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

Ten-year growth response of young Douglas-fir to variable density varnishleaf ceanothus and herb competition

USGS Publications Warehouse

Monleon, V.J.; Newton, M.; Hooper, C.; Tappeiner, J. C.

1999-01-01

The effect of different densities of varnishleaf ceanothus (Ceanothus velutinus var. laevigatus) and herbaceous vegetation control on stem diameter, height, and volume of plantation Douglas-fir (Pseudotsuga menziesii var. menziesii) seedlings was examined during the 10 yr following planting. Initial densities of ceanothus ranged between 0 and 15,000 seedlings/ha and were obtained by interplanting ceanothus germinants or chemical thinning after clearcutting and broadcast-burning. Herbaceous vegetation control was achieved by a single application of glyphosate following planting, with shrub seedlings covered. Ceanothus density in the range of 0 to 6,750 plants/ha did not have an effect on Douglas-fir diameter, height, or volume at age 10; however, Douglas-fir growth was significantly decreased when ceanothus densities reached 15,000 plants/ha. Ten years after planting, Douglas-fir volume in the treatments with 6,750 ceanothus/ha or less was 1.7 times greater than that in the 15,000 ceanothus/ha treatment. On the other hand, removal of herbaceous vegetation after planting significantly increased tree diameter, height, and volume, regardless of ceanothus density. Even 10 yr after the application of the treatment, trees without early herb competition grew faster and had mean dbh, height, and volume that were 1.02 cm, 0.55 m, and 12.98 dm3/tree greater respectively than those with herbs. Thus, a treatment at plantation establishment to control herbaceous vegetation and to reduce ceanothus density to less than 7,000 plants/ha will ensure an increase in growth and stocking for at least 10 yr.

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

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...

Air lateral root pruning affects longleaf pine seedling root system morphology

Treesearch

Shi-Jean Susana Sung; Dave Haywood

2016-01-01

Longleaf pine (Pinus palustris) seedlings were cultured with air lateral root pruning (side-vented containers, VT) or without (solid-walled containers, SW). Seedling root system morphology and growth were assessed before planting and 8 and 14 months after planting. Although VT seedlings had greater root collar diameter than the SW before planting,...

Nursery quality and first-year response of american chestnut (Castanea dentata) seedlings planted in the southeastern United States

Treesearch

Stacy L. Clark; Callie J. Schweitzer; Scott E. Schlarbaum; Luben D. Dimov; Frederick V. Hebard

2010-01-01

We examined nursery seedling quality and 1-yr field performance of American chestnut [Castanea dentata (Marshall) Borkh.] seedlings planted in Alabama (AL study) and Tennessee (TN study). Root-collar diameter (RCD) had the highest correlations to nursery seedling quality and first-year fleld performance for both studies. Survival was low in the...

Devices to protect seedlings from deer browsing

Treesearch

David A. Marquis

1977-01-01

Studies on the Allegheny Plateau of Pennsylvania have shown that several types of wire or plastic tubes can be erected around tree seedlings to protect them from deer browsing. The two most promising devices are a 4- to 6-inch diameter plastic tube with small mesh and a 12-inch diameter tube constructed of chicken wire. Both types need to be at least 5 feet tall to...

Sucrose metabolism and growth in transplanted loblolly pine seedlings

Treesearch

Shi-Jean S. Sung; C.C. Black; Paul P. Kormanik

1993-01-01

Loblolly pine (Pinus taeda L.) seedling height, root collar diameter, and the specific activities of three sucrose metabolizing enzymes, namely, sucrose synthase (SS), acid invertase, and neutral invertase, were measured to assess seedling responses to transplant stress. It was concluded that i) SS was the dominant enzyme for sucrose metabolism in...

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

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...

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...

Evaluation of Four Herbicides and Tillage for Weed Control on 1-0 Planted Tree Seedlings

Treesearch

John R. Seifert; Keith Woeste

2002-01-01

Azafenidin, sulfometuron, pendimethalin, and simazine were applied alone and in combination to 1-0 seedlings of nine hardwood and one conifer species. Percent bare ground at 30, 60, and 90 days, diameter and height growth of the seedlings were determined for 16 herbicide treatments, tillage and a control. Azafenidin applications alone and in combination with...

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...

Interspecific Competition and Trade-offs in Resource Allocation are the Key to Successful Growth of Seedlings of White Spruce (Picea glauca (Moench) Voss) at Subarctic Treelines in Warming Alaska.

NASA Astrophysics Data System (ADS)

Okano, K.; Bret-Harte, M. S.

2015-12-01

Alpine treelines in Alaska have advanced for the past 50 years in response to the recent climate warming. However, further increases in temperatures may cause treeline species drought stress and increase susceptibility to insect outbreaks and fire. Complex factors such as soil conditions and plant species composition also impact the growth of seedlings, which are essential to sustain boreal forests. Our goals were to assess 1) the current optimal elevation for the treeline species Picea glauca (white spruce) seedlings and how it is altered by climate change, and 2) their growth/survival strategies at each environmental site. We studied the growth response of spruce seedlings along an altitudinal gradient at 6 sites, consisting of tundra, forest, or transitional ecotone in Denali National Park and one forest site in Fairbanks, AK. In May 2012, four-month old seedlings were planted with or without naturally occurring plants to compare the presence or absence of the interspecific interaction. Summer temperatures were increased by one small greenhouse per site. Over 2 growing seasons, growth was measured non-destructively, and then the seedlings were harvested. Relative growth rate (RGR) in height was increased significantly as the altitude was increased. Elevated temperature increased height only in seedlings at a high-altitude forest. Seedlings with neighboring plants had a higher RGR in height than seedlings that had neighbors removed, while significantly wider diameters were measured from the seedlings without neighbors. A weak trend of declining diameter width with increasing altitudes was seen. Seedlings that grew taller did not grow their stems wider, indicating trade-offs in resource allocation. None of the altitudinal sites had a clear advantage for the growth of the seedlings. Habitat microclimate and the interaction with other species could be more important than the altitude or temperatures and hence, key to the survival and growth of spruce seedlings in this region.

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.

Interactive effects of substrate, hydroperiod, and nutrients on seedling growth of Salix nigra and Taxodium distichum

USGS Publications Warehouse

Day, Richard H.; Doyle, T.W.; Draugelis-Dale, R. O.

2006-01-01

The large river swamps of Louisiana have complex topography and hydrology, characterized by black willow (Salix nigra) dominance on accreting alluvial sediments and vast areas of baldcypress (Taxodium distichum) deepwater swamps with highly organic substrates. Seedling survival of these two wetland tree species is influenced by their growth rate in relation to the height and duration of annual flooding in riverine environments. This study examines the interactive effects of substrate, hydroperiod, and nutrients on growth rates of black willow and baldcypress seedlings. In a greenhouse experiment with a split-split-plot design, 1-year seedlings of black willow and baldcypress were subjected to two nutrient treatments (unfertilized versus fertilized), two hydroperiods (continuously flooded versus twice daily flooding/draining), and two substrates (sand versus commercial peat mix). Response variables included height, diameter, lateral branch count, biomass, and root:stem ratio. Black willow growth in height and diameter, as well as all biomass components, were significantly greater in peat substrate than in sand. Black willow showed a significant hydroperiod-nutrient interaction wherein fertilizer increased stem and root biomass under drained conditions, but flooded plants did not respond to fertilization. Baldcypress diameter and root biomass were higher in peat than in sand, and the same two variables increased with fertilization in flooded as well as drained treatments. These results can be used in Louisiana wetland forest models as inputs of seedling growth and survival, regeneration potential, and biomass accumulation rates of black willow and baldcypress.

[Effects of forest canopy gap on Abies faxoniana seedling's biomass and its allocation in sub-alpine coniferous forest of West Sichuan].

PubMed

Xian, Jun-Ren; Hu, Ting-Xing; Zhang, Yuan-Bin; Wang, Kai-Yun

2007-04-01

By the method of strip transect sampling, the density, height, basal diameter, and components biomass of Abies faxoniana seedlings (H < or = 100 cm) lived in the forest gap (FG) and under the forest canopy (FC) of subalpine natural coniferous forest in West Sichuan were investigated, and the relationships among different components biomass were analyzed. The results indicated that the density and average height (H) of A. faxoniana seedlings were significantly different in FG and under FC, with the values being 12 903 and 2 017 per hectare, and 26.6 cm and 24.3 cm, respectively, while no significant differences were found in average basal diameter (D) and biomass. The biomass allocation in seedling's components was markedly affected by forest gap. In FG, the biomass ratio of branch to trunk (BRBT) reached the maximum (1.54) at 12th year, and then, declined and fluctuated at 0. 69. Under FC, the BRBT was increased with seedlings growth, and exceeded 1.0 at about 15th year. The total biomass and the biomass of leaf, stem, shoot and root grown in FG and under FC were significantly linearly correlated with D2H. There were significant positive correlations among the biomass of different seedling's components.

Locust sprouts reduce growth of yellow-poplar seedlings

Treesearch

Donald E. Beck; Charles E. McGee

1974-01-01

Dense thickets of black locust which often appear after clearcutting in the Southern Appalachians and Piedmont, can severely reduce growth of other desirable hardwoods. Released yellow-poplar seedlings were 51 percent taller and 79 percent larger in diameter than unreleased ones 6 years after treatment.

Release Accelerates Growth of Yellow-Poplar -- an 18-Year Look

Treesearch

Robert D. Williams

1976-01-01

Yellow-poplar seedlings that germinated and were completely released from woody competition in 1957 (the first year after a harvest cut) were four times taller and five times larger in diameter after the 1973 growing season than seedlings that were not released.

Growth and Chemical Responses to CO2 Enrichment Virginia Pine (Pinus Virginiana Mill.) (NDP-009)

DOE Data Explorer

Luxmoore, R. J. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (USA); Norby, R. J. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (USA); O'Neill, E. G. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (USA); Weller, D. G. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (USA); Ells, J. M. [Agricultural Research Service, USDA; North Carolina State University, Raleigh, NC (USA); Rogers, H. H. [Agricultural Research Service, USDA; North Carolina State University, Raleigh, NC (USA)

1985-01-01

From June 28 to October 29 in 1982, Virginia pine seedlings were exposed to elevated CO2 levels in open-top growth chambers at one of four concentrations (75, 150, 300, and 600 ppm above ambient). Plant dry weight; height; stem diameter; and chemical contents of leaf, stem, and root tissues were measured before and after exposure. Soil variables were also characterized. These data illustrate the short-term physical and chemical response of Virginia pine seedlings to elevated levels of CO2. The data are in seven files: initial dry weights before exposure (844 kB), dry weights after exposure (4 kB), major nutrient concentrations after final harvest (12 kB), minor nutrient concentrations after final harvest (17 kB), soil nutrient concentrations after final harvest (4 kB), soil leachate elements after final harvest (5 kB), and soil leachate solutes after final harvest (4 kB).

Effects of Post-Fire Plant Cover in the Performance of Two Cordilleran Cypress (Austrocedrus chilensis) Seedling Stocktypes Planted in Burned Forests of Northeastern Patagonia, Argentina.

PubMed

Urretavizcaya, María F; Gonda, Héctor E; Defossé, Guillermo E

2017-03-01

Cordilleran cypress (Austrocedrus chilensis [D.Don] Pic. Serm. et Bizarri) forests occupy 140,000 ha along a sharp environmental gradient of central Andean-Patagonia in Argentina. Every summer, about 3200 ha of these forests are affected by wildfires, taking thereafter long time to recover. To accelerate forest recovery, we determined in xeric and mesic cypress stands burned 5 and 2 year before whether survival and growth of two planted cypress seedling stocktypes are affected by plant cover and contrasting precipitation conditions. Two experiments were conducted on each site, involving 100 replicates of two seedling stocktypes, having each significantly different morphological attributes. The experiments comprised a dry and humid growing season on each site. Both stocktypes performed similarly within stands, but differently between stands. In the xeric stand, plant cover had neutral effects on seedling survival, favored seedling height growth in the dry season, and was negative on collar diameter and stem growth. In the mesic site, high plant cover favored survival and height growth, but was inconsequential for collar diameter and stem growth. In this short-term post-fire period, and independent of precipitation received during both seasons (dry or humid), plant cover appears as playing a facilitative role, having neutral or even positive effects on survival and growth of planted seedlings. During the early post-fire successional stages, and besides seedling stocktype, there was a synergistic balance between light and soil moisture that seems to benefit planted seedling performance in burned cypress forests, and especially in mesic sites.

Effects of Post-Fire Plant Cover in the Performance of Two Cordilleran Cypress ( Austrocedrus chilensis) Seedling Stocktypes Planted in Burned Forests of Northeastern Patagonia, Argentina

NASA Astrophysics Data System (ADS)

Urretavizcaya, María F.; Gonda, Héctor E.; Defossé, Guillermo E.

2017-03-01

Cordilleran cypress ( Austrocedrus chilensis [D.Don] Pic. Serm. et Bizarri) forests occupy 140,000 ha along a sharp environmental gradient of central Andean-Patagonia in Argentina. Every summer, about 3200 ha of these forests are affected by wildfires, taking thereafter long time to recover. To accelerate forest recovery, we determined in xeric and mesic cypress stands burned 5 and 2 year before whether survival and growth of two planted cypress seedling stocktypes are affected by plant cover and contrasting precipitation conditions. Two experiments were conducted on each site, involving 100 replicates of two seedling stocktypes, having each significantly different morphological attributes. The experiments comprised a dry and humid growing season on each site. Both stocktypes performed similarly within stands, but differently between stands. In the xeric stand, plant cover had neutral effects on seedling survival, favored seedling height growth in the dry season, and was negative on collar diameter and stem growth. In the mesic site, high plant cover favored survival and height growth, but was inconsequential for collar diameter and stem growth. In this short-term post-fire period, and independent of precipitation received during both seasons (dry or humid), plant cover appears as playing a facilitative role, having neutral or even positive effects on survival and growth of planted seedlings. During the early post-fire successional stages, and besides seedling stocktype, there was a synergistic balance between light and soil moisture that seems to benefit planted seedling performance in burned cypress forests, and especially in mesic sites.

Regeneration dynamics during oak decline with prescribed fire in the Boston Mountains of Arkansas

Treesearch

Martin A. Spetich

2013-01-01

Northern red oak (Quercus rubra L.) seedlings were inventoried in 2000 and again in 2005 to better understand survival of advance regeneration during oak decline. In 2000, basal stem diameter was measured and recorded for 861 individually tagged seedlings that were

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...

Container longleaf pine seedling morphology in response to varying rates of nitrogen fertilization in the nursery and subsequent growth after outplanting

Treesearch

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

2007-01-01

A fertilization rate of 2 or 3 mg nitrogen (N) per week for 20 weeks yielded longleaf pine (Pinus palustris) seedlings grown inside a greenhouse that survived well and produced good root collar diameter (RCD) growth the first year after outplanting. Of a range of fertilization rates (0.5 to 4 mg N/week), the 2 mg rate yielded seedlings that did not...

Tree seedlings respond to both light and soil nutrients in a Patagonian evergreen-deciduous forest.

PubMed

Promis, Alvaro; Allen, Robert B

2017-01-01

Seedlings of co-occurring species vary in their response to resource availability and this has implications for the conservation and management of forests. Differential shade-tolerance is thought to influence seedling performance in mixed Nothofagus betuloides-Nothofagus pumilio forests of Patagonia. However, these species also vary in their soil nutrient requirements. To determine the effects of light and soil nutrient resources on small seedlings we examined responses to an experimental reduction in canopy tree root competition through root trenching and restricting soil nutrient depletion through the addition of fertilizer. To understand the effect of light these treatments were undertaken in small canopy gaps and nearby beneath undisturbed canopy with lower light levels. Seedling diameter growth was greater for N. pumilio and height growth was greater for N. betuloides. Overall, diameter and height growth were greater in canopy gaps than beneath undisturbed canopy. Such growths were also greater with fertilizer and root trenching treatments, even beneath undisturbed canopy. Seedling survival was lower under such treatments, potentially reflecting thinning facilitated by resource induced growth. Finally, above-ground biomass did not vary among species although the less shade tolerant N. pumilio had higher below-ground biomass and root to shoot biomass ratio than the more shade tolerant N. betuloides. Above- and below-ground biomass were higher in canopy gaps so that the root to shoot biomass ratio was similar to that beneath undisturbed canopy. Above-ground biomass was also higher with fertilizer and root trenching treatments and that lowered the root to shoot biomass ratio. Restricting soil nutrient depletion allowed seedlings of both species to focus their responses above-ground. Our results support a view that soil nutrient resources, as well as the more commonly studied light resources, are important to seedlings of Nothofagus species occurring on infertile soils.

