 NTU), chemical and biological oxygen demand (COD, 719mgL -1 , BOD 5, 291mgL -1 ) and metal concentrations. These levels caused mortality (18% for fescue), decreased germination speed in seeds (37.5% for alfalfa) and reductions of root and stem length in seedlings (80% and 22% respectively for alfalfa). Adverse effects on seeds germination were reflected at the biochemical level by increased H 2 O 2 levels (6 times for sorghum after 5days) and by increased Malondialdehyde (MDA) levels (more than 600 times for sorghum roots) during seedlings development. When TW was used, these parameters were close to control seeds ones. They were also dependent on plant species and developmental stage. Therefore, for efficient reclaimed wastewater reuse in irrigation, suitable crops, displaying wide tolerance to toxic contents during germination and later seedling development stages have to be selected. Copyright © 2016 Elsevier B.V. All rights reserved.

Gravitropism of hypocotyls of wild-type and starch-deficient Arabidopsis seedlings in spaceflight studies

NASA Technical Reports Server (NTRS)

Kiss, J. Z.; Edelmann, R. E.; Wood, P. C.

1999-01-01

The major purpose of this spaceflight project was to investigate the starch-statolith hypothesis for gravity perception, and a secondary goal was to study plant growth and development under spaceflight conditions. This research was based on our ground studies of gravity perception in the wild type and three starch-deficient (one starchless and two reduced starch) mutants of Arabidopsis thaliana (L.) Heynh. Dark-grown seedlings that developed in microgravity were given one of several (30 min, 60 min, or 90 min) 1-g stimuli by an on-board centrifuge, and additional controls for seedling development also were performed. These latter control experiments included a morphological study of plants that developed in space in microgravity (F microg), in space on a centrifuge (F 1g), on the ground (G 1g), and on a rotating clinostat on the ground. Since elevated levels of ethylene were reported in the spacecraft atmosphere, additional controls for morphology and gravitropism with added ethylene also were performed. While exogenous ethylene reduced the absolute magnitude of the response in all four strains of Arabidopsis, this gas did not appear to change the relative graviresponsiveness among the strains. The relative response of hypocotyls of microgravity-grown seedlings to the stimuli provided by the in-flight centrifuge was: wild type > starch-deficient mutants. Although the protoplast pressure model for gravity perception cannot be excluded, these results are consistent with a statolith-based model for perception in plants.

Sediment burial stimulates the growth and propagule production of Spartina alterniflora Loisel.

NASA Astrophysics Data System (ADS)

Deng, Zifa; An, Shuqing; Zhao, Congjiao; Chen, Lin; Zhou, Changfang; Zhi, Yingbiao; Li, Hongli

2008-03-01

Spartina alterniflora Loisel., an extensively invasive species on the Chinese coast, is a focus of increasing management concern due to its high expansion rate in estuaries and tidal zone, and the significant damage it causes to native ecosystems. In order to understand the processes and mechanisms of invasion of S. alterniflora in China, the impact of three sediment types (sand, sand-loam mixture and loam) and five buried patterns (unburied, 50% burial of initial plant height, 75% burial of initial plant height, complete burial and repeated burial) on the growth of seedlings or ramets was investigated. Results showed that each of the three factors (sediment types, burial pattern and plant materials) and interactions between/among them, significantly affected height and clonal growth, and biomass accumulation and allocation. Plant height, total biomass and number of new vegetative propagules significantly increased with progressive burial treatments. However, the complete burial treatment resulted in the death of all plant materials, and the maximum values of three parameters were found in the 50% burial or repeated burial treatments. Plant responses were determined by the instantaneous thickness of sediment of each time burial rather than by the total quantity of repeated burial. The growth of S. alterniflora was not shown to be dependent on specific types of sediment in sedimentation environment. In contrast to the unburied control, the proportion of primary tillers produced directly from initial individuals and the ratio between the aboveground and belowground biomass were greater under burial treatments. Seedlings produced more new vegetative propagules than vegetative offspring in all experimental treatments, and the former were apt to produce ramets from rhizomes rather than primary tillers. It is concluded that under various sedimentation environments, the clonal spread efficiency of seedlings was higher than that of vegetative offspring, and there is a positive feedback relationship between sedimentation and the growth of S. alterniflora. Thus, moderate sedimentation may stimulate the invasion of exotic species, S. alterniflora in coastal China.

Hormone-Mediated Pattern Formation in Seedling of Plants: a Competitive Growth Dynamics Model

NASA Astrophysics Data System (ADS)

Kawaguchi, Satoshi; Mimura, Masayasu; Ohya, Tomoyuki; Oikawa, Noriko; Okabe, Hirotaka; Kai, Shoichi

2001-10-01

An ecologically relevant pattern formation process mediated by hormonal interactions among growing seedlings is modeled based on the experimental observations on the effects of indole acetic acid, which can act as an inhibitor and activator of root growth depending on its concentration. In the absence of any lateral root with constant hormone-sensitivity, the edge effect phenomenon is obtained depending on the secretion rate of hormone from the main root. Introduction of growth-stage-dependent hormone-sensitivity drastically amplifies the initial randomness, resulting in spatially irregular macroscopic patterns. When the lateral root growth is introduced, periodic patterns are obtained whose periodicity depends on the length of lateral roots. The growth-stage-dependent hormone-sensitivity and the lateral root growth are crucial for macroscopic periodic-pattern formation.

Proteome Analysis of Peroxisomes from Etiolated Arabidopsis Seedlings Identifies a Peroxisomal Protease Involved in β-Oxidation and Development1[C][W][OPEN

PubMed Central

Quan, Sheng; Yang, Pingfang; Cassin-Ross, Gaëlle; Kaur, Navneet; Switzenberg, Robert; Aung, Kyaw; Li, Jiying; Hu, Jianping

2013-01-01

Plant peroxisomes are highly dynamic organelles that mediate a suite of metabolic processes crucial to development. Peroxisomes in seeds/dark-grown seedlings and in photosynthetic tissues constitute two major subtypes of plant peroxisomes, which had been postulated to contain distinct primary biochemical properties. Multiple in-depth proteomic analyses had been performed on leaf peroxisomes, yet the major makeup of peroxisomes in seeds or dark-grown seedlings remained unclear. To compare the metabolic pathways of the two dominant plant peroxisomal subtypes and discover new peroxisomal proteins that function specifically during seed germination, we performed proteomic analysis of peroxisomes from etiolated Arabidopsis (Arabidopsis thaliana) seedlings. The detection of 77 peroxisomal proteins allowed us to perform comparative analysis with the peroxisomal proteome of green leaves, which revealed a large overlap between these two primary peroxisomal variants. Subcellular targeting analysis by fluorescence microscopy validated around 10 new peroxisomal proteins in Arabidopsis. Mutant analysis suggested the role of the cysteine protease RESPONSE TO DROUGHT21A-LIKE1 in β-oxidation, seed germination, and growth. This work provides a much-needed road map of a major type of plant peroxisome and has established a basis for future investigations of peroxisomal proteolytic processes to understand their roles in development and in plant interaction with the environment. PMID:24130194

Further Characterization of Genetically Distinct Groups of Acidovorax citrulli Strains.