Competition-Induced Reductions in Soil Water Availability Reduced Pine Root Extension Rates

Treesearch

K.H. Ludovici; L.A. Morris

1997-01-01

The relationship between soil water availability, root extension, and shoot growth of loblolly pine seedlings (Pinus taeda L.) was evaluated in a rhizotron sand mixture in the absence and presence of crabgrass (Digitaria spp.) competition. Heights and diameters of seedlings grown with crabgrass were reduced 33 and SO%, respectively, compared with...

Mosaic stunting in bareroot Pinus banksiana seedlings is unrelated to colonization by mycorrhizal fungi

Treesearch

Lynette R. Potvin; Martin F. Jurgensen; R. Kasten Dumroese; Dana L. Richter; Deborah S. Page-Dumroese

2014-01-01

Mosaic stunting, the occurrence of random patches of chlorotic seedlings with reduced shoot and diameter growth amidst more robust cohorts within bareroot nurseries, is classically associated with poor colonization by mycorrhizal fungi. We examined possible relationships among soil fertility, mycorrhizas, and random patches of mosaic stunting in bareroot Pinus...

Survival and growth of hardwood seedlings following preplanting-root treatments and treeshelters

Treesearch

Felix, Jr. Ponder

1997-01-01

The study evaluated the influence of root collar diameter, number of large lateral roots, preplanting-root treatments (biostimulant called Roots and a moisture loss retardant called supersorb) and tree shelters on 1-0 black walnut (Juglans nigra L.) and northern red oak (Quercus rubra L.) seedlings. Four years after outplanting,...

Food reserves and seasonal growth of Douglas-fir seedlings.

Treesearch

Kenneth W. Krueger; James M. Trappe

1967-01-01

Seasonal growth of tops and roots and concomitant trends in food reserves were observed biweekly on Peudotsuga menzisii (Mirb.) Franco seedlings of two seed sources growing in a Pacific Northwest forest nursery. A general pattern of alternating root, diameter, and shoot growth was found. Rapid root growth did not coincide with rapid shoot...

Evaluation of Rhizophora Mucronata Growth at first-year Mangrove Restoration at Abandoned Ponds, Langkat, North Sumatra

NASA Astrophysics Data System (ADS)

Basyuni, M.; Telaumbanua, TFC; Wati, R.; Sulistyono, N.; Putri, LAP

2018-03-01

Degraded mangrove areas can be restored and rehabilitated. In Indonesia, one of the main recommended of mangrove species for restoration of degraded was Rhizophora mucronata. The purpose of the study was to evaluate R. mucronata growth at first-year mangrove restoration at abandoned shrimp ponds, Pulau Sembilan village, Langkat, North Sumatera, Indonesia. The recovery area divided into three zones based on the salinity concentration, landward, middle, and seaward zones. The evaluation parameters of mangrove reforestation consist of seedling diameter and height, leaves number, and seedling growth rate. Results showed that 3 of 4 evaluation parameters of R. mucronata growth belong to landward zone, namely seedlings diameter, the number of leaves, and percentage of growth. By contrast, height R. mucronata seedlings dominated in the middle area. The study also found that the proper zone for mangrove restoration with R. mucronata was in the landward with 96% growth rate and 30 part per thousand salinity concentration. The present study, therefore, suggested that the recommended species for the degraded area was the prerequisite for successful mangrove restoration.

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...

Soil Water Effects on Blue Oak Seedling Establishment

Treesearch

Doria R. Gordon; Kevin J. Rice; Jeffrey M. Welker

1991-01-01

A field experiment was conducted to examine the effects of soil water availability on blue oak (Quercus douglasii) seedling establishment. Acorns were planted either into cleared plots of 0, 10, 20, or 40 cm diameter. The cleared plots were located in two grazed and one ungrazed site. Half of the plots received drip irrigation in a split plot design...

Influence of Fire on Oak Seedlings and Saplings in Southern Oak Woodland on the Santa Rosa Plateau Preserve, Riverside County, California

Treesearch

Earl W. Lathrop; Chris D. Osborne

1991-01-01

One wildfire and two prescription burns were monitored at 15 oak seedling/sapling regeneration sites and at four non-burned comparison sites to study the effect of fire on seedlings and saplings of Quercus engelmannii (Engelmann oak) and Q. agrifolia (coast live oak). The number of initial topkilled seedlings and saplings, initial...

Stock size affects early growth of a loblolly pine

Treesearch

David B. South; Al Lyons; Russ Pohl

2015-01-01

For decades, forest researchers in the South have known that early gains in survival and growth of loblolly pine (Pinus taeda L.) can be achieved by planting large-diameter seedlings (South 1993; Wakeley 1949). For P. radiata, increasing size of planting stock also increases early growth of both seedlings (Mason and others 1996) and cuttings (South and others 2005)....

The density effect: Red/far red signaling and douglas-fir seedling growth in a variable density field test

Treesearch

Gary A. Ritchie; James Keeley; Barbara J. Bond

2007-01-01

Coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings, when planted in a reforestation setting, exhibit early height and diameter growth that is inversely proportional to planting density. One hypothesis to explain this observation is that they are able to detect the presence of nearby trees using phytochrome by sensing the ratio of...

Stock Type Affects Performance of Shortleaf Pine Planted in the Ouachita Mountains Through 10 Years

Treesearch

James P. Barnett; John C. Brissette

2004-01-01

Shortleaf pine (Pinus echinata Mill.) seeds collected from several half-sib families were grown as both bare-root and container stock and outplanted on two sites in the Ouachita Mountains of Arkansas. When outplanted, the bare-root seedlings had greater mean height and root-collar diameter than the container seedlings. However, the container...

Effect of simulated insect damage on growth and survival of northern red oak (Quercus rubra L.) seedlings

Treesearch

Susan L. Wright; Richard W. Hall; John W. Peacock

1989-01-01

Effects of simulated insect damage—artificial defoliation and root damage in combination with two levels of watering—were studied to determine the potential effect on northern red oak seedlings (Quercus rubra L.). Treatments and treatment combinations caused significant differences in stem diameter, percentage of stem dieback, and mortality....

Mechanical site preparation and oust XP effects on stem biomass in three-year-old nuttall oak seedlings planted on a former agricultural field

Treesearch

Andrew B. Self; Andrew W. Ezell; Dennis Rowe; Emily B. Schultz; John D. Hodges

2015-01-01

Mechanical site preparation is frequently proposed to alleviate problematic soil conditions when afforesting retired agricultural fields. Without management of soil problems, any seedlings planted in these areas may exhibit poor growth and survival. Seeding height and groundline diameter are often used to evaluate effects of site preparation methods, but stem biomass...

A method for estimating the preharvest potential for seeding height growth on cutover forest land in southwestern Oregon.

Treesearch

Don. Minore

1986-01-01

Diameter growth of young trees as measured on Douglas-fir stumps of the previous stand was related to height of 5-year-old Douglas-fir seedlings on 16 cable-yarded, broadcast-burned progeny test plantations in southwestern Oregon. The resulting regression can be used to estimate the preharvest potential for seedling height growth on cutover land.

Effects of EDU and Ozoban on the growth of shortleaf pine seedlings in the field

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

Flagler, R.B.; Lock, J.E.

Two field studies were conducted to determine the response of shortleaf pine seedlings planted in the field to ethylenediurea (EDU) and sodium erythorbate (Ozoban), both of which possess antioxidant properties, and were developed to protect plants from ozone (O[sub 3]). Seedlings originated from two half-sib families of shortleaf pine, S2PE3 and S3PE9, and a third [open quotes]woods-run[close quotes] selection. For the EDU study, the chemical treatment levels were 0 and 300 ppm EDU. For the Ozoban study, the chemical treatment levels were 0, 515, 1030, 1545, and 2060 ppm Ozoban. Seedlings were sprayed monthly with the appropriate concentration of antioxidantmore » chemical for two years. EDU increased leaf area and foliage, stem and root biomass for all three selections; the response of the woods-run selection was the greatest. Height growth was increased by EDU only in the woods-run selection. Diameter growth was not affected by EDU. In the Ozoban study, only family S2PE3 exhibited a biomass response to Ozobon, with increased biomass as Ozoban application rate increased up to the highest rat, at which point there was a small decrease. Height growth was not affected by Ozoban. Diameter growth of the woods-run selection increased as Ozoban applications rate increased, with a slight decrease at the highest application rate. Diameter of the other selections was not affected by Ozoban. Both chemicals appeared to provide some protection to shortleaf pine against ambient O[sub 3].« less

Functional diversity in gravitropic reaction among tropical seedlings in relation to ecological and developmental traits.

PubMed

Alméras, Tancrède; Derycke, Morgane; Jaouen, Gaëlle; Beauchêne, Jacques; Fournier, Mériem

2009-01-01

Gravitropism is necessary for plants to control the orientation of their axes while they grow in height. In woody plants, stem re-orientations are costly because they are achieved through diameter growth. The functional diversity of gravitropism was studied to check if the mechanisms involved and their efficiency may contribute to the differentiation of height growth strategies between forest tree species at the seedling stage. Seedlings of eight tropical species were grown tilted in a greenhouse, and their up-righting movement and diameter growth were measured over three months. Morphological, anatomical, and biomechanical traits were measured at the end of the survey. Curvature analysis was used to analyse the up-righting response along the stems. Variations in stem curvature depend on diameter growth, size effects, the increase in self-weight, and the efficiency of the gravitropic reaction. A biomechanical model was used to separate these contributions. Results showed that (i) gravitropic movements were based on a common mechanism associated to similar dynamic patterns, (ii) clear differences in efficiency (defined as the change in curvature achieved during an elementary diameter increment for a given stem diameter) existed between species, (iii) the equilibrium angle of the stem and the anatomical characters associated with the efficiency of the reaction also differed between species, and (iv) the differences in gravitropic reaction were related to the light requirements: heliophilic species, compared to more shade-tolerant species, had a larger efficiency and an equilibrium angle closer to vertical. This suggests that traits determining the gravitropic reaction are related to the strategy of light interception and may contribute to the differentiation of ecological strategies promoting the maintenance of biodiversity in tropical rainforests.

Repeated manual release in a young plantation: effect on Douglas-fir seedlings, hardwoods, shrubs, forbs, and grasses.

Treesearch

Philip M. McDonald; Gary O. Fiddler; Henry Harrison

1994-01-01

Douglas-fir seedlings on the Arcata Resource Area, Bureau of Land Management, U.S. Department of the Interior, in central coastal California, were released by chain sawing and grubbing competing vegetation around them at different frequencies (0, 2, and 3 grubbings) over a 5-year period. After 5 years, average Douglas-fir stem diameter (measured at 12 inches above mean...

Survival, growth, and acornet production of artificially regenerated northern red oak on two high-quality mesic sites at year seven

Treesearch

Paul P. Kormanik; Shi-Jean Susana Sung; Taryn L. Kormanik; Stanley J. Zarnoch; Catharine D. Cook; Tom Tibbs; Scott E. Schlarbaum

2006-01-01

Open-pollinated, half-sib northern red oak (Quercus rubra L.) 1-0 seedlings were grown under an improved nursery protocol. Minimum seedling grading standards for this test were six first-order lateral roots, 8-cm root-collar diameter, and 0.7-m height. At the Brasstown site on a salvage clearcut in North Georgia, we spot-applied glyphosate herbicide...

Effects of Botryosphaeria Inoculation and Stress During Lifting and Outplanting on Initial Growth of Outplanted Sweetgum Seedlings

Treesearch

William Carey; Dave Gerwig; Bert Cregg; Scott Enebak

2004-01-01

A coordinated investigation was carried out with sweetgum seedlings from a nursery in South Carolina (SC) and one in Virginia (VA) to evaluate the effects of cultural practices and Botryosphaeria on the establishment and initial growth of transplanted sweetgum. Seedlings from VA were more sensitive to treatments than those from SC, and date of leaf emergence after...

Immature Loblolly Pine Growth and Biomass Accumulation: Correlations with Seedlings Initial First-Order Lateral Roots

Treesearch

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

1998-01-01

Five to seven years after being graded by first-order lateral root (FOLR) numbers and outplanted, loblolly pine (Pinus taeda L.) seedlings were excavated using a commercial tree spade and root systems reevaluated. Current competitive position of trees was related to initial FOLR numbers of 1-0 seedlings. Current FOLR numbers were comparable among tree size classes, but...

Root development of acorn-origin oak seedlings in shelterwood stands on the Appalachian Plateau of northern Pennsylvania: 4-year results

Treesearch

Patrick H. Brose

2008-01-01

Post-fire sprouting of oak seedlings in prescribe-burned shelterwood stands hinges on their root collar diameters exceeding 6.4 mm and root size depends on the type of partial cut and the time since harvest. To better understand this shelterwood stage/time/oak root size relationship, a study was begun in northern Pennsylvania in 2001. Acorns of black, chestnut,...

Lanthanum Affects Bell Pepper Seedling Quality Depending on the Genotype and Time of Exposure by Differentially Modifying Plant Height, Stem Diameter and Concentrations of Chlorophylls, Sugars, Amino Acids, and Proteins.

PubMed

García-Jiménez, Atonaltzin; Gómez-Merino, Fernando C; Tejeda-Sartorius, Olga; Trejo-Téllez, Libia I

2017-01-01

Lanthanum (La) is considered a beneficial element, capable of inducing hormesis. Hormesis is a dose-response relationship phenomenon characterized by low-dose stimulation and high-dose inhibition. Herein we tested the effect of 0 and 10 μM La on growth and biomolecule concentrations of seedlings of four sweet bell pepper ( Capsicum annuum L.) varieties, namely Sven, Sympathy, Yolo Wonder, and Zidenka. Seedling evaluations were performed 15 and 30 days after treatment applications (dat) under hydroponic greenhouse conditions. Seedling height was significantly increased by La, growing 20% taller in Yolo Wonder plants, in comparison to the control. Similarly, La significantly enhanced shoot diameter, with increases of 9 and 9.8% in measurements performed 15 and 30 dat, respectively, as compared to the control. Likewise, La-treated seedlings had a higher number of flower buds than the control. An increase in the number of leaves because of La application was observed in Yolo Wonder seedlings, both 15 and 30 dat, while leaf area was augmented in this variety only 30 dat. Nevertheless, La did not affect dry biomass accumulation. La effects on biomolecule concentration were differential over time. In all varieties, La stimulated the biosynthesis of chlorophyll a, b and total 15 dat, though 30 dat only the varieties Sympathy and Yolo Wonder showed enhanced concentrations of these molecules because of La. Total soluble sugars increased in La-treated seedlings 30 dat. Interestingly, while most varieties exposed to La showed a reduction in amino acid concentration 15 dat, the opposite trend was observed 30 dat. Importantly, in all varieties evaluated, La stimulated soluble protein concentration 30 dat. It is important to note that while chlorophyll concentrations increased in all varieties exposed to La, both 15 and 30 dat, those of soluble sugars and proteins consistently increased only 30 dat, but not 15 dat. Our results confirm that La may improve seedling quality by enhancing some growth parameters and biomolecule concentrations, depending on the genotype, and time of exposure.

Influence of nitrogen and phosphorous on the growth and root morphology of Acer mono

PubMed Central

Zhang, Peng; Shen, Hai-long; Salahuddin

2017-01-01

Nitrogen and phosphorous are critical determinants of plant growth and productivity, and both plant growth and root morphology are important parameters for evaluating the effects of supplied nutrients. Previous work has shown that the growth of Acer mono seedlings is retarded under nursery conditions; we applied different levels of N (0, 5, 10, and 15 g plant-1) and P (0, 4, 6 and 8 g plant-1) fertilizer to investigate the effects of fertilization on the growth and root morphology of four-year-old seedlings in the field. Our results indicated that both N and P application significantly affected plant height, root collar diameter, chlorophyll content, and root morphology. Among the nutrient levels, 10 g N and 8 g P were found to yield maximum growth, and the maximum values of plant height, root collar diameter, chlorophyll content, and root morphology were obtained when 10 g N and 8 g P were used together. Therefore, the present study demonstrates that optimum levels of N and P can be used to improve seedling health and growth during the nursery period. PMID:28234921

Facilitative and inhibitory effect of litter on seedling emergence and early growth of six herbaceous species in an early successional old field ecosystem.

PubMed

Li, Qiang; Yu, Pujia; Chen, Xiaoying; Li, Guangdi; Zhou, Daowei; Zheng, Wei

2014-01-01

In the current study, a field experiment was conducted to examine effects of litter on seedling emergence and early growth of four dominant weed species from the early successional stages of old field ecosystem and two perennial grassland species in late successional stages. Our results showed that increased litter cover decreased soil temperature and temperature variability over time and improved soil moisture status. Surface soil electrical conductivity increased as litter increased. The increased litter delayed seedling emergence time and rate. The emergence percentage of seedlings and establishment success rate firstly increased then decreased as litter cover increased. When litter biomass was below 600 g m(-2), litter increased seedlings emergence and establishment success in all species. With litter increasing, the basal diameter of seedling decreased, but seedling height increased. Increasing amounts of litter tended to increase seedling dry weight and stem leaf ratio. Different species responded differently to the increase of litter. Puccinellia tenuiflora and Chloris virgata will acquire more emergence benefits under high litter amount. It is predicted that Chloris virgata will dominate further in this natural succession old field ecosystem with litter accumulation. Artificial P. tenuiflora seeds addition may be required to accelerate old field succession toward matured grassland.

Facilitative and Inhibitory Effect of Litter on Seedling Emergence and Early Growth of Six Herbaceous Species in an Early Successional Old Field Ecosystem

PubMed Central

Li, Qiang; Yu, Pujia; Chen, Xiaoying; Li, Guangdi; Zhou, Daowei; Zheng, Wei

2014-01-01

In the current study, a field experiment was conducted to examine effects of litter on seedling emergence and early growth of four dominant weed species from the early successional stages of old field ecosystem and two perennial grassland species in late successional stages. Our results showed that increased litter cover decreased soil temperature and temperature variability over time and improved soil moisture status. Surface soil electrical conductivity increased as litter increased. The increased litter delayed seedling emergence time and rate. The emergence percentage of seedlings and establishment success rate firstly increased then decreased as litter cover increased. When litter biomass was below 600 g m−2, litter increased seedlings emergence and establishment success in all species. With litter increasing, the basal diameter of seedling decreased, but seedling height increased. Increasing amounts of litter tended to increase seedling dry weight and stem leaf ratio. Different species responded differently to the increase of litter. Puccinellia tenuiflora and Chloris virgata will acquire more emergence benefits under high litter amount. It is predicted that Chloris virgata will dominate further in this natural succession old field ecosystem with litter accumulation. Artificial P. tenuiflora seeds addition may be required to accelerate old field succession toward matured grassland. PMID:25110722

Toxic effect of cadmium adsorbed by different sizes of nano-hydroxyapatite on the growth of rice seedlings.

PubMed

Huang, Yifan; Qiu, Weiwen; Yu, Zhihong; Song, Zhengguo

2017-06-01

Information regarding the toxic effects of cadmium (Cd) adsorbed by nano-hydroxyapatite (NHAP-Cd) on the growth of crop plants remain limited. We investigated the mechanism of NHAP-Cd (diameters, 20 and 40nm; NHAP 20 -Cd and NHAP 40 -Cd, respectively) phytotoxicity. Rice seedlings treated with Cd and NHAP 20 -Cd showed more severe growth retardation compared to those treated with NHAP 40 -Cd, for the same Cd concentration. Transmission electron microscopy revealed NHAP in the seedlings. The nanoparticles entered the rice seedlings with no Cd 2+ signals in the NHAP treatments compared to -0.47pmolcm -2 s -1 of Cd 2+ fluxes in the Cd treatment. The higher Cd 2+ content in the leaves and mesocotyl of NHAP 20 -Cd-treated rice seedlings suggested that smaller NHAP-Cd can translocate easily to the aboveground parts. Further, NHAP-Cd increased oxidative stress, which was determined as catalase activity changes in this study. Thus, NHAP-Cd particles in the growth medium can be transported to rice seedlings and cause toxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

Growth reponses of eggplant and soybean seedlings to mechanical stress in greenhouse and outdoor environments

NASA Technical Reports Server (NTRS)

Latimer, J. G.; Pappas, T.; Mitchell, C. A.

1986-01-01

Eggplant (Solanum melongena L. var. esculentum 'Burpee's Black Beauty') and soybean [Glycine max (L.) Merr. 'Wells II'] seedlings were assigned to a greenhouse or a windless or windy outdoor environment. Plants within each environment received either periodic seismic (shaking) or thigmic (flexing or rubbing) treatment, or were left undisturbed. Productivity (dry weight) and dimensional (leaf area and stem length) growth parameters generally were reduced more by mechanical stress in the greenhouse (soybean) or outdoor-windless environment (eggplant) than in the outdoor windy environment. Outdoor exposure enhanced both stem and leaf specific weights, whereas mechanical stress enhanced only leaf specific weight. Although both forms of controlled mechanical stress tended to reduce node and internode diameters of soybean, outdoor exposure increased stem diameter.

Genotype and elevation influence Spartina alterniflora colonization and growth in a created salt marsh

USGS Publications Warehouse

Proffitt, C.E.; Travis, S.E.; Edwards, K.R.

2003-01-01

Colonization, growth, and clonal morphology differ with genotype and are influenced by elevation. Local adaptation of Spartina alterniflora to environmental conditions may lead to dominance by different suites of genotypes in different locations within a marsh. In a constructed marsh, we found reduced colonization in terms of density of clones with increasing distance from edge in a 200-ha mudflat created in 1996; however, growth in diameter was not different among three 100-m-long zones that differed in distance from site edge. Distance from edge was confounded by elevation in this comparison of natural colonization. The rate of clonal expansion in diameter was 3.1 m/yr, and clonal growth was linear over the 28 mo of the study. The area dominated by S. alterniflora in the three distance zones increased concomitantly with clonal growth. However, the lower initial clonal densities and colonization by other plant species resulted in reduced overall dominance by S. alterniflora in the two more-interior locations. Seedling recruitment was an important component of S. alterniflora colonization at all elevations and distances from edge two years after site creation. Seedlings were spatially very patchy and tended to occur near clones that probably produced them. A field experiment revealed that S. alterniflora height and total stem length varied with genotype, while stem density and flowering stem density did not. Differences between edge and center of clonal patches also occurred for some response variables, and there were also significant interactions with genotype. Differences between edge and center are interpreted as differences in clone morphology. Elevation differences over distances of a few meters influenced total stem length and flowering stem density but not other response variables. Clones that were larger in diameter also tended to have greater stem heights and total stem lengths. A number of plant morphological measures were found to vary significantly among the five genotypes and had broad-sense heritabilities ranging up to 0.71. These results indicate that S. alterniflora populations developing on new substrata colonize broadly, but growth and reproduction vary with genotype and are influenced by changes in elevation (range: 11.8 cm), and probably other environmental factors, over relatively small distances. Differences in growth and clone morphology of different genets, and the frequent occurrence of seedlings throughout the site, underscore the importance of genetic variability in natural and created populations.

Evaluation of mangrove reforestation and the impact to socioeconomic-cultural of community in Lubuk Kertang village, North Sumatra

NASA Astrophysics Data System (ADS)

Basyuni, M.; Harahap, MA; Wati, R.; Slmaet, B.; Thoha, AS; Nuryawan, A.; Putri, LAP; Yusriani, E.

2018-03-01

Mangrove forests in North Sumatera existed in the east coast of Sumatera Island and are rapidly threatened due to anthropogenic activities such as conversion for aquaculture, oil palm plantation, filling and use of mangrove for urban development. The present study describes the current and first-year evaluation on mangrove restoration and its impact to socio economic-cultural of community in Lubuk Kertang village, Langkat, North Sumatra, Indonesia. The rehabilitation was carried on December 2015 using direct planting of 6,000 Rhizophora apiculata propagules and May 2016 using 5,000 R. apiculata seedlings. The evaluation parameters of mangrove reforestation consist of seedling diameter and height, leaf thickness and number, and seedling growth rate. Ninety-two of 1,124 households were surveyed using Slovin formula to obtain community perspective on the socio-economic-cultural impact of reforestation. Results show that the growth rate for current and first-year evaluation was 93 and 86 %, respectively. By contrast, the height, diameter, and some leaves seedlings planting were shown better than the performance of propagules planting. No change in the green foliage plant thickness between both farming methods. The reforestation affected 71.74, 55.43 and 39.13% of economic, social, and cultural of Lubuk Kertang community, respectively. The data is likely to provide valuable information for mangrove reforestation in North Sumatra.

Drought stress leads to systemic induced susceptibility to a nectrotrophic fungus associated with mountain pine beetle in Pinus banksiana seedlings.

PubMed

Klutsch, Jennifer G; Shamoun, Simon Francis; Erbilgin, Nadir

2017-01-01

Conifers have complex defense responses to initial attacks by insects and pathogens that can have cascading effects on success of subsequent colonizers. However, drought can affect a plant's ability to respond to biotic agents by potentially altering the resources needed for the energetically costly production of induced defense chemicals. We investigated the impact of reduced water on induced chemical defenses of jack pine (Pinus banksiana) seedlings from initial attack by biotic agents and resistance to subsequent challenge inoculation with a pathogenic fungal associate of mountain pine beetle (Dendroctonus ponderosae), Grosmannia clavigera. Applications of phytohormones (methyl salicylate and methyl jasmonate) and G. clavigera were used for initial induction of defenses. Monoterpene concentrations varied with initial induction from fungal and phytohormone application while watering treatment had no effect. Seedlings treated with G. clavigera and methyl jasmonate had the greatest monoterpene concentrations compared to the control and methyl salicylate-treated seedlings. However, the monoterpene response to the challenge inoculation varied with watering treatments, not with prior induction treatments, with lower monoterpene concentrations in fungal lesions on seedlings in the low to moderate watering treatments compared to normal watering treatment. Furthermore, prior induction from phytohormones resulted in systemic cross-induction of resistance to G. clavigera under normal watering treatment but susceptibility under low watering treatment. Seedlings stressed by low water conditions, which also had lower stomatal conductance than seedlings in the normal watering treatment, likely allocated resources to initial defense response but were left unable to acquire further resources for subsequent responses. Our results demonstrate that drought can affect interactions among tree-infesting organisms through systemic cross-induction of susceptibility.

Drought stress leads to systemic induced susceptibility to a nectrotrophic fungus associated with mountain pine beetle in Pinus banksiana seedlings

PubMed Central

Shamoun, Simon Francis; Erbilgin, Nadir

2017-01-01

Conifers have complex defense responses to initial attacks by insects and pathogens that can have cascading effects on success of subsequent colonizers. However, drought can affect a plant’s ability to respond to biotic agents by potentially altering the resources needed for the energetically costly production of induced defense chemicals. We investigated the impact of reduced water on induced chemical defenses of jack pine (Pinus banksiana) seedlings from initial attack by biotic agents and resistance to subsequent challenge inoculation with a pathogenic fungal associate of mountain pine beetle (Dendroctonus ponderosae), Grosmannia clavigera. Applications of phytohormones (methyl salicylate and methyl jasmonate) and G. clavigera were used for initial induction of defenses. Monoterpene concentrations varied with initial induction from fungal and phytohormone application while watering treatment had no effect. Seedlings treated with G. clavigera and methyl jasmonate had the greatest monoterpene concentrations compared to the control and methyl salicylate-treated seedlings. However, the monoterpene response to the challenge inoculation varied with watering treatments, not with prior induction treatments, with lower monoterpene concentrations in fungal lesions on seedlings in the low to moderate watering treatments compared to normal watering treatment. Furthermore, prior induction from phytohormones resulted in systemic cross-induction of resistance to G. clavigera under normal watering treatment but susceptibility under low watering treatment. Seedlings stressed by low water conditions, which also had lower stomatal conductance than seedlings in the normal watering treatment, likely allocated resources to initial defense response but were left unable to acquire further resources for subsequent responses. Our results demonstrate that drought can affect interactions among tree-infesting organisms through systemic cross-induction of susceptibility. PMID:29216258

Research challenges for structural use of small-diameter round timbers

Treesearch

Ron Wolfe

2000-01-01

Forest managers have identified forest stands overstocked with small-diameter trees as a critical forest health issue. Overstocked stands are subject to attack by insects and disease and, as a result of the heavy fuel load, risk total destruction by fire. Prescribed burning is an economic tool for suppressing the growth of brush and tree seedlings, but its use is often...

Double-planting can affect gains from weed control treatments

Treesearch

David B. South

2010-01-01

Double-planting is the practice of planting two seedlings at every planting spot. When both seedlings survive, then either the less vigorous seedling is removed or each seedling is given an equal chance of being removed. Some researchers double-plant so that tree growth among experimental plots is not affected by initial differences in stocking. However, double-...

Effect of advance seedling size and vigor on survival after clearcutting

Treesearch

David A. Marquis

1982-01-01

In several separate experiments, it was found that survival of advance seedlings after clearcutting in Allegheny hardwood stands is a function of initial seedling size-larger seedlings survive best. Age, number of leaves, and leaf size also were important determinants of survival. In Allegheny hardwood stands, where advance regeneration is typically less than 1 foot in...

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...

A rapid decrease in temperature induces latewood formation in artificially reactivated cambium of conifer stems

PubMed Central

Begum, Shahanara; Nakaba, Satoshi; Yamagishi, Yusuke; Yamane, Kenichi; Islam, Md. Azharul; Oribe, Yuichiro; Ko, Jae-Heung; Jin, Hyun-O; Funada, Ryo

2012-01-01

Background and Aims Latewood formation in conifers occurs during the later part of the growing season, when the cell division activity of the cambium declines. Changes in temperature might be important for wood formation in trees. Therefore, the effects of a rapid decrease in temperature on cellular morphology of tracheids were investigated in localized heating-induced cambial reactivation in Cryptomeria japonica trees and in Abies firma seedlings. Methods Electric heating tape and heating ribbon were wrapped on the stems of C. japonica trees and A. firma seedlings. Heating was discontinued when 11 or 12 and eight or nine radial files of differentiating and differentiated tracheids had been produced in C. japonica and A. firma stems, respectively. Tracheid diameter, cell wall thickness, percentage of cell wall area and percentage of lumen area were determined by image analysis of transverse sections and scanning electron microscopy. Key Results Localized heating induced earlier cambial reactivation and xylem differentiation in stems of C. japonica and A. firma as compared with non-heated stems. One week after cessation of heating, there were no obvious changes in the dimensions of the differentiating tracheids in the samples from adult C. japonica. In contrast, tracheids with a smaller diameter were observed in A. firma seedlings after 1 week of cessation of heating. Two or three weeks after cessation of heating, tracheids with reduced diameters and thickened cell walls were found. The results showed that the rapid decrease in temperature produced slender tracheids with obvious thickening of cell walls that resembled latewood cells. Conclusions The results suggest that a localized decrease in temperature of stems induces changes in the diameter and cell wall thickness of differentiating tracheids, indicating that cambium and its derivatives can respond directly to changes in temperature. PMID:22843340

Nitrogen levels, top pruning, and lifting date affect nursery development and early field performance of loblolly pine seedlings

Treesearch

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

1999-01-01

Loblolly pine seedling nursery development and 3-year field performance were contrasted between two nitrogen (N) application regimes and comparable top pruning regimes. Other initial soil nutritional elements were comparable, but high N seedlings received 150 lb/acre N (as NH4NO3) and low N seedlings received half this...

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...

[Effects of precipitation and interspecific competition on Quercus mongolica and pinus koraiensis seedlings growth].

PubMed

Wu, Jing-Lian; Wang, Miao; Lin, Fei; Hao, Zhan-Qing; Ji, Lan-Zhu; Liu, Ya-Qin

2009-02-01

Aiming at the variation of precipitation pattern caused by global warming, a field simulation experiment was conducted to study the effects of 30% increase (+W) and decrease (-W) of precipitation on the morphology, growth, and biomass partitioning of mono- and mixed cultured seedlings of Quercus mongolica and Pinus koraiensis, the two dominant tree species in temperate broad-leaved Korean pine mixed forest in Changbai Mountains. Comparing with monoculture, mixed culture increased the canopy width and main root length of Q. mongolica seedlings, but decreased the basal diameter, plant height, leaf number, and dry masses of root, stem, leaf and whole plant of P. koraiensis seedlings significantly. Treatment (-W) increased the stem/mass ratio while decreased the main root length of Q. mongolica seedlings, and decreased the main root length, leaf number, dry masses of leaf and whole plant, and leaf/mass ratio, while increased the stem/mass ratio of P. koraiensis seedlings significantly, compared with treatment CK. Treatment (+W) had no significant effect on these indices of the two species. At early growth stage, interspecific competition and precipitation pattern had significant effects on the morphology and growth of the seedlings, and the responses were much stronger for P. koraiensis than for Q. mongolica.