PubMed

Zivanovic, M; Walcott, R R

2017-01-01

Bacterial fruit blotch of cucurbits (BFB) is caused by the gram-negative bacterium Acidovorax citrulli, whose populations can be distinguished into two genetically distinct groups, I and II. Based on visual assessment of BFB severity on cucurbit seedlings and fruit after inoculation under greenhouse conditions, group I A. citrulli strains have been reported to be moderately to highly virulent on several cucurbit hosts, whereas group II strains have exhibited high virulence on watermelon but low virulence on other cucurbits. Additionally, group I strains are recovered from a range of cucurbit hosts, while group II strains are predominantly found on watermelon. The goal of this research was to develop tools to characterize and rapidly distinguish group I and II A. citrulli strains. We first sought to determine whether quantification of A. citrulli colonization of cucurbit seedling tissue reflects the differences between group I and II strains established by visual assessment of BFB symptom severity. Spray inoculation of melon seedlings with cell suspensions containing approximately 1 × 10 4 CFU/ml resulted in significantly higher (P = 0.01) population growth of M6 (group I; mean area under population growth curve [AUPGC] = 43.73) than that of AAC00-1 (group II; mean AUPGC = 39.33) by 10 days after inoculation. We also investigated the natural spread of bacterial cells and the resulting BFB incidence on watermelon and melon seedlings exposed to three group I and three group II A. citrulli strains under mist chamber conditions. After 5 days of exposure, the mean BFB incidence on melon seedlings exposed to representative group II A. citrulli strains was significantly lower (25 and 3.98% in experiments 1 and 2, respectively) than on melon seedlings exposed to representative group I strains (94.44 and 76.11% in experiments 1 and 2, respectively), and on watermelon seedlings exposed to representative group I and II strains (70 to 93.33%). Finally, we developed a polymerase chain reaction assay based on the putative type III secretion effector gene, Aave_2166, to rapidly distinguish group I and II A. citrulli strains. This assay will be important for future epidemiological studies on BFB.

Distinct genecological patterns in seedlings of Norway spruce and silver fir from a mountainous landscape.

PubMed

Frank, Aline; Sperisen, Christoph; Howe, Glenn Thomas; Brang, Peter; Walthert, Lorenz; St Clair, John Bradley; Heiri, Caroline

2017-01-01

Understanding the genecology of forest trees is critical for gene conservation, for predicting the effects of climate change and climate change adaptation, and for successful reforestation. Although common genecological patterns have emerged, species-specific details are also important. Which species are most vulnerable to climate change? Which are the most important adaptive traits and environmental drivers of natural selection? Even though species have been classified as adaptive specialists vs. adaptive generalists, large-scale studies comparing different species in the same experiment are rare. We studied the genecology of Norway spruce (Picea abies) and silver fir (Abies alba), two co-occurring but ecologically distinct European conifers in Central Europe. For each species, we collected seed from more than 90 populations across Switzerland, established a seedling common-garden test, and developed genecological models that associate population variation in seedling growth and phenology to climate, soil properties, and site water balance. Population differentiation and associations between seedling traits and environmental variables were much stronger for Norway spruce than for silver fir, and stronger for seedling height growth than for bud phenology. In Norway spruce, height growth and second flushing were strongly associated with temperature and elevation, with seedlings from the lowlands being taller and more prone to second flush than seedlings from the Alps. In silver fir, height growth was more weakly associated with temperature and elevation, but also associated with water availability. Soil characteristics explained little population variation in both species. We conclude that Norway spruce has become an adaptive specialist because trade-offs between rapid juvenile growth and frost avoidance have subjected it to strong diversifying natural selection based on temperature. In contrast, because silver fir has a more conservative growth habit, it has evolved to become an adaptive generalist. This study demonstrates that co-occurring tree species can develop very different adaptive strategies under identical environmental conditions, and suggests that Norway spruce might be more vulnerable to future maladaptation due to rapid climate change than silver fir. © 2016 by the Ecological Society of America.

Isolation, characterization, and formulation of antagonistic bacteria for the management of seedlings damping-off and root rot disease of cucumber.

PubMed

Khabbaz, Salah Eddin; Abbasi, Pervaiz A

2014-01-01

Antagonistic bacteria are common soil inhabitants with potential to be developed into biofungicides for the management of seedling damping-off, root rot, and other soil-borne diseases of various crops. In this study, antagonistic bacteria were isolated from a commercial potato field and screened for their growth inhibition of fungal and oomycete pathogens in laboratory tests. The biocontrol potential of the 3 most effective antagonistic bacteria from the in vitro tests was evaluated against seedling damping-off and root rot of cucumber caused by Pythium ultimum. Based on phenotypic characteristics, biochemical tests, and sequence analysis of 16S-23S rDNA gene, the 3 antagonistic bacteria were identified as Pseudomonas fluorescens (isolate 9A-14), Pseudomonas sp. (isolate 8D-45), and Bacillus subtilis (isolate 8B-1). All 3 bacteria promoted plant growth and suppressed Pythium damping-off and root rot of cucumber seedlings in growth-room assays. Both pre- and post-planting application of these bacteria to an infested peat mix significantly increased plant fresh masses by 113%-184% and percentage of healthy seedlings by 100%-290%, and decreased damping-off and root rot severity by 27%-50%. The peat and talc formulations of these antagonistic bacteria applied as seed or amendment treatments to the infested peat mix effectively controlled Pythium damping-off and root rot of cucumber seedlings and enhanced plant growth. The survival of all 3 antagonistic bacteria in peat and talc formulations decreased over time at room temperature, but the populations remained above 10(8) CFU/g during the 180-day storage period. The peat formulation of a mixture of 3 bacteria was the best seed treatment, significantly increasing the plant fresh masses by 245% as compared with the Pythium control, and by 61.4% as compared with the noninfested control. This study suggests that the indigenous bacteria from agricultural soils can be developed and formulated as biofungicides for minimizing the early crop losses caused by seedling damping-off and root rot diseases.

Ectomycorrhizal fungi reduce the light compensation point and promote carbon fixation of Pinus thunbergii seedlings to adapt to shade environments.

PubMed

Shi, Liang; Wang, Jie; Liu, Binhao; Nara, Kazuhide; Lian, Chunlan; Shen, Zhenguo; Xia, Yan; Chen, Yahua

2017-11-01

We examined the effects of three ectomycorrhizal (ECM) symbionts on the growth and photosynthesis capacity of Japanese black pine (Pinus thunbergii) seedlings and estimated physiological and photosynthetic parameters such as the light compensation point (LCP), biomass, and phosphorus (Pi) concentration of P. thunbergii seedlings. Through this investigation, we documented a new role of ectomycorrhizal (ECM) fungi: enhancement of the survival and competitiveness of P. thunbergii seedlings under low-light condition by reducing the LCP of seedlings. At a CO 2 concentration of 400 ppm, the LCP of seedlings with ECM inoculations was 40-70 μmol photons m -2  s -1 , significantly lower than that of non-mycorrhizal (NM) seedlings (200 μmol photons m -2  s -1 ). In addition, photosynthetic carbon fixation (Pn) increased with light intensity and CO 2 level, and the Pn of ECM seedlings was significantly higher than that of NM seedlings; Pisolithus sp. (Pt)- and Laccaria amethystea (La)-mycorrhizal seedlings had significantly lower Pn than Cenococcum geophilum (Cg)-mycorrhizal seedlings. However, La-mycorrhizal seedlings exhibited the highest fresh weight, relative water content (RWC), and the lowest LCP in the mycorrhizal group. Concomitantly, ECM seedlings showed significantly increased chlorophyll content of needles and higher Pi concentrations compared to NM seedlings. Overall, ECM symbionts promoted growth and photosynthesis while reducing the LCP of P. thunbergii seedlings. These findings indicate that ECM fungi can enhance the survival and competitiveness of host seedlings under low light.

Early stand development in a red oak-paper birch stand regenerated through the shelterwood system in northern Wisconsin

Treesearch

Terry F. Strong

2005-01-01

A study was established 20 years ago in northern Wisconsin to examine the minimum size of seedlings to ensure seedling survival after the overstory was removed in a red oak (Quercus rubra L.) and paper birch (Betula papyrifera Marsh.) stand. About 65 percent of the site was scarified in 1985 with a woods disc. The overstory was...

Approach and rationale to developing an IPM program: Examples of insect management in British Columbia reforestation nurseries

Treesearch

David Trotter

2002-01-01

Insects, weeds, and diseases are a significant part of the production process that nursery growers must consider in order to effectively grow the desired conifer seedling. For the pests and seedlings, the underlying theme is survival, which encompasses 3 major components: stimulus, recognition, and response (Shigo 1991). Thus, the continuation of any system depends on...