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...

[Effects of different endophytic fungi on seedling growth of Dendrobium devonianum].

PubMed

Huang, Hui; Shao, Shi-Cheng; Gao, Jiang-Yun

2016-06-01

To obtain seedling growth-promoting fungi is a key step in restoration-friendly cultivation of medicinal Dendrobium species, since there are a large number of functionally-unknown endophytic fungi in the roots of Dendrobium plants.In this study, six functionally-unknown endophytic fungal strains were isolated from roots of D.devonianum using single peleton isolation technology, and used in inoculation experiments to test their effectiveness for seedling growth in D.devonianum.After 90 days of inoculation, comparing with the control treatment, FDdS-1, FDdS-2 and FDdS-4 showed strong pathogenic or fatal effects on seedlings; while, FDdS-12, FDdS-9 and FDdS-5 had different effects on seedling growth.FDdS-5 had significant promoting effects on height, fresh and dry weight, stem diameter and root numbers, while FDdS-9 only had significant promoting effect on seedling height, and FDdS-12 had a negative effect on seedling growth.According to the anatomical features of the inoculated roots, FDdS-5 fungi could infect the velamina of seedlings and the existence of symbiosis pelotons in the cortex cells, suggesting that FDdS-5 is a mycorrhiza fungi of D.devonianum.FDdS-5 and FDdS-9 were identified as Sebacina vermifera and Sebacina sp.by molecular technologies.By using FDdS-5 in the restoration-friendly cultivation of D.devonianum, it could effectively promote seedling growth and shorten the seedling growth periods.The results will aid in reintroduction and cultivation of D.devonianum. Copyright© by the Chinese Pharmaceutical Association.

Response of antioxidant defense system to laser radiation apical meristem of Isatis indigotica seedlings exposed to UV-B.

PubMed

Chen, Yi-Ping

2009-07-01

To determine the response of antioxidant defense system to laser radiation apical meristem of Isatis indigotica seedlings, Isatis indigotica seedlings were subjected to UV-B radiation (10.08 kJ m(-2)) for 8 h day(-1) for 8 days (PAR, 220 micromol m(-2) s(-1)) and then exposed to He-Ne laser radiation (633 nm; 5.23 mW mm(-2); beam diameter: 1.5 mm) for 5 min each day without ambient light radiation. Changes in free radical elimination systems were measured, the results indicate that: (1) UV-B radiation enhanced the concentration of Malondialdahyde (MDA) and decreased the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in seedlings compared with the control. The concentration of MDA was decreased and the activities of SOD, CAT and POD were increased when seedlings were subjected to elevated UV-B damage followed by laser; (2) the concentration of UV absorbing compounds and proline were increased progressively with UV-B irradiation, laser irradiation and He-Ne laser irradiation plus UV-B irradiation compared with the control. These results suggest that laser radiation has an active function in repairing UV-B-induced lesions in seedlings.

The role of genetic and chemical variation of Pinus sylvestris seedlings in influencing slug herbivory.

PubMed

O'Reilly-Wapstra, Julianne M; Iason, Glenn R; Thoss, Vera

2007-05-01

This study investigated the genetic and chemical basis of resistance of Pinus sylvestris seedlings to herbivory by a generalist mollusc, Arion ater. Using feeding trials with captive animals, we examined selective herbivory by A. ater of young P. sylvestris seedlings of different genotypes and correlated preferences with seedling monoterpene levels. We also investigated the feeding responses of A. ater to artificial diets laced with two monoterpenes, Delta(3)-carene and alpha-pinene. Logistic regression indicated that two factors were the best predictors of whether seedlings in the trial would be consumed. Individual slug variation (replicates) was the most significant factor in the model; however, alpha-pinene concentration (also representing beta-pinene, Delta(3)-carene and total monoterpenes due to multicollinearity) of needles was also a significant factor. While A. ater did not select seedlings on the basis of family, seedlings not eaten were significantly higher in levels of alpha-pinene compared to seedlings that were consumed. We also demonstrated significant genetic variation in alpha-pinene concentration of seedlings between different families of P. sylvestris. Nitrogen and three morphological seedling characteristics (stem length, needle length and stem diameter) also showed significant genetic variation between P. sylvestris families. Artificial diets laced with high (5 mg g(-1) dry matter) quantities of either Delta(3)-carene or alpha-pinene, were eaten significantly less than control diets with no added monoterpenes, supporting the results of the seedling feeding trial. This study demonstrates that A. ater selectively feed on P. sylvestris seedlings and that this selection is based, in part, on the monoterpene concentration of seedlings. These results, coupled with significant genetic variation in alpha-pinene concentration of seedlings and evidence that slug herbivory is detrimental to P. sylvestris fitness, are discussed as possible evidence for A. ater as a selective force on the evolution of defensive chemistry in P. sylvestris.

Elevated CO2 and O3 effects on fine-root survivorship in ponderosa pine mesocosms.

PubMed

Phillips, Donald L; Johnson, Mark G; Tingey, David T; Storm, Marjorie J

2009-07-01

Atmospheric carbon dioxide (CO(2)) and ozone (O(3)) concentrations are rising, which may have opposing effects on tree C balance and allocation to fine roots. More information is needed on interactive CO(2) and O(3) effects on roots, particularly fine-root life span, a critical demographic parameter and determinant of soil C and N pools and cycling rates. We conducted a study in which ponderosa pine (Pinus ponderosa) seedlings were exposed to two levels of CO(2) and O(3) in sun-lit controlled-environment mesocosms for 3 years. Minirhizotrons were used to monitor individual fine roots in three soil horizons every 28 days. Proportional hazards regression was used to analyze effects of CO(2), O(3), diameter, depth, and season of root initiation on fine-root survivorship. More fine roots were produced in the elevated CO(2) treatment than in ambient CO(2). Elevated CO(2), increasing root diameter, and increasing root depth all significantly increased fine-root survivorship and median life span. Life span was slightly, but not significantly, lower in elevated O(3), and increased O(3) did not reduce the effect of elevated CO(2). Median life spans varied from 140 to 448 days depending on the season of root initiation. These results indicate the potential for elevated CO(2) to increase the number of fine roots and their residence time in the soil, which is also affected by root diameter, root depth, and phenology.

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...

[Allelopathy of grape root aqueous extracts].

PubMed

Li, Kun; Guo, Xiu-wu; Guo, Yin-shan; Li, Cheng-xiang; Xie, Hong-gang; Hu, Xi-xi; Zhang, Li-heng; Sun, Ying-ni

2010-07-01

Taking the tissue-cultured seedlings of grape cultivar Red Globe as test objects, this paper examined the effects of their root aqueous extracts on seedling's growth, with the allelochemicals identified by LC-MS. The results showed that 0.02 g x ml(-1) (air-dried root mass in aqueous extracts volume; the same below), 0.1 g x ml(-1), and 0.2 g x ml(-1) of the aqueous extracts inhibited the growth of the seedlings significantly, and the inhibition effect increased with increasing concentration of the extracts. The identified allelochemicals of the extracts included p-hydroxybenzoic acid, salicylic acid, phenylpropionic acid, and coumaric acid. Pot experiment showed that different concentration (0.1, 1, and 10 mmol x L(-1)) salicylic acid and phenylpropionic acid inhibited the seedling' s growth remarkably. With the increasing concentration of the two acids, the plant height, stem diameter, shoot- and root fresh mass, leaf net photosynthetic rate and starch content, and root activity of the seedlings decreased, while the leaf soluble sugar and MDA contents increased. No obvious change pattern was observed in leaf protein content.

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,...

[Effects of acid rain stress on Eleocarpus glabripetalus seedlings leaf chlorophyll fluorescence characteristics and growth].

PubMed

Yin, Xiu-Min; Yu, Shu-Quan; Jiang, Hong; Liu, Mei-Hu

2010-06-01

A pot experiment was conducted to study the Eleocarpus glabripetalus seedlings leaf chlorophyll fluorescence characteristics and growth in different seasons under simulated acid rain stress (heavy, pH = 2. 5; moderate, pH = 4.0; and control, pH = 5.6). In the same treatments, the leaf relative chlorophyll content (SPAD), maximum PS II photochemical efficiency (F(v)/F(m)), actual PSII photochemical quantum yield (phi(PS II)), plant height, and stem diameter in different seasons were all in the order of October > July > April > January. In the same seasons, all the parameters were in the order of heavy acid rain > moderate acid rain > control. The interactions between different acid rain stress and seasons showed significant effects on the SPAD, F(v)/F(m), plant height, and stem diameter, but lesser effects on phi(PS II), qp and qN.

[Effect of ectomycorrhizae on the growth of Picea koraiensis seedlings].

PubMed

Song, Rui-Qing; Wu, Ke

2005-12-01

Basidioscarps of Agaricales in different Picea koraiensis forest plantations were collected during August-October, 2000. 36 isolaters of species of Agaricales were obtained by isolating and culturing to the basidioscarps. Through indoor inoculation test on seedlings of Picea koraiensis, 6 ectomycorrhizae fungi cultures were obtained from 36 isolaters. The inoculation results show that the period for ectomycorrhizae inoculation to 1-year seedlings of Picea koraiensis should be about 30 days after seedlings emerging, the suitable temperature for ectomycorrhizae forming is about 20 degrees C. 6 ectomycorrhizae strains all have growth-promoting effect to the seedlings of Picea koraiensis. The contents of chlorophyll a of the seedlings inoculated strains of Agaricus silvaticus, 031 and L15 were significantly higher than other strains and control. The contents of chlorophyll b in the seedlings inoculated strains 009, 004, Agaricus silvaticus and L15 were significantly higher than other strains and control. The weights of seedlings which inoculated strains 009, 025, 031, Agaricus silvaticus and L15 were significantly different to control, the weight of seedlings inoculated strains of Agaricus silvaticus and L15 are 19.23% and 23.08% more than control; The heights of the seedlings inoculated 6 strains all have significant difference to control, the weight of seedlings inoculated strains of Agaricus silvaticus and L15 are 17.83% and 16.37% more than control. The results of outdoor inoculation show that the seedlings inoculated Agaricus silvaticus grow best on height, 9.25% more than control after inoculated 70 days; the seedlings inoculated strain L15 grow best on collar diameter, 9.92% more than control after inoculated 70 days; the lateral root numbers of seedlings inoculated strain 009 is largest, 51.91% more than control after inoculated 70 days; the main roots of seedlings inoculated strain 009 are longest, 3.36% more than control after inoculated 70 days; the ectomycorrhizae fungi infestation percentage of seedlings inoculated strain 031 is highest, 13.90% more than control after inoculated 70 days; the photosynthesis of seedlings inoculated strain 031 is more powerful, 20.02% more than control after inoculated 70 days. To sum up, strain 009, strain 031 and strain L15 should be fine strains to seedlings of Picea koraiensis.

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...

Growth and physiological responses of beech seedlings to long-term exposure of acid fog.

PubMed

Shigihara, Ado; Matsumoto, Kiyoshi; Sakurai, Naoki; Igawa, Manabu

2008-02-25

Seven-year-old beech seedlings (Fagus crenata) were exposed to simulated acid fog (SAF) at pH 3 or pH 5 (as control) prepared by adding a 2:1:1 mixture (molar ratio) of nitric acid, ammonium sulfate, and sodium chloride to ultrapure water from September 2004 to July 2006 in a mobile fog chamber. In comparison to control seedlings, seedlings from the pH 3 treatment displayed inferior plant height, stem diameter, number of leaves, and dry matter production, but greater leaf area. Furthermore, exposure to SAF induced early falling of leaves with a nearly two-times-greater normalized leaf number index than control. The starch levels in the stems of seedlings of the pH 3 treatment were much lower than those of control at the harvest. The acid fog-induced reduction of the starch accumulation is considered to occur mainly because of fewer leaves during the growth phase. Results of laboratory experiments demonstrate that the amount of base cations leached from the beech leaves increased with decreasing pH of SAF; the leaching amount of calcium ion from the beech was high relative to that of conifers such as fir and cedar. These results imply that chronic acid fog exposure suppresses growth and physiological activity of beech seedlings.

Nursery Cultural Practices and Morphological Attributes of Longleaf Pine Bare-Root Stock as Indicators of Early Field Performance

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

Glyndon E. Hatchell, Research Forester, Retired Institute for Mycorrhizal Research and Development Athens, Georgia and H. David Muse, Professor Department of Mathematics University of North Alabama Florence, Alabama

1990-02-01

A large study of morphological attributes of longleaf pine nursery stock at the Savannah River site of the various attributes measured, only number of lateral roots and seedling diameters were related to performance. Lateral root pruning in the nursery also improved performance. Both survival and growth during the first two years were strongly correlated with larger stem diameter and larger root system development.

Phytotoxicity of carbon nanotubes in soybean as determined by interactions with micronutrients

NASA Astrophysics Data System (ADS)

Zaytseva, Olga; Wang, Zhengrui; Neumann, Günter

2017-02-01

Carbon nanomaterials released into the environment exert extremely variable effects on living organisms. In this study, we used soybean ( Glycine max) to investigate early responses to seed exposure to multi-walled carbon nanotubes (MWCNTs, outer diameter 20-70 nm, inner diameter 5-10 nm, length of >2 μm). Soybean seeds were imbibed with deionised water (control) or MWCNT suspension (1000 mg L-1) and were analysed for MWCNT contamination using light microscopy. The seedlings vitality status was evaluated by staining with triphenyltetrazolium chloride and measurement of oxidative stress indicators in the root tissue. Micronutrient (Zn, Mn, Cu) availability in different seedling organs was assessed and the effects of antioxidants, and micronutrient supplementation was investigated. Oxidative stress induction by MWCNTs was detectable in radicle tips, coincided with MWCNTs accumulation and was reverted by external application of proline as antioxidant and micronutrients (Zn, Cu, Mn) as cofactors for various enzymes involved in oxidative stress defence. Accordingly, SOD activity increased after Zn supplementation. During germination, the MWCNT treatments reduced Zn translocation from the cotyledons to the seedling and MWCNTs exhibited adsorption potential for Zn and Cu, which may be involved in internal micronutrients immobilisation. This study demonstrates for the first time that MWCNT phytotoxicity is linked with oxidative stress-related disturbances of micronutrient homeostasis.

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...

Individual and interactive effects of white-tailed deer and an exotic shrub on artificial and natural regeneration in mixed hardwood forests

PubMed Central

Owings, Charlotte F.; Jacobs, Douglass F.; Shields, Joshua M.; Saunders, Michael R.

2017-01-01

Abstract Underplanting tree seedlings in areas where natural regeneration is limited may offer a tool by which desired overstory composition can be maintained or restored in forests. However, invasive plant species and ungulate browsing may limit the effectiveness of underplanting, and in-turn, the successful restoration of forest ecosystems. Individually, the invasive shrub Lonicera maackii and browsing by white-tailed deer (Odocoileus virginianus) have been found to negatively affect the regeneration of native tree species in the Midwestern United States, but few studies have examined their interactive or cumulative effects. Using exclosures and shrub removal at five sites, we examined the effects of white-tailed deer and L. maackii both on underplanted seedlings of Castanea dentata and Quercus rubra and on the composition, species richness and diversity of naturally regenerated native tree seedlings. Individually, both deer and L. maackii had negative effects on the survival of underplanted seedlings, but we identified no interactive effects. The presence of L. maackii or deer alone resulted in similar declines in the survivorship of Q. rubra seedlings, but the presence of deer alone resulted in lower survival of C. dentata seedlings than the presence of L. maackii alone. Lonicera maackii reduced light levels, increased seedling moisture stress and decreased relative basal diameter growth for Q. rubra seedlings. Deer reduced the relative growth in height of underplanted C. dentata and Q. rubra seedlings and increased moisture stress of C. dentata seedlings. No effects of L. maackii or deer were found on soil or foliar nitrogen or the overall abundance, species richness and diversity of naturally regenerated seedlings. However, L. maackii and white-tailed deer did affect the abundance of individual tree species, shifting composition of the regeneration layer towards shade tolerant and unpalatable and/or browse tolerant species. PMID:28721187

Factors affecting acorn production and germination and early growth of seedlings and seedling sprouts

Treesearch

David F. Olson; Stephen G. Boyce

1971-01-01

Acorn production is extremely variable and unpredictable. Flowering is copious, but many climatic factors influence acorn development from initiation of flowers to acorn maturity. Acorns are consumed by birds, animals, insects, and microorganisms. The establishment of seedlings is more closely related to favorable site factors than to size of crops. A majority of oaks...

The influence of shade on northern red oak seedlings growth and carbon balance

Treesearch

Jennifer L. Jennings

1995-01-01

One management problem of the Southern Appalachian mixed hardwood forest is the lack of development of northern red oak (Quercus rubra L.) seedlings on high quality sites. Regeneration of red oak is not the problem. Following the removal of a stand, a combination of new seedlings, advanced reproduction and stump sprouts ensure red oak's initial...

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...

Genetic linkage map construction and QTL mapping of seedling height, basal diameter and crown width of Taxodium 'Zhongshanshan 302' × T. mucronatum.

PubMed

Wang, Ziyang; Cheng, Yanli; Yin, Yunlong; Yu, Chaoguang; Yang, Ying; Shi, Qin; Hao, Ziyuan; Li, Huogen

2016-01-01

Taxodium is a genus renowned for its fast growth, good form and tolerance of flooding, salt, alkalinity, disease and strong winds. In this study, a genetic linkage map was constructed using sequence-related amplified polymorphism (SRAP) and simple sequence repeat (SSR) markers based on an F1 population containing 148 individuals generated from a cross between T. 'Zhongshanshan 302' and T. mucronatum. The map has a total length of 976.5 cM, with a mean distance of 7.0 cM between markers, and contains 34 linkage groups with 179 markers (171 SRAPs and 8 SSRs). Quantitative trait loci (QTLs) affecting growth traits, such as seedling height, basal diameter and crown width, were detected based on the constructed linkage map. Four significant QTLs were identified, three of which, namely qtSH-1 for seedling height, qtBD-1 for basal diameter and qtCW-1 for crown width, were located at 2.659 cM of LG7 with logarithm odds values of 3.72, 3.49 and 3.93, respectively, and explained 24.9, 27.0 and 21.7 % of the total variation of the three grown traits, respectively. Another QTL for crown width (qtCW-2) was detected at 1.0 cM on LG13, with a logarithm of odds value of 3.15, and explained 31.7 % of the total variation of crown width. This is the first report on the construction of a genetic linkage map and QTL analysis in Taxodium, laying the groundwork for the construction of a high-density genetic map and QTL mapping in the genus Taxodium.

Root-associated ectomycorrhizal fungi shared by various boreal forest seedlings naturally regenerating after a fire in interior alaska and correlation of different fungi with host growth responses.

PubMed

Bent, Elizabeth; Kiekel, Preston; Brenton, Rebecca; Taylor, D Lee

2011-05-01

The role of common mycorrhizal networks (CMNs) in postfire boreal forest successional trajectories is unknown. We investigated this issue by sampling a 50-m by 40-m area of naturally regenerating black spruce (Picea mariana), trembling aspen (Populus tremuloides), and paper birch (Betula papyrifera) seedlings at various distances from alder (Alnus viridis subsp. crispa), a nitrogen-fixing shrub, 5 years after wildfire in an Alaskan interior boreal forest. Shoot biomasses and stem diameters of 4-year-old seedlings were recorded, and the fungal community associated with ectomycorrhizal (ECM) root tips from each seedling was profiled using molecular techniques. We found distinct assemblages of fungi associated with alder compared with those associated with the other tree species, making the formation of CMNs between them unlikely. However, among the spruce, aspen, and birch seedlings, there were many shared fungi (including members of the Pezoloma ericae [Hymenoscyphus ericae] species aggregate, Thelephora terrestris, and Russula spp.), raising the possibility that these regenerating seedlings may form interspecies CMNs. Distance between samples did not influence how similar ECM root tip-associated fungal communities were, and of the fungal groups identified, only one of them was more likely to be shared between seedlings that were closer together, suggesting that the majority of fungi surveyed did not have a clumped distribution across the small scale of this study. The presence of some fungal ribotypes was associated with larger or smaller seedlings, suggesting that these fungi may play a role in the promotion or inhibition of seedling growth. The fungal ribotypes associated with larger seedlings were different between spruce, aspen, and birch, suggesting differential impacts of some host-fungus combinations. One may speculate that wildfire-induced shifts in a given soil fungal community could result in variation in the growth response of different plant species after fire and a shift in regenerating vegetation.

Density-dependent dynamics of a dominant rain forest tree change with juvenile stage and time of masting.

PubMed

Norghauer, Julian M; Newbery, David M

2016-05-01

Although negative density dependence (NDD) can facilitate tree species coexistence in forests, the underlying mechanisms can differ, and rarely are the dynamics of seedlings and saplings studied together. Herein we present and discuss a novel mechanism based on our investigation of NDD predictions for the large, grove-forming ectomycorrhizal mast fruiting tree, Microberlinia bisulcata (Caesalpiniaceae), in an 82.5-ha plot at Korup, Cameroon. We tested whether juvenile density, size, growth and survival decreases with increasing conspecific adult basal area for 3245 'new' seedlings and 540 'old' seedlings (< 75-cm tall) during an approximately 4-year study period (2008-2012) and for 234 'saplings' (≥ 75-cm tall) during an approximately 6-year study period (2008-2014). We found that the respective densities of new seedlings, old seedlings and saplings were positively, not and negatively related to increasing BA. Maximum leaf numbers and heights of old seedlings were negatively correlated with increasing basal areas, as were sapling heights and stem diameters. Whereas survivorship of new seedlings decreased by more than one-half with increasing basal area over its range in 2010-2012, that of old seedlings decreased by almost two-thirds, but only in 2008-2010, and was generally unrelated to conspecific seedling density. In 2010-2012 relative growth rates in new seedlings' heights decreased with increasing basal area, as well as with increasing seedling density, together with increasing leaf numbers, whereas old seedlings' growth was unrelated to either conspecific density or basal area. Saplings of below-average height had reduced survivorship with increasing basal area (probability decreasing from approx. 0.4 to 0.05 over the basal area range tested), but only sapling growth in terms of leaf numbers decreased with increasing basal area. These static and dynamic results indicate that NDD is operating within this system, possibly stabilizing the M. bisulcata population. However, these NDD patterns are unlikely to be caused by symmetric competition or by consumers. Instead, an alternative mechanism for conspecific adult-juvenile negative feedback is proposed, one which involves the interaction between tree phenology and ectomycorrhizal linkages.

Influence of sewage sludge, as a substrate, in the plasticity of functional characteristics of plants.

PubMed

da Silva, Vicente Elício Porfiro Sales Gonçalves; Buarque, Patrícia Marques Carneiro; Ferreira, Wanessa Nepomuceno; Buarque, Hugo Leonardo de Brito; Silva, Maria Amanda Menezes

2018-04-24

This work aimed to evaluate the effect of sewage sludge application as fertilizer on the plasticity of functional characteristics of species commonly found in the Caatinga. The research was developed in the nursery of the Federal Institute of Education, Science and Technology of Ceará (IFCE), Quixadá campus, located in northeastern Brazil. Three treatments were applied: raw sludge, sanitized sludge, and no manipulation. In each treatment, five species were planted, each with five individuals, totaling 75 individuals, which were tagged, and 4 months after germination, they were destroyed to obtain dry matter content (TMSF) from leaf, stem (TMSC), fine root (TMSRF), and thick root (TMSRG); leaf area; height and diameter of the seedling; and length above and below the ground. The sanitized sludge was responsible for giving higher values for leaf area, height of the seedlings, and diameter and length of stem and root. However, the dry matter content of the fine roots was higher in the treatment without manipulation. At the community level, as TMSRG increased, TMSC also increased, the same occurred between TMSRG and TMSRF, TMSC and TMSRF, and stem length and leaf area. In the treatment without manipulation, there was a positive correlation between leaf area, height and plant diameter, and negative correlation between root length and plant diameter. Thus, it can be concluded that the use of sanitized sludge is a good tool to increase the availability of soil resources, conferring to individuals' greater dry matter content, greater leaf area, and higher height and diameter above the ground.

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.

Bacillus methylotrophicus Strain NKG-1, Isolated from Changbai Mountain, China, Has Potential Applications as a Biofertilizer or Biocontrol Agent.

PubMed

Ge, Beibei; Liu, Binghua; Nwet, Thinn Thinn; Zhao, Wenjun; Shi, Liming; Zhang, Kecheng

2016-01-01

Chemical pesticides are widely used in agriculture, which endangers both environmental health and food safety. Biocontrol is an environmentally-friendly and cost-effective green technique in environmental protection and agricultural production; it generally uses selected bioresources, including beneficial microorganisms. We isolated a novel bacterial strain (NKG-1) from the rare dormant volcanic soils of Changbai Mountain in China's Jilin Province. The strain was identified as Bacillus methylotrophicus using morphological, biochemical, physiological, and phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi on solid media. A greenhouse experiment showed that application of NKG-1 fermentation broth prior to inoculation of Botrytis cinerea, the cause of gray tomato mold, inhibited growth of the mold by 60%. Furthermore, application of a 100× dilution of NKG-1 fermentation broth to tomato seedlings yielded a significant increase in seedling fresh weight (27.4%), seedling length (12.5%), and root length (57.7%) compared to the control. When the same dosage was applied in the field, we observed increases in tomato plant height (14.7%), stem diameter (12.7%), crown width (16.3%), and maximum fruit diameter (11.5%). These results suggest that NKG-1 has potential commercial application as a biofertilizer or biocontrol agent.

Bacillus methylotrophicus Strain NKG-1, Isolated from Changbai Mountain, China, Has Potential Applications as a Biofertilizer or Biocontrol Agent

PubMed Central

Ge, Beibei; Liu, Binghua; Nwet, Thinn Thinn; Zhao, Wenjun; Shi, Liming; Zhang, Kecheng

2016-01-01

Chemical pesticides are widely used in agriculture, which endangers both environmental health and food safety. Biocontrol is an environmentally-friendly and cost-effective green technique in environmental protection and agricultural production; it generally uses selected bioresources, including beneficial microorganisms. We isolated a novel bacterial strain (NKG-1) from the rare dormant volcanic soils of Changbai Mountain in China’s Jilin Province. The strain was identified as Bacillus methylotrophicus using morphological, biochemical, physiological, and phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi on solid media. A greenhouse experiment showed that application of NKG-1 fermentation broth prior to inoculation of Botrytis cinerea, the cause of gray tomato mold, inhibited growth of the mold by 60%. Furthermore, application of a 100× dilution of NKG-1 fermentation broth to tomato seedlings yielded a significant increase in seedling fresh weight (27.4%), seedling length (12.5%), and root length (57.7%) compared to the control. When the same dosage was applied in the field, we observed increases in tomato plant height (14.7%), stem diameter (12.7%), crown width (16.3%), and maximum fruit diameter (11.5%). These results suggest that NKG-1 has potential commercial application as a biofertilizer or biocontrol agent. PMID:27832162

Photoacoustic technique applied to ethylene emission in passion fruit seedlings: An experimental approach

NASA Astrophysics Data System (ADS)

Pereira, T.; Baptista-Filho, M.; Corrêa, S. F.; de Oliveira, J. G.; da Silva, M. G.; Vargas, H.

2005-06-01

It is well known that plants respond to mechanical perturbation, such as swaying in the wind, touching or brushing, by a reduction in stem length and an increase in stem diameter. Brushing provides a tactile or thigmic stimulation of the plant growing points and undergo physiological and developmental changes that increase stress tolerance. One of the main hormones released by brushing plants is thought to be ethylene, a plant hormone difficult to trace and monitor because it is a gas. The emission rate of ethylene was monitored using a photoacoustic spectrometer based on the infrared absorption of the line 10P12 and 10P14 of CO2 LASER. In response to the brushing treatment, seedlings of passion fruit (Passiflora edulis L.) showed a increase in the ethylene emission. The aim of this work was to investigate the effect of brushing on the ethylene emission rate of passion fruit seedlings.

Stem demography and postfire recruitment of a resprouting serotinous conifer

USGS Publications Warehouse

Keeley, Jon E.; Keeley, Melanie B.; Bond, William J.

1999-01-01

The contribution of resprouts and seedling recruitment to post-fire regeneration of the South African fynbos conifer Widdringtonia nodiflora was compared eight months after wildfires in 1990. Stems on all trees were killed by fire but resprouting success was > 90 % at all but one site. A demographic study of burned skeletons revealed that prior to these fires, nearly all plants were multi-stemmed (4–9 stems/plant) and multi-aged, indicating continuous sprout production between fires. All stems were killed by these 1990 fires and at most sites > 90 % of the stems were burned to ground level. All diameter stems were susceptible to such incineration as, at most sites, there was no difference in average diameter of stems burned to ground level and those left standing. Individual genets usually had all ramets incinerated to ground level or all ramets charred, but intact, suggesting certain micro-sites burned hotter, whereas other sites were somewhat protected. Although not true of the 1990 fires, there was evidence that occasionallyWiddring-tonia stems may survive fire. At one site, four of the 16 plants sampled had a burned stem twice as old as the oldest burned stem on the other 12 plants at the site, suggesting some stems had survived the previous fire (ca. 1970) and this conclusion was supported by fire-scars on these four stems that dated to ca. 1970. Based on the highly significant correlation between stem diameter and cone density left standing after the 1990 fires, we calculated that for most sites > 80 % of the initial cone crop was incinerated by fire. This is important because we observed a strong relationship between size of the canopy cone crop surviving fire and post-fire seedling recruitment. Under these conditions we hypothesize that sprouting confers a selective advantage to genets when fires cause heavy losses of seed. The infrequent occurrence of sprouting in theCupressaceae suggests the hypothesis that resprouting is an apomorphic or derived trait inWiddringtonia. Data from this study suggests resprouting provides a selective advantage under severe fynbos fires, which are not only 'stand-replacing fires,’but also are intense enough to incinerate cone-bearing stems.

Stem demography and post-fire recruitment of a resprouting serotinous conifer

USGS Publications Warehouse

Keeley, J.E.; Keeley, M.B.; Bond, W.J.

1999-01-01

The contribution of resprouts and seedling recruitment to post-fire regeneration of the South African fynbos conifer Widdringtonia nodiflora was compared eight months after wildfires in 1990. Stems on all trees were killed by fire but resprouting success was > 90 % at all but one site. A demographic study of burned skeletons revealed that prior to these fires, nearly all plants were multi-stemmed (4 - 9 stems/plant) and multi-aged, indicating continuous sprout production between fires. All stems were killed by these 1990 fires and at most sites > 90 % of the stems were burned to ground level. All diameter stems were susceptible to such incineration as, at most sites, there was no difference in average diameter of stems burned to ground level and those left standing. Individual genets usually had all ramets incinerated to ground level or all ramets charred, but intact, suggesting certain micro-sites burned hotter, whereas other sites were somewhat protected. Although not true of the 1990 fires, there was evidence that occasionally Widdringtonia stems may survive fire. At one site, four of the 16 plants sampled had a burned stem twice as old as the oldest burned stem on the other 12 plants at the site, suggesting some stems had survived the previous fire (ca. 1970) and this conclusion was supported by fire-scars on these four stems that dated to ca. 1970. Based on the highly significant correlation between stem diameter and cone density left standing after the 1990 fries, we calculated that for most sites > 80 % of the initial cone crop was incinerated by fire. This is important because we observed a strong relationship between size of the canopy cone crop surviving fire and post-fire seedling recruitment. Under these conditions we hypothesize that sprouting confers a selective advantage to genets when fires cause heavy losses of seed. The infrequent occurrence of sprouting in the Cupressaceae suggests the hypothesis that resprouting is an apomorphic or derived trait in Widdringtonia. Data from this study suggests resprouting provides a selective advantage under severe fynbos fires, which are not only 'stand-replacing fires,' but also are intense enough to incinerate cone-bearing stems.

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.

[Screening and identification of endophytic fungi with growth promoting effect on Dendrobium officinale].