Ectomycorrhizal fungal communities on seedlings and conspecific trees of Pinus mugo grown on the coastal dunes of the Curonian Spit in Lithuania.

PubMed

Aučina, Algis; Rudawska, Maria; Leski, Tomasz; Ryliškis, Darius; Pietras, Marcin; Riepšas, Edvardas

2011-04-01

Ectomycorrhizal (ECM) communities of mature trees and regenerating seedlings of a non-native tree species Pinus mugo grown in a harsh environment of the coastal region of the Curonian Spit National Park in Lithuania were assessed. We established three study sites (S1, S2, and S3) that were separated from each other by 15 km. The ECM species richness was rather low in particular for mature, 100-year-old trees: 12 ectomycorrhizal taxa were identified by molecular analysis from 11 distinguished morphotypes. All 12 taxa were present on seedlings and on mature trees, with between 8-11 and 9-11 taxa present on seedlings and mature trees, respectively. Cenococcum geophilum dominated all ECM communities, but the relative abundance of C. geophilum mycorrhizas was nearly two times higher on seedlings than on mature trees. Mycorrhizal associations formed by Wilcoxina sp., Lactarius rufus, and Russula paludosa were also abundant. Several fungal taxa were only occasionally detected, including Cortinarius sp., Cortinarius obtusus, Cortinarius croceus, and Meliniomyces sp. Shannon's diversity indices for the ECM assemblages of P. mugo ranged from 0.98 to 1.09 for seedling and from 1.05 to 1.31 for mature trees. According to analysis of similarity, the mycorrhizal communities were similar between the sites (R = 0.085; P = 0.06) and only slightly separated between seedlings and mature trees (R = 0.24; P < 0.0001). An incidental fruiting body survey that was conducted weakly reflected the below-ground assessment of the ECM fungal community and once again showed that ECM and fruiting body studies commonly supply different partial accounts of the true ECM fungal diversity. Our results show that P. mugo has moved into quite distinct habitats and is able to adapt a suite of ECM symbionts that sufficiently support growth and development of this tree and allow for natural seedling regeneration.

Leafspot of Black Cherry (Pest Alert)

Treesearch

USDA Forest Service

1992-01-01

A leafspot caused by the fungus Blumeriella jaapii can damage black cherry seedlings in both forests and nurseries. The disease was formerly know as Coccomyces leafspot (from the genus of synonyms for the causal fungus). Affected leaves bear spots that initially are purple. In moist conditions, light-colored spore masses may ooze from fruiting bodies in these spots on...

Field performance of Nuttall Oak on former agricultural fields: Initial effects of nursery source and competition control

Treesearch

Emile S. Gardiner; K. Francis Salifu; Douglass F. Jacobs; George Hernandez; Ronald P. Overton

2007-01-01

Nuttall oak (Quercus nuttallii Palm.) seedlings raised at state nurseries in Mississippi, Louisiana, and Arkansas were morphologically different in height, root collar diameter, fresh mass, number of first-order lateral roots, root volume, and height-to-root collar diameter ratio. When outplanted on afforestation sites in the Lower Mississippi...

INTERACTIVE EFFECTS OF CO2 AND O3 ON A PONDEROSA PINE PLANT/LITTER/SOIL MESOCOSM

EPA Science Inventory

To study individual and combined impacts of two important atmospheric trace gases, CO2 and O3, on C and N cycling in forest ecosystems; a four-year experiment using a small-scale ponderosa pine (Pinus ponderosa Laws.) seedling/soil/litter system was initiated in April, 1998. Th...

Field performance of Nuttall oak on former agricultural fields: Initial effects of nursery source and competition control

Treesearch

Emile S. Gardiner; K. Francis Salifu; Douglass F. Jacobs; George Hernandez; Ronald P. Overton

2007-01-01

Nuttall oak (Quercus nuttallii Palm.) seedlings raised at state nurseries in Mississippi, Louisiana, and Arkansas were morphologically different in height, root collar diameter, fresh mass, number of first-order lateral roots, root volume, and height-to-root collar diameter ratio. When outplanted on afforestation sites in the Lower Mississippi...

Importance of Seedyear, Seedbed, and Overstory for Establishment of Natural Loblolly and Shortleaf Pine Regenerationin Southern Arkansas

Treesearch

Michael D. Cain

1991-01-01

First-year density and quadrat stocking of naturally established loblolly and shortleaf pine regeneration were monitored forfive consecutive seedyearson disturbed and undisturbed seedbeds. Compared to untreatedchecks,additional gainsin pine seedling density as a result of exposing mineral soil were not as great as initial gains achieved by control of overtopping...

Ensuring that forests are adapted to future climates

Treesearch

Brad St. Clair; Glenn Howe

2010-01-01

Successful reforestation requires that planted or naturally regenerated seedlings are well suited to a site. Genetic studies of forest trees provide ample evidence of large differences among seed sources in adaptive traits--traits such as the timing of growth initiation and cessation, cold and drought hardiness, and growth rates. Much of this variation is related to...

Overhead shading and growth of young longleaf pine

Treesearch

John C. Gilbert; John S. Kush; Ralph S. Meldahl; William D. Boyer; Dean H. Gjerstad

2014-01-01

A study to determine the effects of environmental conditions on the growth of longleaf pine (Pinus palustris Mill.) was initiated in 1969 on the Escambia Experimental Forest near Brewton, Alabama, USA. This study sample consisted of forty young naturally regenerated, even aged longleaf pine seedlings evenly divided between two soil types. At the beginning of the study...

Big sagebrush (Artemisia tridentata) in a shifting climate context: Assessment of seedling responses to climate

Treesearch

Martha A. Brabec

2014-01-01

The loss of big sagebrush (Artemisia tridentata) throughout the Great Basin Desert has motivated efforts to restore it because of fire and other disturbance effects on sagebrush-dependent wildlife and ecosystem function. Initial establishment is the first challenge to restoration, and appropriateness of seeds, climate, and weather variability are factors that may...

Factors Limiting the Establishment of a Chaparral Oak, Quercus durata Jeps., in Grassland

Treesearch

Kimberlyn Williams; Stephen D. Davis; Barbara L. Gartner; Staffan Karlsson

1991-01-01

We studied factors that restrict colonization of grassland by Quercus durata Jeps., an oak commonly found in chaparral on serpentine soils. The study site contained a chaparral/ grassland border that had been stable for at least 50 years. Monitoring of acorns planted in the chaparral understory and grassland revealed that, although initial seedling...

Promoting Effects of a Single Rhodopseudomonas palustris Inoculant on Plant Growth by Brassica rapa chinensis under Low Fertilizer Input

PubMed Central

Wong, Wai-Tak; Tseng, Ching-Han; Hsu, Shu-Hua; Lur, Huu-Sheng; Mo, Chia-Wei; Huang, Chu-Ning; Hsu, Shu-Chiung; Lee, Kung-Ta; Liu, Chi-Te

2014-01-01

Several Rhodopseudomonas palustris strains have been isolated from rice paddy fields in Taiwan by combining the Winogradsky column method and molecular marker detection. These isolates were initially screened by employing seed germination and seedling vigor assays to evaluate their potential as inoculants. To fulfill the demand in the present farming system for reducing the application of chemical fertilizers, we assessed the plant growth-promoting effects of the R. palustris YSC3, YSC4, and PS3 inoculants on Brassica rapa chinensis (Chinese cabbage) cultivated under a half quantity of fertilizer. The results obtained showed that supplementation with approximately 4.0×106 CFU g−1 soil of the PS3 inoculant at half the amount of fertilizer consistently produced the same plant growth potential as 100% fertility, and also increased the nitrogen use efficiency of the applied fertilizer nutrients. Furthermore, we noted that the plant growth-promotion rate elicited by PS3 was markedly higher with old seeds than with new seeds, suggesting it has the potential to boost the development of seedlings that were germinated from carry-over seeds of poor quality. These beneficial traits suggest that the PS3 isolate may serve as a potential PGPR inoculant for integrated nutrient management in agriculture. PMID:25130882

Role of thioproline on seed germination: interaction ROS-ABA and effects on antioxidative metabolism.