PubMed

Hou, Xiao-qiang; Guo, Shun-xing

2014-09-01

The endophytic fungi with plant growth promoting effects were screened by co-culture of each endophytic fungus and seedlings of Dendrobium officinale. Anatomical features of the inoculated roots were studied by paraffin sectioning. Morphological characteristics and rDNA ITS1-5. 8S-ITS2 sequences were applied for the taxonomy of endophytic fungi. The results showed that 8 strains inoculated to D. officinale seedlings greatly enhanced plant height, stem diameter, new roots number and biomass. According to the anatomical features of the inoculated roots, each fungus could infect the velamina of seedlings. The hyphae or pelotons were existed in the exodermis passage cells and cortex cells. The effective fungi could not infect the endodermis and vascular bundle sheath, but which was exception for other fungi with harmful to seedlings. Combined with classic morphologic classification, 2 effective strains were identified which were subjected to Pestalotiopsis and Eurotium. Six species of fungi without conidiophore belonged to Pyrenochaeta, Coprinellus, Pholiota, Alternaria, Helotiales, which were identified by sequencing the PCR-amplified rDNA ITS1-5. 8S-ITS2 regions. The co-culture technology of effective endophytic fungi and plant can apply to cultivate the seedlings of D. officinale. It is feasible to shorten growth cycle of D. officinale and increase the resource of Chinese herbs.

The effects of gap size and disturbance type on invasion of wet pine savanna by cogongrass, Imperata cylindrica (Poaceae)

USGS Publications Warehouse

King, S.E.; Grace, J.B.

2000-01-01

Cogongrass is a nonindigenous species perceived to threaten native communities of the southeastern United States through modification of species composition and alteration of community processes. To examine how gap size and disturbance type influence the invasion of wet pine savannas by cogongrass, we performed three field experiments to evaluate the response of cogongrass seeds and transplanted seedlings to four different gap sizes, four types of site disturbance, and recent burning of savanna vegetation. Cogongrass germinated, survived, and grew in all gap sizes, from 0 to 100 cm in diameter. Similarly, disturbance type had no effect on germination or seedling and transplant survival. Tilling, however, significantly enhanced transplanted seedling growth, resulting in a tenfold increase in biomass over the other disturbance types. Seedling survival to 1 and 2 mo was greater in burned savanna than unburned savanna, although transplant survival and growth were not affected by burning. Results of this study suggest that cogongrass can germinate, survive, and grow in wet pine savanna communities regardless of gap size or type of disturbance, including burning. Burning of savanna vegetation may enhance establishment by improving early seedling survival, and soil disturbance can facilitate invasion of cogongrass by enhancing plant growth.

The effects of gap size and disturbance type on invasion of wet pine savanna by cogongrass, Imperata cylindrica (Poaceae).

PubMed

King, S E; Grace, J B

2000-09-01

Cogongrass is a nonindigenous species perceived to threaten native communities of the southeastern United States through modification of species composition and alteration of community processes. To examine how gap size and disturbance type influence the invasion of wet pine savannas by cogongrass, we performed three field experiments to evaluate the response of cogongrass seeds and transplanted seedlings to four different gap sizes, four types of site disturbance, and recent burning of savanna vegetation. Cogongrass germinated, survived, and grew in all gap sizes, from 0 to 100 cm in diameter. Similarly, disturbance type had no effect on germination or seedling and transplant survival. Tilling, however, significantly enhanced transplanted seedling growth, resulting in a tenfold increase in biomass over the other disturbance types. Seedling survival to 1 and 2 mo was greater in burned savanna than unburned savanna, although transplant survival and growth were not affected by burning. Results of this study suggest that cogongrass can germinate, survive, and grow in wet pine savanna communities regardless of gap size or type of disturbance, including burning. Burning of savanna vegetation may enhance establishment by improving early seedling survival, and soil disturbance can facilitate invasion of cogongrass by enhancing plant growth.

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

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.

The short-term effects of fertilization on loblolly pine photosynthesis and biomass

Treesearch

Nathan King; John Seiler; Thomas R. Fox; Kurt Johnsen

2006-01-01

The physiological processes in loblolly pine leading to enhanced growth in response to fertilization have not been clearly established. We tracked net photosynthesis (Pn), height, basal diameter, and volume changes in loblolly pine seedlings in response to fertilization during the entire 2004 growing season. Pn measurements...

Restoring southern Ontario forests by managing succession in conifer plantations

Treesearch

William C. Parker; Ken A. Elliott; Daniel C. Dey; Eric Boysen

2008-01-01

Thinning and underplanting of conifer plantations to promote natural succession in southern Ontario's forests for restoration purposes was examined in a young red pine (Pinus resinosa Ait.) plantation. Eleven years after application of five thinning treatments, seedling diameter, height, and stem volume of planted white ash (Fraxinus...

Effect Of Seedling Size And First-Order Lateral Roots On Early Development Of Northern Red Oak On A Mesic Site: Eleventh-Year Results

Treesearch

Paul P. Kormanik; Shi-Jean S. Sung; Donald Kass; Stanley J. Zarnoch

2002-01-01

Abstract - The effect of initial first-order lateral root (FOLR) groupings of northern red oak (Quercus rubra) seedlings on a high quality mesic site was followed for eleven years on a shelterwood and a clearcut area. The initial FOLR number groups were empirically determined as low (0 to 6) medium (7 to 12) and high (12). The...

Nucleolus in clinostat-grown plants

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

Shen-Miller, J.; Dannenhoffer, J.; Hinchman, R.

1991-05-01

The clinostat is an apparatus that is used to mimic zero gravity in studies of plant growth in the absence of gravitropic response. Clinostat-grown tissue cultures of carrot exhibit significant increases both in the number of nuclei containing more than one nucleolus and in nucleolar volume. Oat seedlings germinated and grown on clinostats exhibit a decreased rate of shoot elongation, increased tissue sensitivity to applied auxin, and an increased response to gravitropic stimulation. Clinostat treatment clearly affects plant metabolism. The nucleolus is the region in the nucleus where ribosome synthesis and assembly take place. The 18S, 5.8S, and 25S ribosomalmore » genes, in tandem units, are located in the nucleolus. Ribosomes orchestrate the production of all proteins that are necessary for the maintenance of cell growth, development, and survival. A full study of the effects of nullification of gravitropism, by clinostat rotation, on nucleolar development in barley has been initiated. The authors study developmental changes of nucleolar number and diameter in clinostat-grown root tissues. Preliminary results show that barley roots exhibit changes in nucleolar number and diameter. Growth rates of barley root and shoot also appear to be reduced, in measurements of both length and weight.« less

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.

Mechanisms of Douglas-fir resistance to western spruce budworm defoliation: bud burst phenology, photosynthetic compensation and growth rate.

PubMed

Chen, Z; Kolb, T E; Clancy, K M

2001-10-01

We compared growth rates among mature interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) trees showing resistance or susceptibility to defoliation caused by western spruce budworm (Choristoneura occidentalis Freeman), and among clones and half-sib seedling progeny of these trees in a greenhouse. We also investigated bud burst phenology and photosynthetic responses of clones to budworm defoliation in greenhouse experiments. Resistant mature trees had a higher radial growth rate than susceptible trees, especially during periods of budworm defoliation. Clones from resistant trees grew larger crowns than clones from susceptible trees, whereas stem base diameter at the ground line and height did not differ. Half-sib seedling progeny from resistant trees had larger stem diameter, height, and total biomass than progeny from susceptible trees. Mean 5-year radial growth increment of mature trees was more strongly correlated with growth of seedlings than with growth of clones. Clones from resistant trees had later bud burst than clones from susceptible trees, and budworm defoliation of clones depended on the degree of synchrony between bud burst phenology and budworm larval feeding. Clones of resistant and susceptible mature trees showed similar responses of net photosynthetic rate to 2 years of budworm defoliation. We conclude that phenotypic differences in crown condition of Douglas-fir trees following western spruce budworm defoliation are influenced by tree genotype and that high growth rate and late bud burst phenology promote tree resistance to budworm defoliation.

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.

Sensitivity of salad greens (Lactuca sativa L. and Eruca sativa Mill.) exposed to crude extracts of toxic and non-toxic cyanobacteria.

PubMed

Bittencourt-Oliveira, M C; Hereman, T C; Macedo-Silva, I; Cordeiro-Araújo, M K; Sasaki, F F C; Dias, C T S

2015-05-01

We evaluated the effect of crude extracts of the microcystin-producing (MC+) cyanobacteria Microcystis aeruginosa on seed germination and initial development of lettuce and arugula, at concentrations between 0.5 μg.L(-1) and 100 μg.L(-1) of MC-LR equivalent, and compared it to crude extracts of the same species without the toxin (MC-). Crude extracts of the cyanobacteria with MC (+) and without MC (-) caused different effects on seed germination and initial development of the salad green seedlings, lettuce being more sensitive to both extracts when compared to arugula. Crude extracts of M. aeruginosa (MC+) caused more evident effects on seed germination and initial development of both species of salad greens than MC-. Concentrations of 75 μg.L(-1) and 100 μg.L(-1) of MC-LR equivalent induced a greater occurrence of abnormal seedlings in lettuce, due to necrosis of the radicle and shortening of this organ in normal seedlings, as well as the reduction in total chlorophyll content and increase in the activity of the antioxidant enzyme peroxidase (POD). The MC- extract caused no harmful effects to seed germination and initial development of seedlings of arugula. However, in lettuce, it caused elevation of POD enzyme activity, decrease in seed germination at concentrations of 75 μg.L(-1) (MC-75) and 100 μg.L(-1) (MC-100), and shortening of the radicle length, suggesting that other compounds present in the cyanobacteria extracts contributed to this result. Crude extracts of M. aeruginosa (MC-) may contain other compounds, besides the cyanotoxins, capable of causing inhibitory or stimulatory effects on seed germination and initial development of salad green seedlings. Arugula was more sensitive to the crude extracts of M. aeruginosa (MC+) and (MC-) and to other possible compounds produced by the cyanobacteria.

Terpenoid Variations within and among Half-Sibling Avocado Trees, Persea americana Mill. (Lauraceae)

PubMed Central

Niogret, Jerome; Epsky, Nancy D.; Schnell, Raymond J.; Boza, Edward J.; Kendra, Paul E.; Heath, Robert R.

2013-01-01

Chemical analyses were conducted to determine the qualitative and quantitative differences in monoterpenes and sesquiterpenes in plant material from avocado trees, Persea americana Mill. (Lauraceae). The initial study analyzed plant material sampled from the trunk to the leaves through different branch diameters to quantify proximo-distal spatial differences within a tree. All trees were seedlings initiated from a single maternal tree. Two-way analysis of variance was conducted on 34 chemicals that comprised at least 3% of the total chemical content of at least one tree and/or location within a tree. There were significant interactions between genotype and location sampled for most chemicals. Parentage analysis using microsatellite molecular markers (SSR's) determined that the four trees had three fathers and that they represented two full-siblings and two half-sibling trees. Descriptive discriminant analysis found that both genotype and location within a tree could be separated based on chemical content, and that the chemical content from full-siblings tended to be more similar than chemical content from half-siblings. To further explore the relationship between genetic background and chemical content, samples were analyzed from leaf material from 20 trees that included two sets of full-sibling seedling trees, the maternal tree and the surviving paternal tree. Descriptive discriminant analysis found good separation between the two full-sibling groups, and that the separation was associated with chemistry of the parental trees. Six groups of chemicals were identified that explained the variation among the trees. We discuss the results in relation to the discrimination process used by wood-boring insects for site-selection on host trees, for tree selection among potential host trees, and the potential use of terpenoid chemical content in chemotaxonomy of avocado trees. PMID:24039994

Terpenoid variations within and among half-sibling avocado trees, Persea americana Mill. (Lauraceae).

PubMed

Niogret, Jerome; Epsky, Nancy D; Schnell, Raymond J; Boza, Edward J; Kendra, Paul E; Heath, Robert R

2013-01-01

Chemical analyses were conducted to determine the qualitative and quantitative differences in monoterpenes and sesquiterpenes in plant material from avocado trees, Persea americana Mill. (Lauraceae). The initial study analyzed plant material sampled from the trunk to the leaves through different branch diameters to quantify proximo-distal spatial differences within a tree. All trees were seedlings initiated from a single maternal tree. Two-way analysis of variance was conducted on 34 chemicals that comprised at least 3% of the total chemical content of at least one tree and/or location within a tree. There were significant interactions between genotype and location sampled for most chemicals. Parentage analysis using microsatellite molecular markers (SSR's) determined that the four trees had three fathers and that they represented two full-siblings and two half-sibling trees. Descriptive discriminant analysis found that both genotype and location within a tree could be separated based on chemical content, and that the chemical content from full-siblings tended to be more similar than chemical content from half-siblings. To further explore the relationship between genetic background and chemical content, samples were analyzed from leaf material from 20 trees that included two sets of full-sibling seedling trees, the maternal tree and the surviving paternal tree. Descriptive discriminant analysis found good separation between the two full-sibling groups, and that the separation was associated with chemistry of the parental trees. Six groups of chemicals were identified that explained the variation among the trees. We discuss the results in relation to the discrimination process used by wood-boring insects for site-selection on host trees, for tree selection among potential host trees, and the potential use of terpenoid chemical content in chemotaxonomy of avocado trees.

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.

Seed size variation in the palm Euterpe edulis and the effects of seed predators on germination and seedling survival

NASA Astrophysics Data System (ADS)

Pizo, Marco A.; Von Allmen, Christiane; Morellato, L. Patricia C.

2006-05-01

Intraspecific variation in seed size is common in wild plant populations and has important consequences for the reproductive success of individual plants. Multiple, often conflicting evolutionary forces mediated by biotic as well as abiotic agents may maintain such a variation. In this paper we assessed seed size variation in a population of the threatened, commercially important palm Euterpe edulis in southeast Brazil. We investigated (i) how this variation affects the probability of attack by vertebrate and invertebrate post-dispersal seed predators, and (ii) if seed size influences the outcome of seeds damaged by beetles in terms of seed germination and early survival of seedlings. Euterpe edulis seeds varied in diameter from 8.3 to 14.1 mm. Neither insects nor rodents selected the seeds they preyed upon based on seed size. Seed germination and total, shoot and root biomasses of one-year seedlings were significantly and positively affected by seed size. Root biomass and seedling survival were negatively affected by seed damage caused by a scolytid beetle ( Coccotrypes palmarum) whose adults bore into seeds to consume part of the endosperm, but do not oviposit on them. Seed size had a marginally significant effect on seedling survival. Therefore, if any advantage is accrued by E. edulis individuals producing large seeds, this is because of greater seed germination success and seedling vigor. If this is so, even a relatively narrow range of variation in seed size as observed in the E. edulis population studied may translate into differential success of individual plants.

Edaphic history over seedling characters predicts integration and plasticity of integration across geologically variable populations of Arabidopsis thaliana.

PubMed

Cousins, Elsa A; Murren, Courtney J

2017-12-01

Studies on phenotypic plasticity and plasticity of integration have uncovered functionally linked modules of aboveground traits and seedlings of Arabidopsis thaliana , but we lack details about belowground variation in adult plants. Functional modules can be comprised of additional suites of traits that respond to environmental variation. We assessed whether shoot and root responses to nutrient environments in adult A. thaliana were predictable from seedling traits or population-specific geologic soil characteristics at the site of origin. We compared 17 natural accessions from across the native range of A. thaliana using 14-day-old seedlings grown on agar or sand and plants grown to maturity across nutrient treatments in sand. We measured aboveground size, reproduction, timing traits, root length, and root diameter. Edaphic characteristics were obtained from a global-scale dataset and related to field data. We detected significant among-population variation in root traits of seedlings and adults and in plasticity in aboveground and belowground traits of adult plants. Phenotypic integration of roots and shoots varied by population and environment. Relative integration was greater in roots than in shoots, and integration was predicted by edaphic soil history, particularly organic carbon content, whereas seedling traits did not predict later ontogenetic stages. Soil environment of origin has significant effects on phenotypic plasticity in response to nutrients, and on phenotypic integration of root modules and shoot modules. Root traits varied among populations in reproductively mature individuals, indicating potential for adaptive and integrated functional responses of root systems in annuals. © 2017 Botanical Society of America.

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 exogenous spermidine on lipid peroxidation and membrane proton pump activity of cucumber seedling leaves under high temperature stress].