PubMed

Barba-Espin, Gregorio; Nicolas, Eduardo; Almansa, Maria Soledad; Cantero-Navarro, Elena; Albacete, Alfonso; Hernández, José Antonio; Díaz-Vivancos, Pedro

2012-10-01

In this work we investigate the effect of the imbibition of pea seeds with different thioproline (TP) concentrations on the germination percentage and the early growth of the seedlings. The interaction between TP and hydrogen peroxide (H₂O₂) treatments is also analysed in order to test if any synergy in germination and growth occurs. Although the imbibition of pea seeds in the presence of TP did not significantly improve the germination percentage, TP and/or H₂O₂ pre-treatments increased seedlings growth. This increase in seedling growth was reduced by abscisic acid (ABA) addition. Imbibition of pea seeds in the presence of ABA also reduced the endogenous H₂O₂ contents of pea seedlings in control and TP-treated seeds. The incubation of pea seeds with TP and/or H₂O₂ in presence or absence of ABA decreased the activity of H₂O₂-scavenging enzymes. The increase of the endogenous H₂O₂ contents observed in TP and/or H₂O₂ treatments in absence of ABA could be correlated with the decrease in these activities. Finally, the hormone profile of pea seedlings was investigated. The results show that the increase in seedling growth is correlated with a decrease in ABA in samples pre-treated with H₂O₂ and TP + H₂O₂. Nevertheless, no significant differences in endogenous ABA concentration were observed with the TP pre-treatment. This paper suggests a relationship between endogenous H₂O₂ contents and plant growth, so reinforcing the intricate crosstalk between reactive oxygen species (ROS) and plant hormones in seed germination signalling and early seedling development. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Hydrogen sulfide acts as a downstream signal molecule in salicylic acid-induced heat tolerance in maize (Zea mays L.) seedlings.

PubMed

Li, Zhong-Guang; Xie, Lin-Run; Li, Xiao-Juan

2015-04-01

Salicylic acid (SA), 2-hydroxy benzoic acid, is a small phenolic compound with multifunction that is involved in plant growth, development, and the acquisition of stress tolerance. In recent years, hydrogen sulfide (H2S) has been found to have similar functions, but cross talk between SA and H2S in the acquisition of heat tolerance is not clear. In this study, pretreatment of maize seedlings with SA improved the survival percentage of seedlings under heat stress, indicating that SA pretreatment could improve the heat tolerance of maize seedlings. In addition, treatment with SA enhanced the activity of L-cysteine desulfhydrase (L-DES), a key enzyme in H2S biosynthesis, which in turn induced accumulation of endogenous H2S. Interestingly, SA-induced heat tolerance was enhanced by addition of NaHS, a H2S donor, but weakened by specific inhibitors of H2S biosynthesis DL-propargylglycine (PAG) and its scavenger hydroxylamine (HT). Furthermore, pretreatment with paclobutrazol (PAC) and 2-aminoindan-2-phosphonic acid (AIP), inhibitors of SA biosynthesis, had no significant effect on NaHS-induced heat tolerance of maize seedlings. Similarly, significant change in the activities of phenylalanine ammonia lyase (PAL) and benzoic-acid-2-hydroxylase (BA2H), the key enzymes in SA biosynthesis, and the content of endogenous SA, was not observed in maize seedlings by NaHS treatment. All of the above-mentioned results suggest that SA pretreatment could improve the heat tolerance of maize seedlings, and H2S might be a novel downstream signal molecule in SA-induced heat tolerance. Copyright © 2015 Elsevier GmbH. All rights reserved.

Seedling growth and biomass allocation in relation to leaf habit and shade tolerance among 10 temperate tree species.

PubMed

Modrzyński, Jerzy; Chmura, Daniel J; Tjoelker, Mark G

2015-08-01

Initial growth of germinated seeds is an important life history stage, critical for establishment and succession in forests. Important questions remain regarding the differences among species in early growth potential arising from shade tolerance. In addition, the role of leaf habit in shaping relationships underlying shade tolerance-related differences in seedling growth remains unresolved. In this study we examined variation in morphological and physiological traits among seedlings of 10 forest tree species of the European temperate zone varying in shade tolerance and leaf habit (broadleaved winter-deciduous species vs needle-leaved conifers) during a 10-week period. Seeds were germinated and grown in a controlled environment simulating an intermediate forest understory light environment to resolve species differences in initial growth and biomass allocation. In the high-resource experimental conditions during the study, seedlings increased biomass allocation to roots at the cost of leaf biomass independent of shade tolerance and leaf habit. Strong correlations between relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), specific leaf area (SLA) and leaf mass fraction (LMF) indicate that physiology and biomass allocation were equally important determinants of RGR as plant structure and leaf morphology among these species. Our findings highlight the importance of seed mass- and seed size-related root morphology (specific root length-SRL) for shade tolerance during early ontogeny. Leaf and plant morphology (SLA, LAR) were more successful in explaining variation among species due to leaf habit than shade tolerance. In both broadleaves and conifers, shade-tolerant species had lower SRL and greater allocation of biomass to stems (stem mass fraction). Light-seeded shade-intolerant species with greater SRL had greater RGR in both leaf habit groups. However, the greatest plant mass was accumulated in the group of heavy-seeded shade-tolerant broadleaves. The results of our study suggest that the combinations of plant attributes enhancing growth under high light vary with shade tolerance, but differ between leaf habit groups. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Dynamical behavior of psb gene transcripts in greening wheat seedlings. I. Time course of accumulation of the pshA through psbN gene transcripts during light-induced greening.

PubMed

Kawaguchi, H; Fukuda, I; Shiina, T; Toyoshima, Y

1992-11-01

The time course of the accumulation of the transcripts from 13 psb genes encoding a major part of the proteins composing photosystem II during light-induced greening of dark-grown wheat seedlings was examined focusing on early stages of plastid development (0.5 h through 72 h). The 13 genes can be divided into three groups. (1) The psbA gene is transcribed as a single transcript of 1.3 kb in the dark-grown seedlings, but its level increases 5- to 7-fold in response to light due to selective increase in RNA stability as well as in transcription activity. (2) The psbE-F-L-J operon, psbM and psbN genes are transcribed as a single transcript of 1.1 kb, two transcripts of 0.5 and 0.7 kb and a single transcript of 0.3 kb, respectively, in the dark-grown seedlings. The levels of accumulation of every transcript remain unchanged or rather decrease during plastid development under illumination. (3) The psbK-I-D-C gene cluster and psbB-H operon exhibit fairly complicated northern hybridization patterns during the greening process. When a psbC or psbD gene probe was used for northern hybridization, five transcripts differing in length were detected in the etioplasts from 5-day old dark-grown seedlings. After 2 h illumination, two new transcripts of different length appeared. Light induction of new transcripts was also observed in the psbB-H operon.

Effect of carbon nanomaterials on the germination and growth of rice plants.

PubMed

Nair, Remya; Mohamed, M Sheikh; Gao, Wei; Maekawa, Toru; Yoshida, Yasuhiko; Ajayan, Pulickel M; Kumar, D Sakthi

2012-03-01

For the successful diverse applications of different nanomaterials in life sciences, it is necessary to understand the ultimate fate, distribution and potential environmental impacts of manufactured nanomaterials. Phytotoxicity studies using higher plants is an important criterion for understanding the toxicity of engineered nanomaterials. We studied the effects of engineered carbon nanomaterials of various dimensionalities (carbon nanotubes, C60, graphene) on the germination of rice seeds. A pronounced increase in the rate of germination was observed for rice seeds in the presence of some of these carbon nanostructures, in particular the nanotubes. Increased water content was observed in the carbon nanomaterial treated seeds during germination compared to controls. The germinated seeds were then grown in a basal growth medium supplemented with carbon nanomaterials for studying their impact on further seedling growth. Treated seedlings appeared to be healthier with well-developed root and shoot systems compared to control seedlings. Our results indicate the possible use for carbon nanomaterials as enhancers in the growth of rice seedlings.

Role of GA3, GA4 and uniconazole-P in controlling gravitropism and tension wood formation in Fraxinus mandshurica Rupr. var. japonica Maxim. seedlings.

PubMed

Jiang, Sha; Xu, Ke; Wang, Yong-Zhou; Ren, Yan-Ping; Gu, Song

2008-01-01

GA(3) and GA(4) (gibberellins) play an important role in controlling gravitropism and tension wood formation in woody angiosperms. In order to improve our understanding of the role of GA(3) and GA(4) on xylem cell formation and the G-layer, we studied the effect of GA(3) and GA(4) and uniconazole-P, which is an inhibitor of GA biosynthesis, on tension wood formation by gravity in Fraxinus mandshurica Rupr. var. japonica Maxim. seedlings. Forty seedlings were divided into two groups; one group was placed upright and the other tilted. Each group was further divided into four sub-groups subjected to the following treatments: 3.43 x 10(-9) micromol acetone as control, 5.78 x 10(-8) micromol gibberellic acid (GA(3)), 6.21 x 10(-8) micromol GA(4), and 6.86 x 10(-8) micromol uniconazole-P. During the experimental period, GAs-treated seedlings exhibited negative gravitropism, whereas application of uniconazole-P inhibited negative gravitropic stem bending. GA(3) and GA(4) promoted wood fibers that possessed a gelatinous layer on the upper side, whereas uniconazole-P inhibited wood formation but did not inhibit the differentiation of the gelatinous layer in wood fibers on the upper side. These results suggest that: (i) both the formation of gelatinous fibers and the quantity of xylem production are important for the negative gravitropism in horizontally-positioned seedlings; (ii) GA(3) and GA(4) affect wood production more than differentiation of the gelatinous layer in wood fibers; G-layer development may be regulated by other hormones via the indirect-role of GA(3) and GA(4) in horizontally-positioned F. mandshurica seedlings rather than the direct effect of GAs; and (iii) the mechanism for upward wood stem bending is different to the newly developed shoot bending in reaction to gravity in this species.

Interactions of Seedborne Bacterial Pathogens with Host and Non-Host Plants in Relation to Seed Infestation and Seedling Transmission

PubMed Central

Dutta, Bhabesh; Gitaitis, Ronald; Smith, Samuel; Langston, David

2014-01-01

The ability of seed-borne bacterial pathogens (Acidovorax citrulli, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato, Xanthomonas euvesicatoria, and Pseudomonas syringae pv. glycinea) to infest seeds of host and non-host plants (watermelon, tomato, pepper, and soybean) and subsequent pathogen transmission to seedlings was investigated. A non-pathogenic, pigmented strain of Serratia marcescens was also included to assess a null-interacting situation with the same plant species. Flowers of host and non-host plants were inoculated with 1×106 colony forming units (CFUs)/flower for each bacterial species and allowed to develop into fruits or umbels (in case of onion). Seeds harvested from each host/non-host bacterial species combination were assayed for respective bacteria by plating on semi-selective media. Additionally, seedlots for each host/non-host bacterial species combination were also assayed for pathogen transmission by seedling grow-out (SGO) assays under greenhouse conditions. The mean percentage of seedlots infested with compatible and incompatible pathogens was 31.7 and 30.9% (by plating), respectively and they were not significantly different (P = 0.67). The percentage of seedlots infested with null-interacting bacterial species was 16.8% (by plating) and it was significantly lower than the infested lots generated with compatible and incompatible bacterial pathogens (P = 0.03). None of the seedlots with incompatible/null-interacting bacteria developed symptoms on seedlings; however, when seedlings were assayed for epiphytic bacterial presence, 19.5 and 9.4% of the lots were positive, respectively. These results indicate that the seeds of non-host plants can become infested with incompatible and null-interacting bacterial species through flower colonization and they can be transmitted via epiphytic colonization of seedlings. In addition, it was also observed that flowers and seeds of non-host plants can be colonized by compatible/incompatible/null-interacting bacteria to higher populations; however, the level of colonization differed significantly depending on the type of bacterial species used. PMID:24936863

Graviresponse and its regulation from the aspect of molecular levels in higher plants: growth and development, and auxin polar transport in etiolated pea seedlings under microgravity.

PubMed

Miyamoto, Kensuke; Hoshino, Tomoki; Hitotsubashi, Reiko; Tanimoto, Eiichi; Ueda, Junichi

2003-10-01

In STS-95 space experiments we have demonstrated that microgravity conditions resulted in automorphosis in etiolated pea (Pisum sativum L. cv. Alaska) seedlings (Ueda et al. 1999). Automorphosis-like growth and development in etiolated pea seedlings were also induced under simulated microgravity conditions on a 3-dimensional (3-D) clinostat, epicotyls being the most oriented toward the direction far from the cotyledons. Detail analysis of epicotyl bending revealed that within 36 h after watering, no significant difference in growth direction of epicotyls was observed in between seedlings grown on the 3-D clinostat and under 1 g conditions, differential growth near the cotyledonary node resulting in epicotyl bending of ca. 45 degrees toward the direction far from the cotyledons. Thereafter epicotyls continued to grow almost straightly keeping this orientation on the 3-D clinostat. On the other hand, the growth direction in etiolated seedlings changed to antigravity direction by negative gravitropic response under 1 g conditions. Automorphological epicotyl bending was also phenocopied by the application of auxin polar transport inhibitors such as 9-hydroxyfluorene-9-carboxylic acid, N-(1-naphtyl)phthalamic acid and 2,3,5-triiodobenzoic acid. These results together with the fact that auxin polar transport activity in etiolated pea epicotyls was substantially reduced in space suggested that reduced auxin polar transport is closely related to automorphosis. Strenuous efforts to learn how gravity contributes to the auxin polar transport in etiolated pea epicotyls in molecular bases resulted in successful identification of PsPIN2 and PsAUX1 encoding putative auxin-efflux and influx carrier proteins, respectively. Based on the results of these gene expression under simulated microgravity conditions, a possible role of PsPIN2 and PsAUX1 genes for auxin polar transport in etiolated pea seedlings will be discussed.

Seedling growth and biomass allocation of endemic and threatened shrubs of rupestrian fields

NASA Astrophysics Data System (ADS)

Negreiros, Daniel; Fernandes, G. Wilson; Silveira, Fernando A. O.; Chalub, Clarissa

2009-03-01

The increasing anthropogenic pressure in the rare rupestrian fields in southeastern Brazil has led to the expansion of degraded areas on the extremely nutrient-deficient quartzitic soils. On the other hand, the use of rupestrian field native species in reclamation programmes has been hampered by the lack of studies involving seedling physiological ecology. The present study evaluated biomass allocation and seedling growth rate during early seedling growth of four Fabaceae shrubs: Collaea cipoensis, Calliandra fasciculata, Chamaecrista ramosa, and Mimosa foliolosa. The following hypotheses were tested: (i) species proportionally allocate higher biomass to the roots, presenting a high root/shoot ratio; and (ii) species exhibit low phenotypic variation because they have adapted to poor nutritional environments. A 12-month greenhouse experiment was carried out to evaluate seedling growth and biomass allocation performance in substrates with contrasting levels of soil fertility. The four species studied presented values of root/shoot ratio lower than one in both fertility conditions of the substrate. Growth parameters for Collaea and Calliandra increased with increasing soil fertility, while no differences were observed for Mimosa and Chamaecrista. Although the four species are naturally adapted to low nutritional quality soils, seedling development was not hindered by high fertility substrate conditions. Despite the remarkable differences in fertility between the substrates, the responsiveness in growth and allocation in Chamaecrista and Mimosa was lower than that expected if the species would exhibit high phenotypic variation. The implications for rupestrian field restoration are discussed.