PubMed

Tian, Jing; Guo, Shi-Rong; Sun, Jin; Wang, Li-Ping; Yang, Yan-Juan; Li, Bin

2011-12-01

Taking a relatively heat-resistant cucumber (Cucumis sativus) cultivar 'Jinchun No. 4' as test material, a sand culture experiment was conducted in growth chamber to investigate the effects of foliar spraying spermidine (Spd) on the lipid peroxidation, membrane proton pump activity, and corresponding gene expression of cucumber seedling leaves under high temperature stress. Compared with the control, foliar spraying Spd increased the plant height, stem diameter, dry and fresh mass, and leaf area significantly, and inhibited the increase of leaf relative conductivity, malondialdehyde (MDA) content, and lipoxygenase (LOX) activity effectively. Foliar spraying Spd also helped to the increase of leaf plasma membrane- and tonoplast H(+)-ATPase activity, but no significant difference was observed in the gene expression levels. These results suggested that exogenous Spd could significantly decrease the leaf lipid peroxidation and increase the proton pump activity, and thus, stabilize the leaf membrane structure and function, alleviate the damage induced by high temperature stress, and enhance the heat tolerance of cucumber seedlings.

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

Influence of planting stocks on the survival and growth of Nuttall and cherrybark oak planted on lands damaged by Hurricane Katrina

Treesearch

Derek K. Alkire; James C. Rainer; Andrew B. Self; Andrew W. Ezell; Andrew J. Londo; Emily B. Schultz

2013-01-01

Bare-root, container, and root production method (RPMTM) seedlings of Nuttall oak (Quercus texana Buckley) and cherrybark oak (Q. pagoda Ell.) were planted on lands damaged by Hurricane Katrina in southern Mississippi to compare the height growth, groundline diameter (GLD) growth, and survival of the...

Assessing the potential for biomass energy development in South Carolina

Treesearch

Roger C. Conner; Tim O. Adams; Tony G. Johnson

2009-01-01

An assessment of the potential for developing a sustainable biomass energy industry in South Carolina was conducted. Biomass as defined by Forest Inventory and Analysis is the aboveground dry weight of wood in the bole and limbs of live trees ≥1-inch diameter at breast height, and excludes tree foliage, seedlings, and understory...

Hardwood Regeneration on the Loessial Hills After Harvesting For Uneven-Aged Management

Treesearch

J.C.G. Goelz; J.S. Meadows

1995-01-01

In 1991, study plots were harvested to four different residual diameter distributions. Generally, for all specks, the more extreme overstory removals promoted regeneration establishment while the trestment with the least overstory removal tended to provide less regeneration than the uncut controk For oak spscies, most of the seedlings present in 1993 were those...

Treatment duration and time since disturbance affect vegetation development in a young ponderosa pine plantation

Treesearch

Gary O. Fiddler; Philip M. McDonald

1999-01-01

The effect of early and delayed release treatments (designated as "Treat first 3 years" and "Treat second 3 years," respectively) on diameter, height, and foliar cover of ponderosa pine seedlings, and density, foliar cover, and height of competing vegetation was evaluated in a young northern California plantation. Manual grubbing created vegetation...

Managing succession in conifer plantations: converting young red pine (Pinus resinosa Ait.) plantations to native forest types by thinning and underplantiing

Treesearch

William C. Parker; Ken A. Elliott; Daniel C. Dey; Eric Boysen; Steven G. Newmaster

2001-01-01

The effects of thinning on growth and survival of white pine (Pinus strobus L.), white ash (Fraxinus americana L.), and red oak (Quercus rubra L.), and understory plant diversity were examined in a young red pine (Pinus resinosa Ait.) plantation. Five years after thinning, seedling diameter,...

Comparing Planting Tools for Container Longleaf Pine

Treesearch

Daniel J. Leduc; James D. Haywood; Shi-Jean Susana Sung

2011-01-01

We examined if compressing the soil to make a planting hole with a custom-built, solid round dibble versus coring the soil with a commercially available tube dibble influenced container-grown longleaf pine seedling development differently. Seven teen months after planting, the planting tool did not significantly affect root collar diameter, shoot or root mass, root-to-...

The target plant concept-a history and brief overview

Treesearch

Thomas D. Landis

2011-01-01

The target plant concept originated with morphological classification of conifer nursery stock in the 1930s, and the concept was enhanced through physiological research and seedling testing towards the end of the century. Morphological grading standards such as shoot height, stem diameter, and root mass are the most common use of the target plant concept, and some...

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)'.

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...

Soil compaction and initial height growth of planted ponderosa pine.

Treesearch

P. H. Cochran; Terry. Brock

1985-01-01

Early height growth of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedlings planted in clearcuts in central Oregon was negatively correlated with increasing soil bulk density. Change in bulk density accounted for less than half the total variation in height growth. Although many other factors affect the development of seedlings, compaction...

Interactive effects of CO2 and O3 on a ponderosa pine plant/litter/soil mesocosm.

PubMed

Olszyk, D M; Johnson, M G; Phillips, D L; Seidler, R J; Tingey, D T; Watrud, L S

2001-01-01

To study individual and combined impacts of two important atmospheric trace gases, CO2 and O3, on C and N cycling in forest ecosystems; a multi-year experiment using a small-scale ponderosa pine (Pinus ponderosa Laws.) seedling/soil/litter system was initiated in April 1998. The experiment was conducted in outdoor, sun-lit chambers where aboveground and belowground ecological processes could be studied in detail. This paper describes the approach and methodology used, and presents preliminary data for the first two growing seasons. CO2 treatments were ambient and elevated (ambient + 280 ppm). O3 treatments were elevated (hourly averages to 159 ppb, cumulative exposure > 60 ppb O3, SUM 06 approximately 10.37 ppm h), and a low control level (nearly all hourly averages <40 ppb. SUM 06 approximately 0.07 ppm h). Significant (P < 0.05) individual and interactive effects occurred with elevated CO2 and elevated O3. Elevated CO2 increased needle-level net photosynthetic rates over both seasons. Following the first season, the highest photosynthetic rates were for trees which had previously received elevated O3 in addition to elevated CO2. Elevated CO2 increased seedling stem diameters, with the greatest increase at low O3. Elevated CO2 decreased current year needle % N in the summer. For 1-year-old needles measured in the fall there was a decrease in % N with elevated CO2 at low O3, but an increase in % N with elevated CO2 at elevated O3. Nitrogen fixation (measured by acetylene reduction) was low in ponderosa pine litter and there were no significant CO2 or O3 effects. Neither elevated CO2 nor elevated O3 affected standing root biomass or root length density. Elevated O3 decreased the % N in coarse-fine (1-2 mm diameter) but not in fine (< 1 mm diameter) roots. Both elevated CO2 and elevated O3 tended to increase the number of fungal colony forming units (CFUs) in the AC soil horizon, and elevated O3 tended to decrease bacterial CFUs in the C soil horizon. Thus, after two growing seasons we showed interactive effects of O3 and CO2 in combination, in addition to responses to CO2 or O3 alone for a ponderosa pine plant/litter/soil system.

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.

Cost Effectiveness of Natural Regeneration for Sustaining Production Continuity in Commercial Pine Plantations

Treesearch

T.R. Clason

2002-01-01

Reforestation is a key to production continuity in commercial pine plantations. Although natural and artificial regeneration methods have been used successfully for pine seedling establishment, it is seedling growth during early stage of plantation development that affects the financial potential of a pine plantation. A study was initiated to determine the effect of...

Initial response of underplanted yellow poplar and cherrybark oak seedlings to four levels of mechanical midstory removal

Treesearch

John M. Lhotka; Edward F. Loewenstein

2006-01-01

Midstory removal has been suggested as a possible enhancement strategy to develop seedling pools in stands lacking vigorous advanced oak (Quercus spp.) reproduction. However, for successful implementation, silviculturists must understand the differential growth responses of oak and its competitors to conditions created by midstory removal. To further...

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...

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

[Effects of light intensity on Quercus liaotungensis seed germination and seedling growth].

PubMed

Yan, Xing-fu; Wang, Jian-li; Zhou, Li-biao

2011-07-01

This paper studied the effects of different shading (55.4%, 18.9%, 5.5%, 2.2%, 0.5% , and 0.3% natural sunlight) on the seed germination and seedling growth of Quercus liaotungensis. The seed germination rate and germination index were the highest (72.5% and 0.22, respectively) at 55.4% natural sunlight, declined with decreasing light intensity, and were the lowest (42.5% and 0.11, respectively) at 0.3% natural sunlight. Strong light had definite delaying effect on the germination. The index of germination vigor increased with decreasing light intensity, being the maximum at 0.5% natural sunlight. The delay of seed germination under strong light could be the selective tradeoff on varied seed fates. Strong light benefited the basal stem diameter and root system growth and dry mass accumulation of Q. liaotunensis seedling, but resulted in the minimum seedlings height (6.06 cm). Greater morphological plasticity was observed for the seedlings under different shading, which lent support to the higher adaptability of the seedlings to light environment. For example, the specific leaf area, specific shoot length, specific root length, and chlorophyll b and total chlorophyll contents were the maximum at 0.5% natural sunlight, being 142.57 cm2 x g(-1), 156.86 cm x g(-1), 271.87 cm x g(-1), 0.07 g x cm(-2), and 0.24 g x cm(-2), respectively, and the minimum at 55.4% natural sunlight, being 44.89 cm2 x g(-1), 52.84 cm x g(-1), 101.98 cm x g(-1), 0.04 g x cm(-2), and 0.15 g x cm(-2), respectively. The variation of the root/shoot ratio of Q. liaotungensis seedlings under different shading could be the effects of the combination of light intensity and water availability.

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.

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.

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.

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.

Root-collar diameter and third-year survival of three bottomland hardwoods planted on former agricultural fields in the Lower Mississippi Alluvial Valley

Treesearch

Emile S. Gardiner; Douglass F. Jacobs; Ronald P. Overton; George Hernandez

2009-01-01

Athough the Lower Mississippi Alluvial Valley (LMAV) has experienced substantial afforestation of former agricultural fields during the past 2 decades, seedling standards that support satisfactory outplanting performance of bottomland hardwood tree species are not available. A series of experimental plantations, established on three afforestation sites in the LMAV,...

Cultural Treatments Influence Hardwood Growth and Foliar Nutrient Concentration on a Minor Stream Bottom Site

Treesearch

Harvey E. Kennedy

1985-01-01

Seedlings or cuttings of nine species of hardwoods were planted on a minor stream bottom (Aeric Fluvaquents) in southeast Arkansas and mowed or disked several times annually for 4 years. Disking to eliminate competition significantly increased heights and diameters of all, and survival of some, species. Soil nitrogen, organic matter, and pH were significantly lowered...

A 16-year evaluation of effects of ripping on shortleaf pine on a Missouri ozarks site

Treesearch

David Gwaze; Carl Hauser; Mark Johanson

2006-01-01

A shortleaf pine (Pinus echinata Mill.) ripping study was established by the Missouri Department of Conservation in March 1988 at the Logan Creek Conservation Area. The objective of the study was to evaluate the effects of ripping on survival, height, diameter, volume, crown spread, and free-to-grow status of planted shortleaf pine seedlings. Ripping...

Fertilizer and Mulch Improves Yellow-Poplar Growth on Exposed harsells Subsoils

Treesearch

John K. Francis

1977-01-01

Fertilizing and mulching of eroded Hartsells soil increased height and diameter of yellow-poplars. To see if chemical infertility of exposed Hartsells subsoils limits yellow-poplar growth and to test fertilizer and mulch as remedial agents, seedlings were planted on undisturbed soil, soil with the topsoil removed, and soil with the topsoil removed but mulched with leaf...

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.

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],...

The structure of the stem endodermis in etiolated pea seedlings

NASA Technical Reports Server (NTRS)

Sack, F. D.

1987-01-01

Differentiation of the endodermis was examined in third internodes of etiolated Pisum sativum L. cv. Alaska seedlings. The endodermis in young internodes contains large, sedimented amyloplasts; in older internodes, a casparian strip differentiates and the endodermis becomes depleted of starch except for the proximal region of the stem, which retains sedimented amyloplasts and remains graviresponsive. Sedimentation occurs in the hook but does not occur consistently until cells reach the base of the hook, where the axis becomes vertical, rapid cell elongation starts, and amyloplast diameter increases substantially. Contact between endoplasmic reticulum and amyloplasts was observed. Endoplasmic reticulum is not distributed polarly with respect to gravity. No symplastic or apoplastic blockages exist in the endodermis at the level of the stem where lateral gradients may be established during tropic curvature.

Does Jatropha curcas L. show resistance to drought in the Sahelian zone of West Africa? A case study from Burkina Faso

NASA Astrophysics Data System (ADS)

Bayen, P.; Sop, T. K.; Lykke, A. M.; Thiombiano, A.

2015-05-01

Land degradation is an environmental problem which weakens agro-sylvo-pastoral productivity in sub-Saharan Africa. The most common manifestation of land degradation is the appearance of denuded land. We carried out an experiment to test the effect of three soil and water conservation techniques on survival and growth of Jatropha curcas seedlings transplanted onto two completely denuded lands in the Sahelian and Sudanian zones of Burkina Faso. We implemented an experimental design with three replicates per restoration technique. A total of 174 seedlings were planted in each study site. The results showed that the soil water content varied according to the restoration technique used (df = 2; F = 53.21; p < 0.00) as well as according to study site (df = 1; F = 74.48; p < 0.00). Soil water content was significantly lower in the Sahel than in the Sudanian zone. Seedling survival rate varied significantly according to technique used (df = 2; F = 8.91; p = 0.000) and study site (df = 1; F = 9.74; p = 0.003). Survival rate, diameter and seedling height were highest at the Sudanian site. At the Sahelian site, all seedlings died 2 years after establishment. These results suggest that J. curcas is unsuited to denuded land in the Sahelian zone. Most of the plants died in the Sahel between April and May, which is the peak of the dry season; this may be an indication that J. curcas may not be as drought-resistant as suggested by the prolific literature which has reported on diverse claims surrounding this plant.

Does Jatropha curcas L. show resistance to drought in the Sahelian zone of West Africa? A case study from Burkina Faso

NASA Astrophysics Data System (ADS)

Bayen, P.; Sop, T. K.; Lykke, A. M.; Thiombiano, A.

2015-02-01

Land degradation is an environmental problem which weakens agro-silvo-pastoral productivity in Sub-Saharan Africa. The most common manifestation of land degradation is the appearance of denuded land. We carried out an experiment to test the effect of three soil and water conservation techniques on survival and growth of Jatropha curcas seedlings transplanted onto two completely denuded lands in the Sahelian and Sudanian zones of Burkina Faso. We implemented an experimental design with three replicates per restoration technique. A total of 174 seedlings were planted in each study site. The results showed that soil water content varied according to the restoration technique used (df = 2; F = 53.21; p < 0.00) as well as according to study site (df = 1; F = 74.48; p < 0.00). Soil water content was significantly lower in the Sahel than in the Sudanian zone. Seedling survival rate varied significantly according to technique used (df = 2; F = 8.91; p = 0.000) and study site (df = 1; F = 9.74; p = 0.003). Survival rate, diameter and seedling height were highest at the Sudanian site. At the Sahelian site, all seedlings died two years after establishment. These results suggest that Jatropha curcas is unsuited to denuded land in the Sahelian zone. Most of the plants died in the Sahel between April and May, which is the peak of the dry season; this may be an indication that Jatropha may not be as drought-resistant as suggested by the prolific literature which has reported on diverse claims surrounding this plant.

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.

Intraspecific Phenotypic Variation and Ecological Genetics of Blue Oak (Quercus douglasii Hook. & Am.)

Treesearch

Kevin J. Rice; Doria R. Gordon; Jeanine L. Hardison; Jeffrey M. Welker

1991-01-01

A field experiment was conducted to examine the effects of soil water availability on blue oak (Quercus douglasii) seedling establishment. Acorns were planted either into cleared plots of 0, 10, 20, or 40 cm diameter. The cleared plots were located in two grazed and one ungrazed site. Half of the plots received drip irrigation in a split plot design...

Plant community development after 28 years in small group-selection openings

Treesearch

Philip M. McDonald; Phillip E. Reynolds

1999-01-01

Thirty openings, 9, 18, and 27 meters in diameter, were created by group-selection harvest on a high quality site in northern California in 1963. In 1991, or 28 years after site preparation, the plant community in the openings had stabilized at 55 species. A major shift was from annuals to perennials. New seedlings of ponderosa and sugar pine were able to become...