Genome-wide regulation of light-controlled seedling morphogenesis by three families of transcription factors.

PubMed

Shi, Hui; Lyu, Mohan; Luo, Yiwen; Liu, Shoucheng; Li, Yue; He, Hang; Wei, Ning; Deng, Xing Wang; Zhong, Shangwei

2018-06-19

Three families of transcription factors have been reported to play key roles in light control of Arabidopsis seedling morphogenesis. Among them, bHLH protein PIFs and plant-specific protein EIN3/EIN3-LIKE 1 (EIN3/EIL1) accumulate in the dark to maintain skotomorphogenesis. On the other hand, HY5 and HY5 HOMOLOG (HYH), two related bZIP proteins, are stabilized in light and promote photomorphogenic development. To systemically investigate the transcriptional regulation of light-controlled seedling morphogenesis, we generated HY5 ox/ pifQein3eil1 , which contained mutations of EIN3/EIL1 and four PIF genes ( pifQein3eil1 ) and overexpression of HY5 Our results show that dark-grown HY5 ox/ pifQein3eil1 seedlings display a photomorphogenesis highly similar to that of wild-type seedlings grown in continuous light, with remarkably enhanced photomorphogenic phenotypes compared with the pifQ mutants. Consistent with the genetic evidence, transcriptome analysis indicated that PIFs, EIN3/EIL1, and HY5 are dominant transcription factors in collectively mediating a wide range of light-caused genome-wide transcriptional changes. Moreover, PIFs and EIN3/EIL1 independently control the expression of light-regulated genes such as HLS1 to cooperatively regulate apical hook formation, hypocotyl elongation, and cotyledon opening and expansion. This study illustrates a comprehensive regulatory network of transcription activities that correspond to specific morphological aspects in seedling skotomorphogenesis and photomorphogenesis.

Starch bioengineering affects cereal grain germination and seedling establishment

PubMed Central

Hebelstrup, Kim H.; Blennow, Andreas

2014-01-01

Cereal grain germination is central for plant early development, and efficient germination has a major role in crop propagation and malting. Endosperm starch is the prime energy reserve in germination and seedling establishment. In this study, it was hypothesized that optimized starch granule structure, and not only the endosperm starch content per se, is important for germination and seedling establishment. For that purpose, wild-type (WT), and specifically engineered degradable hyperphosphorylated (HP) starch and more resistant amylose-only (AO) starch barley lines were used. The transgenics showed no severe phenotypes and the WT and HP lines degraded the starch similarly, having 30% residual starch after 12 d of germination. However, the AO line showed significant resistance to degradation, having 57% residual starch. Interestingly, protein and β-glucan (BG) degradation was stimulated for both HP and AO lines as compared with the WT. At late seedling establishment stages, specific sugars were rapidly consumed in the AO line. α-Amylase activity was distinctly suppressed in both the HP and the AO lines. Pre-germination β-amylase deposition was low in the AO grains and β-amylase was generally suppressed in both HP and AO lines throughout germination. As further supported by scanning electron microscopy and histochemical analyses on grain and seedlings, it was concluded that inadequate starch granule deposition in combination with the suppressed hydrolase activity leads to temporal and compensating re-direction of starch, sugar, and protein catabolism important to maintain metabolic dynamics during grain germination and seedling establishment. PMID:24642850

Natural products phytotoxicity A bioassay suitable for small quantities of slightly water-soluble compounds.

PubMed

Dornbos, D L; Spencer, G F

1990-02-01

A large variety of secondary metabolites that can inhibit germination and/or seedling growth are produced by plants in low quantities. The objective of this study was to develop a bioassay capable of reliably assessing reductions in germination percentage and seedling length of small-seeded plant species caused by exposure to minute quantities of these compounds. The germination and growth of alfalfa (Medicago saliva), annual ryegrass (Lolium multiflorum), and velvetleaf (Abutilon theophrasti) were evaluated against six known phytotoxins from five chemical classes; cinmethylin (a herbicidal cineole derivative) was selected as a comparison standard. Each phytotoxin, dissolved in a suitable organic solvent, was placed on water-agar in small tissue culture wells. After the solvent evaporated, imbibed seeds were placed on the agar; after three days, germination percentages and seedling lengths were measured. Compared to a commonly used filter paper procedure, this modified agar bioassay required smaller quantities of compound per seed for comparable bioassay results. This bioassay also readily permitted the measurement of seedling length, a more sensitive indicator of phytotoxicity than germination. Seedling length decreased sigmoidally as the toxin concentration increased logarithmically. Phytotoxicity was a function of both compound and plant species. Cinmethylin, a grass herbicide, reduced the length of annual ryegrass seedlings by 90-100%, whereas that of alfalfa and velvetleaf was inhibited slightly. The agar bioassay facilitated the rapid and reliable testing of slightly water-soluble compounds, requiring only minute quantities of each compound to give reproducible results.

The effects of soil flooding on the establishment of cogongrass (Imperata cylindrica), a nonindigenous invader of the southeastern United States

USGS Publications Warehouse

King, S.E.; Grace, J.B.

2000-01-01

Cogongrass (Imperata cylindrica), an invasive perennial introduced from Southeast Asia, is currently spreading throughout the southeastern United States from Florida to Louisiana. In the U.S., cogongrass is generally not considered a wetland species, although it's range is expanding in regions with high wetland abundance. The objective of this study was to determine if excessive soil moisture might prevent cogongrass from establishing in areas with seasonally flooded soils. In one greenhouse experiment, we examined cogongrass germination and seedling growth in soils that were freely drained, saturated, and inundated. We performed a second greenhouse experiment to evaluate growth and survival of cogongrass seedlings of four different size classes in five soil moisture treatments ranging from dry to inundated. Cogongrass germination was lowest when seeds were overtopped with water. There were no differences in germination between saturated and freely drained treatments; however, seedlings grew largest in freely drained soil and were smallest when immersed. In our second experiment, most cogongrass plants survived except when given no water, but growth differed by watering treatment depending on seedling size. Increasing moisture was more detrimental to the growth of small seedlings compared to the growth of larger cogongrass plants. Overall, cogongrass was most sensitive to soil inundation in the earliest stages of establishment; thus, excessive moisture conditions in the spring, during early seedling development, could restrict invasion of cogongrass by seed. Once cogongrass is established, however, its tolerance of flooding appears to increase.

Factors influencing axillary shoot proliferation and adventitious budding in cedar.

PubMed

Renau-Morata, Begoña; Ollero, Javier; Arrillaga, Isabel; Segura, Juan

2005-04-01

We developed procedures for in vitro cloning of Cedrus atlantica Manetti and C. libani A. Rich explants from juvenile and mature plants. Explant size was one determinant of the frequency of axillary bud break in both species. Shoot tips and nodal explants mainly developed calli, whereas bud sprouting occurred in defoliated microcuttings cultured on a modified Murashige and Skoog medium without growth regulators. Isolation and continuous subculture of sprouted buds on the same medium allowed cloning of microcuttings from C. atlantica and C. libani seedlings and bicentennial C. libani trees, thus providing a desirable alternative for multiplying mature trees that have demonstrated superior characteristics. We also report adventitious bud differentiation from isolated embryos of C. atlantica. Neither auxin treatments nor other methods tested, including infection with Agrobacterium rhizogenes, were effective in inducing root initiation.

The Exoplanet Characterization ToolKit (ExoCTK)

NASA Astrophysics Data System (ADS)

Stevenson, Kevin; Fowler, Julia; Lewis, Nikole K.; Fraine, Jonathan; Pueyo, Laurent; Valenti, Jeff; Bruno, Giovanni; Filippazzo, Joseph; Hill, Matthew; Batalha, Natasha E.; Bushra, Rafia

2018-01-01

The success of exoplanet characterization depends critically on a patchwork of analysis tools and spectroscopic libraries that currently require extensive development and lack a centralized support system. Due to the complexity of spectroscopic analyses and initial time commitment required to become productive, there are currently a limited number of teams that are actively advancing the field. New teams with significant expertise, but without the proper tools, face prohibitively steep hills to climb before they can contribute. As a solution, we are developing an open-source, modular data analysis package in Python and a publicly facing web interface focused primarily on atmospheric characterization of exoplanets and exoplanet transit observation planning with JWST. The foundation of these software tools and libraries exist within pockets of the exoplanet community. Our project will gather these seedling tools and grow a robust, uniform, and well maintained exoplanet characterization toolkit.

[Seedling index of Salvia miltiorrhiza and its simulation model].

PubMed

Huang, Shu-Hua; Xu, Fu-Li; Wang, Wei-Ling; Du, Jun-Bo; Ru, Mei; Wang, Jing; Cao, Xian-Yan

2012-10-01

Through the correlation analysis on the quantitative traits and their ratios of Salvia miltiorrhiza seedlings and seedling quality, a series of representative indices reflecting the seedling quality of the plant species were determined, and the seedling index suitable to the S. miltiorrhiza seedlings was ascertained by correlation degree analysis. Meanwhile, based on the relationships between the seedling index and the air temperature, solar radiation and air humidity, a simulation model for the seedling index of S. miltiorrhiza was established. The experimental data of different test plots and planting dates were used to validate the model. The results showed that the root diameter, stem diameter, crown dry mass, root dry mass, and plant dry mass had significant positive relationships with the other traits, and could be used as the indicators of the seedling's health. The seedling index of S. miltiorrhiza could be calculated by (stem diameter/root diameter + root dry mass/crown dry mass) x plant dry mass. The stem diameter, root dry mass, crown dry mass and plant dry mass had higher correlations with the seedling index, and thus, the seedling index determined by these indicators could better reflect the seedling's quality. The coefficient of determination (R2) between the predicted and measured values based on 1:1 line was 0.95, and the root mean squared error (RMSE) was 0.15, indicating that the model established in this study could precisely reflect the quantitative relationships between the seedling index of S. miltiorrhiza and the environmental factors.

Soil propagule banks of ectomycorrhizal fungi along forest development stages after mining.

PubMed

Huang, Jian; Nara, Kazuhide; Zong, Kun; Lian, Chunlan

2015-05-01

Ectomycorrhizal fungal (EMF) propagules play an important role in seedling establishment following disturbance. However, little is known about how the EMF propagule community changes with forest development. In this study, EMF propagules were examined using seedling bioassays in rhizosphere soils collected from a recently closed Pb-Zn tailing (Taolin Pb-Zn tailing (TLT)), a Cu tailing (Dexing Cu No. 2 tailing (DXT)) that had undergone 21 years of restoration, and a mature Masson pine (Pinus massoniana) forest (DXC) outside the Cu mining areas. The corresponding EMF communities colonizing Masson pine at each site were also investigated for comparison. After 8 months of running bioassays, ectomycorrhizal colonization was poor for seedlings grown in TLT (9.0 % ± 14.9 %) and DXT soils (22.4 % ± 17.7 %), while DXC seedlings were well colonized (47.5 % ± 24.9 %). Internal transcribed spacer sequencing revealed that EMF species richness increased with forest development in both the propagule bank (TLT, 6; DXT, 7; DXC, 12) and in the field (TLT, 8; DXT, 14; DXC, 26), though richness was lower in propagule banks. Several lineages, such as Cenococcum, Rhizopogon, Inocybe, Suillus, and Atheliaceae, were frequently encountered in propagule communities, but species assemblages were different among the three sites. Canonical correspondence analysis revealed that several soil parameters, i.e., N, EC, Cu, Pb, Zn, etc., were responsible for the distribution of EMF in the field and bioassay seedlings. The highest overlap in EMF species composition between the propagule bank and the field community was observed at the recently closed tailing (Morisita-Horn similarity = 0.71 for TLT), whereas the lowest overlap occurred at the mature forest (0.26 for DXC). These results indicate that EMF propagules in soil are less frequent and diverse in early primary succession and become more frequent and diverse along forest development, due mainly to the accumulation of dormant spores of Rhizopogon spp. and sclerotia of Cenococcum spp. Thus, EMF propagule communities in soil may diverge from those root-colonizing EMF communities along a gradient of forest development.

Long-term development of regeneration under longleaf pine seedtree and shelterwood stands

Treesearch

William D. Boyer

1993-01-01

Well-stocked mature longleaf pine (Pinus palustris Mill.) stands were cut tofive residual basal areas in 1957, namely 9,18,2 7.36, and 45 ft2 per ac, to observe the effect of stand density on seed production and seedling establishment. Seedlings, mainly from the 195.5 or 1961 seed crops, were established in treated stands. All pines on net 0.9 ac...

Genetic effects on early stand development of improved loblolly pine (Pinus taeda L.) seedlings

Treesearch

S. Sharma; Joshua P. Adams; Jamie L. Schuler; Don C. Bragg; Robert L. Ficklin

2013-01-01

This study was conducted to assess the effect of genotype on the early performance of improved loblolly pine (Pinus taeda L.) seedlings planted on the University of Arkansas at Monticello School Forest located in southeast Arkansas.We used a split-plot design consisting of two spacing treatments (3.05 m × 3.05 m and 3.05 m × 4.27 m) randomly...

Shade, leaf growth, and crown development of Quercus rubra, Q. velutina, Prunus serotina, and Acer rubrum seedlings

Treesearch

Kurt W. Gottschalk

1994-01-01

The study was conducted in an open field to detennine the optimum irradiance for establishment and growth of two oak species and two major associated woody species. Half-sib seedlings of black cherry (Prunus serotina Ehrh.), red maple (Acer rubrum L.), northern red oak (Quercus rubra L.) and black oak (Q. velutina Lam.) were grown for two years under shade-clotht...

Cryptochrome 1 regulates growth and development in Brassica through alteration in the expression of genes involved in light, phytohormone and stress signalling.

PubMed

Sharma, Pooja; Chatterjee, Mithu; Burman, Naini; Khurana, Jitendra P

2014-04-01

The blue light photoreceptors cryptochromes are ubiquitous in higher plants and are vital for regulating plant growth and development. In spite of being involved in controlling agronomically important traits like plant height and flowering time, cryptochromes have not been extensively characterized from agriculturally important crops. Here we show that overexpression of CRY1 from Brassica napus (BnCRY1), an oilseed crop, results in short-statured Brassica transgenics, likely to be less prone to wind and water lodging. The overexpression of BnCRY1 accentuates the inhibition of cell elongation in hypocotyls of transgenic seedlings. The analysis of hypocotyl growth inhibition and anthocyanin accumulation responses in BnCRY1 overexpressors substantiates that regulation of seedling photomorphogenesis by cry1 is dependent on light intensity. This study highlights that the photoactivated cry1 acts through coordinated induction and suppression of specific downstream genes involved in phytohormone synthesis or signalling, and those involved in cell wall modification, during de-etiolation of Brassica seedlings. The microarray-based transcriptome profiling also suggests that the overexpression of BnCRY1 alters abiotic/biotic stress signalling pathways; the transgenic seedlings were apparently oversensitive to abscisic acid (ABA) and mannitol. © 2013 John Wiley & Sons Ltd.

Seedling mortality in Hawaiian rain forest: The role of small-scale physical disturbance

USGS Publications Warehouse

Drake, D.R.; Pratt, L.W.

2001-01-01

Most montane rain forests on the island of Hawaii consist of a closed canopy formed by Cibotium spp. tree ferns beneath an open canopy of emergent Metrosideros polymorpha trees. We used artificial seedlings to assess the extent to which physical disturbance caused by the senescing fronds of tree ferns and the activities of feral pigs might limit tree regeneration. Artificial seedlings were established terrestrially (N = 300) or epiphytically (N = 300) on tree fern stems. Half of the seedlings on each substrate were in an exclosure lacking feral pigs and half were in forest with pigs present. After one year, the percentage of seedlings damaged was significantly greater among terrestrial seedlings (25.7%) than epiphytic seedlings (11.3%). Significantly more terrestrial seedlings were damaged in the presence of pigs (31.3%) than in the absence of pigs (20.0%). Senescing fronds of tree ferns were responsible for 60.3 percent of the damaged seedlings. Physical disturbance is potentially a major cause of seedling mortality and may reduce the expected half-life of a seedling cohort to less than two years.

Post-fire vegetation succession in Mediterranean gorse shrublands

NASA Astrophysics Data System (ADS)

De Luis, Martin; Raventós, José; González-Hidalgo, José Carlos

2006-07-01

In Western Mediterranean areas, forest fires are frequent in forests established on old croplands where post-fire regeneration is limited to obligate-seeder species. This has resulted in the spread of Mediterranean gorse ( Ulex parviflorus) increasing the risk and severity of fires. The aim of this paper is to test the autosuccessional hypothesis on a Mediterranean gorse shrubland dominated by seeders species. Particular objectives are: a) to analyze the effect of fire on seedling emergence, survival and growth on the main species involved on plant regeneration process. b) to identify changes in the relative abundance of species as consequence of fire by using a before-after experiment. Then, after experimental fires, seedling emergence, survival and growth rates were analyzed for the main species present in the vegetation regeneration process. Our results show that Mediterranean gorse communities are dominated by Fabaceae species (64% of individuals, mainly of Ulex parviflorus). However, our study demonstrates that vegetation regeneration after fire does not display an autosuccessional pattern and is produced a change on dominance from Fabaceae (mainly U. parviflorus) to Cistaceae (mainly C. albidus) species. Cistaceae seedlings (mainly Cistus albidus and Helianthemum marifolium) were the most abundant post-fire (63% of total germination) while species of Fabaceae (including U. parviflorus and Ononis fruticosa) represented 25%, and Lamiaceae (restricted to Rosmarinus officinalis) comprised only 3% of total emergences. Seedling survival did not differ significantly from one species to another (25-30% of initial individuals over 3 years) but seedling growth rates were also higher for Cistaceae than for Fabaceae individuals. Then, after fire, in terms of biomass, Fabaceae presence decreased from 78.7% to 13.1% while Cistaceae increase from 8% to 83.4%. Given that fire frequency, intensity or severity is partially controlled by the composition and structure of the plant community population changes in the main species, could affect the future fire regime and in turn, affect the hydrological, ecological and economic role of a large stretch of forest and woodland areas in western Mediterranean ecosystems.

Germination and initial growth of tree seedlings on deforested and natural forest soil at Dulhazara, Bangladesh.

PubMed

Hossain, M Mohitul

2012-12-01

The destruction of natural forest is increasing due to urbanization, industrialization, settlement and for the agricultural expansion over last few decades, and studies for their recovery need to be undertaken. With this aim, this comparative study was designed to see the effects of deforested soil on germination and growth performance of five different tree species. In the experiment, five species namely Gmelina arborea, Swietenia mahagoni, Dipterocarpus turbinatus, Acacia auriculiformis and Syzygium grande were germinated for six weeks on seedbeds and raised in pots (25cm diameter, 30cm height), that were filled with two soil and type of land use: deforested and adjacent natural forest of Dulhazara Safari Park. Growth performance of seedling was observed up to 15 months based on height, collar diameter and biomass production at the end. Our results showed that the germination rate was almost similar in both type of land uses. Height growth of D. turbinatus, G. arborea and S. mahagoni seedlings was almost similar and A. auriculi formis and S. grande lower in deforested soil compared to natural forest soil, while collar diameter ofA. auriculi formis, G. arborea, S. grande and S. mahagoni lower and D. turbinatus similar in deforested soil compared to natural forest soil. After uprooting at 19 months, S. mahagoni seedlings were showed significantly (p< or =0.05) higher oven dry biomass, D. turbinatus and A. auriculiformis higher, while G. arborea showed significantly (p< or =0.05) lower and S. grande almost similar oven dry biomass in deforested soil compared to natural forest soil. Oven dry biomass of D. turbinatus seedlings at 19 month age in deforested soil was 21.96g (n=5) and in natural forest soil 18.86g (n=5). However, differences in germination rate and growth performance for different tree species indicated that soil are not too much deteriorated through deforestation at Dulhazara and without any failure such deforested lands would be possible to bring under forest through plantation.

Cytoplasmic Calcium Increases in Response to Changes in the Gravity Vector in Hypocotyls and Petioles of Arabidopsis Seedlings1

PubMed Central

Toyota, Masatsugu; Furuichi, Takuya; Tatsumi, Hitoshi; Sokabe, Masahiro

2008-01-01

Plants respond to a large variety of environmental signals, including changes in the gravity vector (gravistimulation). In Arabidopsis (Arabidopsis thaliana) seedlings, gravistimulation is known to increase the cytoplasmic free calcium concentration ([Ca2+]c). However, organs responsible for the [Ca2+]c increase and the underlying cellular/molecular mechanisms remain to be solved. In this study, using Arabidopsis seedlings expressing apoaequorin, a Ca2+-sensitive luminescent protein in combination with an ultrasensitive photon counting camera, we clarified the organs where [Ca2+]c increases in response to gravistimulation and characterized the physiological and pharmacological properties of the [Ca2+]c increase. When the seedlings were gravistimulated by turning 180°, they showed a transient biphasic [Ca2+]c increase in their hypocotyls and petioles. The second peak of the [Ca2+]c increase depended on the angle but not the speed of rotation, whereas the initial peak showed diametrically opposite characters. This suggests that the second [Ca2+]c increase is specific for changes in the gravity vector. The potential mechanosensitive Ca2+-permeable channel (MSCC) inhibitors Gd3+ and La3+, the Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA), and the endomembrane Ca2+-permeable channel inhibitor ruthenium red suppressed the second [Ca2+]c increase, suggesting that it arises from Ca2+ influx via putative MSCCs in the plasma membrane and Ca2+ release from intracellular Ca2+ stores. Moreover, the second [Ca2+]c increase was attenuated by actin-disrupting drugs cytochalasin B and latrunculin B but not by microtubule-disrupting drugs oryzalin and nocodazole, implying that actin filaments are partially involved in the hypothetical activation of Ca2+-permeable channels. These results suggest that the second [Ca2+]c increase via MSCCs is a gravity response in the hypocotyl and petiole of Arabidopsis seedlings. PMID:18055589

[Physiological responses of mycorrhizal Pinus massoniana seedlings to drought stress and drought resistance evaluation].

PubMed

Wang, Yi; Ding, Gui-jie

2013-03-01

A greenhouse pot experiment was conducted to study the effects of inoculating Pisolithus tinctorius, Cenococcum geophilum, Cantharellus cibarius, and Suillus luteus on the physiological characteristics of Pinus massoniana seedlings under the conditions of drought stress and re-watering, with the drought resistance of the mycorrhizal seedlings evaluated. Under drought stress, the MDA content and membrane' s relative permeability of P. massoniana seedlings increased, but these two indices in the inoculated (mycorrhizal) seedlings were significantly lower than these in the un-inoculated (control) seedlings. After re-watering, the MDA content and membrane's relative permeability of mycorrhizal seedlings had a rapid decrease, as compared with the control. In the first 21 days of drought stress, the production rate of superoxide radical of the seedlings increased, and the SOD, POD and NR activities of mycorrhizal seedlings increased significantly. With the extending of drought stress, the seedlings after re-watering had different recovery ability. Under the re-watering after 14 days drought stress, the SOD, POD and NR activities recovered. The drought resistance of the mycorrhizal seedlings was in the order of Suillus luteus 1 > Suillus luteus 7 > Cantharellus cibarius > Cenococcum geophilum > Pisolithus tinctorius. The SOD and MDA activities had a greater correlation with the mycorrhizal seedlings drought resistance, being able to be used as the indicators to evaluate the drought resistance of mycorrhizal seedlings.