Precommercial crop-tree release increases diameter growth of Appalachian hardwood saplings

Treesearch

H. Clay Smith; Neil I. Lamson

1983-01-01

Codominant seedling-origin crop trees 25 to 39 feet tall in even-aged, precommercial-size hardwood stands were released in West Virginia. Trees were located on two sites: good oak site index 75 and fair oak site 63. Species studied were black cherry, sweet birch, and yellow-poplar. Three-year results indicated that the trees generally responded to release; the 3-year...

Lodgepole pine development after early spacing in the Blue Mountains of Oregon.

Treesearch

P.H. Cochran; Walter G. Dahms

1998-01-01

Seedlings were thinned to spacings of 6, 9, 12, 15, and 18 feet and measured periodically. Twenty-seven years later, height did not differ with spacing, but diameters increased while basal areas and cubic volumes decreased as spacing widened. Simulation to age 100 years indicated that about the same board volume would be produced at 12-, 15-, and 18-foot spacings....

Seedling-sapling growth variation in a southern Illinios black walnut provenance/progeny test

Treesearch

George Rink; J. W. Van Sambeek

1987-01-01

Nursery root and shoot measurements and annual height, basal diameter and survival data for the 5 years after outplanting were used to describe black walnut growth variation in southern Illinois. At age 5 sapling height narrow-sense heritability was found to be 0.49 for 131 open-pollinated families from across the black walnut comercial range. Greatest height and...

Branching of the PIF3 regulatory network in Arabidopsis: roles of PIF3-regulated MIDAs in seedling development in the dark and in response to light.

PubMed

Sentandreu, Maria; Leivar, Pablo; Martín, Guiomar; Monte, Elena

2012-04-01

Plants need to accurately adjust their development after germination in the underground darkness to ensure survival of the seedling, both in the dark and in the light upon reaching the soil surface. Recent studies have established that the photoreceptors phytochromes and the bHLH phytochrome interacting factors PIFs regulate seedling development to adjust it to the prevailing light environment during post-germinative growth. However, complete understanding of the downstream regulatory network implementing these developmental responses is still lacking. In a recent work, published in The Plant Cell, we report a subset of PIF3-regulated genes in dark-grown seedlings that we have named MIDAs (MISREGULATED IN DARK). Analysis of their functional relevance using mutants showed that four of them present phenotypic alterations in the dark, and that each affected a particular facet of seedling development, suggesting organ-specific branching in the signal that PIF3 relays downstream. Furthermore, our results also showed an altered response to light in seedlings with an impaired PIF3/MIDA regulatory network, indicating that these factors might also be essential to initiate and optimize the developmental adjustment of the seedling to the light environment.

The introduced tree Prosopis juliflora is a serious threat to native species of the Brazilian Caatinga vegetation.

PubMed

de Souza Nascimento, Clóvis Eduardo; Tabarelli, Marcelo; da Silva, Carlos Alberto Domingues; Leal, Inara Roberta; de Souza Tavares, Wagner; Serrão, José Eduardo; Zanuncio, José Cola

2014-05-15

Despite its economic importance in the rural context, the Prosopis juliflora tree species has already invaded millions of hectares globally (particularly rangelands), threatening native biodiversity and rural sustainability. Here we examine seedling growth (leaf area, stem diameter, plant height) and seedling mortality across five native plant species of the Caatinga vegetation in response to competition with P. juliflora. Two sowing treatments with 10 replications were adopted within a factorial 2 × 5 randomized block design. Treatments consisted of P. juliflora seeds sowed with seeds of Caesalpinia ferrea, Caesalpinia microphylla, Erythrina velutina, Mimosa bimucronata and Mimosa tenuiflora (one single native species per treatment), while seeds of native species sowed without P. juliflora were adopted as controls. Overall, our results suggest that P. juliflora can reduce seedling growth by half and cause increased seedling mortality among woody plant species. Moreover, native species exhibit different levels of susceptibility to competition with P. juliflora, particularly in terms of plant growth. Such a superior competitive ability apparently permits P. juliflora to establish monospecific stands of adult trees, locally displacing native species or limiting their recruitment. The use of less sensitive species, such as C. ferrea and M. tenuiflora, to restore native vegetation before intensive colonization by P. juliflora should be investigated as an effective approach for avoiding its continuous spread across the Caatinga region. Copyright © 2014 Elsevier B.V. All rights reserved.

Factors affecting establishment success of the endangered Caribbean cactus Harrisia portoricensis (Cactaceae).

PubMed

Rojas-Sandoval, Julissa; Meléndez-Ackerman, Elvia

2012-06-01

Early plant stages may be the most vulnerable within the life cycle of plants especially in arid ecosystems. Interference from exotic species may exacerbate this condition. We evaluated germination, seedling survival and growth in the endangered Caribbean cactus Harrisia portoricensis, as a function of sunlight exposure (i.e., growing under open and shaded areas), different shade providers (i.e., growing under two native shrubs and one exotic grass species), two levels of predation (i.e., exclusion and non-exclusion) and variable microenvironmental conditions (i.e., temperature, PAR, humidity). Field experiments demonstrated that suitable conditions for germination and establishment of H. portoricensis seedling are optimal in shaded areas beneath the canopy of established species, but experiments also demonstrated that the identity of the shade provider can have a significant influence on the outcome of these processes. Harrisia portoricensis seedlings had higher probabilities of survival and grew better (i.e., larger diameters) when they were transplanted beneath the canopy of native shrubs, than beneath the exotic grass species, where temperature and solar radiation values were on average much higher than those obtained under the canopies of native shrubs. We also detected that exclusion from potential predators did not increase seedling survival. Our combined results for H. portoricensis suggested that the modification of microenvironmental conditions by the exotic grass may lower the probability of recruitment and establishment of this endangered cactus species.

Desiccation Tolerance of Five Tropical Seedlings in Panama. Relationship to a Field Assessment of Drought Performance1

PubMed Central

Tyree, Melvin T.; Engelbrecht, Bettina M.J.; Vargas, Gustavo; Kursar, Thomas A.

2003-01-01

Studies of the desiccation tolerance of the seedlings of five tropical trees were made on potted plants growing in a greenhouse. Pots were watered to field capacity and then dehydrated for 3 to 9 weeks to reach various visual wilting stages, from slightly wilted to dead. Saturated root hydraulic conductance was measured with a high-pressure flowmeter, and whole-stem hydraulic conductance was measured by a vacuum chamber method. Leaf punches (5.6-mm diameter) were harvested for measurement of leaf water potential by a thermocouple psychrometer method and for measurement of fresh and dry weight. In a parallel study, the same five species were studied in a field experiment in the understory of a tropical forest, where these species frequently germinate. Control seedlings were maintained in irrigated plots during a dry season, and experimental plants were grown in similar plots with rain exclusion shelters. Every 2 to 4 weeks, the seedlings were scored for wilt state and survivorship. After a 22-week drought, the dry plots were irrigated for several weeks to verify visual symptoms of death. The field trials were used to rank drought performance of species, and the greenhouse desiccation studies were used to determine the conditions of moribund plants. Our conclusion is that the desiccation tolerance of moribund plants correlated with field assessment of drought-performance for the five species (r2 > 0.94). PMID:12857825

Desiccation tolerance of five tropical seedlings in panama. Relationship to a field assessment of drought performance.

PubMed

Tyree, Melvin T; Engelbrecht, Bettina M J; Vargas, Gustavo; Kursar, Thomas A

2003-07-01

Studies of the desiccation tolerance of the seedlings of five tropical trees were made on potted plants growing in a greenhouse. Pots were watered to field capacity and then dehydrated for 3 to 9 weeks to reach various visual wilting stages, from slightly wilted to dead. Saturated root hydraulic conductance was measured with a high-pressure flowmeter, and whole-stem hydraulic conductance was measured by a vacuum chamber method. Leaf punches (5.6-mm diameter) were harvested for measurement of leaf water potential by a thermocouple psychrometer method and for measurement of fresh and dry weight. In a parallel study, the same five species were studied in a field experiment in the understory of a tropical forest, where these species frequently germinate. Control seedlings were maintained in irrigated plots during a dry season, and experimental plants were grown in similar plots with rain exclusion shelters. Every 2 to 4 weeks, the seedlings were scored for wilt state and survivorship. After a 22-week drought, the dry plots were irrigated for several weeks to verify visual symptoms of death. The field trials were used to rank drought performance of species, and the greenhouse desiccation studies were used to determine the conditions of moribund plants. Our conclusion is that the desiccation tolerance of moribund plants correlated with field assessment of drought-performance for the five species (r(2) > 0.94).

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.

Early root cap development and graviresponse in white clover (Trifolium repens) grown in space and on a two-axis clinostat

NASA Technical Reports Server (NTRS)

Smith, J. D.; Staehelin, L. A.; Todd, P.

1999-01-01

White clover (Trifolium repens) was germinated and grown in microgravity aboard the Space Shuttle (STS-60, 1994; STS-63, 1995), on Earth in stationary racks and in a slow-rotating two-axis clinostat. The objective of this study was to determine if normal root cap development and early plant gravity responses were dependent on gravitational cues. Seedlings were germinated in space and chemically fixed in orbit after 21, 40, and 72 h. Seedlings 96 h old were returned viable to earth. Germination and total seedling length were not dependent on gravity treatment. In space-flown seedlings, the number of cell stories in the root cap and the geometry of central columella cells did not differ from those of the Earth-grown seedlings. The root cap structure of clinorotated plants appeared similar to that of seedlings from microgravity, with the exception of three-day rotated plants, which displayed significant cellular damage in the columella region. Nuclear polarity did not depend on gravity; however, the positions of amyloplasts in the central columella cells were dependent on both the gravity treatment and the age of the seedlings. Seedlings from space, returned viable to earth, responded to horizontal stimulation as did 1 g controls, but seedlings rotated on the clinostat for the same duration had a reduced curvature response. This study demonstrates that initial root cap development is insensitive to either chronic clinorotation or microgravity. Soon after differentiation, however, clinorotation leads to loss of normal root cap structure and plant graviresponse while microgravity does not.

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

Long-term impact of aerial application of 2,4,5-T to longleaf pine (Pinus palustris)

Treesearch

J.L. Michael

1980-01-01

Twenty years after aerial application of 2.24 kg ae/ha of the butoxy ethanol ester of 2,4,5-T [(2,4,5-trichlorophenoxy) acetic acid] to release grass stage longleaf pine (Pinus palustris Mill.) seedlings, stocking was the same for each of the three treated and control 4-ha plots. Treated plots, however, had significantly greater tree diameter (10%),...

Artificially regenerating longleaf pine on wet sites: preliminary analysis of effects of site preparation treatments on early survival and growth

Treesearch

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

2010-01-01

Our study, conducted over two years on poorly drained, sandy sites in Onslow County, NC, compared the effects of eight common site preparation treatments on early survival and growth of planted longleaf pine seedlings. Through two growing seasons, we found survival to be similar across all treatments (p = 0.8806), but root collar diameter was greatest with combinations...

Growth and wood/bark properties of Abies faxoniana seedlings as affected by elevated CO2.

PubMed

Qiao, Yun-Zhou; Zhang, Yuan-Bin; Wang, Kai-Yun; Wang, Qian; Tian, Qi-Zhuo

2008-03-01

Growth and wood and bark properties of Abies faxoniana seedlings after one year's exposure to elevated CO2 concentration (ambient + 350 (+/- 25) micromol/mol) under two planting densities (28 or 84 plants/m(2)) were investigated in closed-top chambers. Tree height, stem diameter and cross-sectional area, and total biomass were enhanced under elevated CO2 concentration, and reduced under high planting density. Most traits of stem bark were improved under elevated CO2 concentration and reduced under high planting density. Stem wood production was significantly increased in volume under elevated CO2 concentration under both densities, and the stem wood density decreased under elevated CO2 concentration and increased under high planting density. These results suggest that the response of stem wood and bark to elevated CO2 concentration is density dependent. This may be of great importance in a future CO2 enriched world in natural forests where plant density varies considerably. The results also show that the bark/wood ratio in diameter, stem cross-sectional area and dry weight are not proportionally affected by elevated CO2 concentration under the two contrasting planting densities. This indicates that the response magnitude of stem bark and stem wood to elevated CO2 concentration are different but their response directions are the same.

Mechanical impedance of soil crusts and water content in loamy soils

NASA Astrophysics Data System (ADS)

Josa March, Ramon; Verdú, Antoni M. C.; Mas, Maria Teresa

2013-04-01

Soil crust development affects soil water dynamics and soil aeration. Soil crusts act as mechanical barriers to fluid flow and, as their mechanical impedance increases with drying, they also become obstacles to seedling emergence. As a consequence, the emergence of seedling cohorts (sensitive seeds) might be reduced. However, this may be of interest to be used as an effective system of weed control. Soil crusting is determined by several factors: soil texture, rain intensity, sedimentation processes, etc. There are different ways to characterize the crusts. One of them is to measure their mechanical impedance (MI), which is linked to their moisture level. In this study, we measured the evolution of the mechanical impedance of crusts formed by three loamy soil types (clay loam, loam and sandy clay loam, USDA) with different soil water contents. The aim of this communication was to establish a mathematical relationship between the crust water content and its MI. A saturated soil paste was prepared and placed in PVC cylinders (50 mm diameter and 10 mm height) arranged on a plastic tray. Previously the plastic tray was sprayed with a hydrophobic liquid to prevent the adherence of samples. The samples on the plastic tray were left to air-dry under laboratory conditions until their IM was measured. To measure IM, a food texture analyzer was used. The equipment incorporates a mobile arm, a load cell to apply force and a probe. The arm moves down vertically at a constant rate and the cylindrical steel probe (4 mm diameter) penetrates the soil sample vertically at a constant rate. The equipment is provided with software to store data (time, vertical distance and force values) at a rate of up to 500 points per second. Water content in crust soil samples was determined as the loss of weight after oven-drying (105°C). From the results, an exponential regression between MI and the water content was obtained (determination coefficient very close to 1). This methodology allows the prediction of the potential mechanical behaviour of soil crusts generated during soil drying, from initial saturated soil conditions (e.g. waterlogging conditions).

Stem anatomy and relative growth rate in seedlings of a wide range of woody plant species and types.

PubMed

Castro-Díez, P; Puyravaud, J P; Cornelissen, J H C; Villar-Salvador, P

1998-08-01

Stem traits were analysed in laboratory-grown seedlings of 80 European woody and semiwoody species of known potential relative growth rate (RGR) and of similar ontogenetic phase. The objectives were, firstly, to assess the relation between stem structure and plant growth potential and, secondly, to explore how stem structure varies among species differing in life form and leaf habit. Hydraulic conductance was represented by the mean diameter of the widest xylem conduits (Dmax), and structural strength by the percentage of xylem tissue occupied by cell wall material (CWx) or stem tissue density (SD). Across all species RGR showed a weak positive correlation with Dmax and weak negative ones with CWx and SD, with slow-growers showing great dispersion of stem trait values. In the RGR-Dmax relationship this dispersion disappeared when trees were removed from the analysis. None of the relationships were significant among tree species alone. It was suggested that fast-growers require a xylem with wide conduits (high Dmax) to achieve high hydraulic conductivity, and "cheaply" constructed stems (low CWx and SD) to maximise allocation to leaves. However, the possession of such traits does not guarantee fast growth, as other factors may constrain RGR elsewhere in the plant. Deciduous seedlings showed higher Dmax and lower CWx than evergreens. Higher Dmax could reflect an innate higher tolerance of conductivity loss by freeze-induced embolism in deciduous plants, which are not burdened by the maintenance of foliage in winter. In contrast, life forms were differentiated most clearly by SD. For instance, shrub seedlings had less dense stem tissues than tree seedlings, possibly because they need less investment in long-term strength and stature.

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.

Phenylalanine Is Required to Promote Specific Developmental Responses and Prevents Cellular Damage in Response to Ultraviolet Light in Soybean (Glycine max) during the Seed-to-Seedling Transition

PubMed Central

Sullivan, Joe H.; Muhammad, DurreShahwar; Warpeha, Katherine M.

2014-01-01

UV-radiation elicits a suite of developmental (photomorphogenic) and protective responses in plants, but responses early post-germination have received little attention, particularly in intensively bred plants of economic importance. We examined germination, hypocotyl elongation, leaf pubescence and subcellular responses of germinating and/or etiolated soybean (Glycine max (L.) Merr.) seedlings in response to treatment with discrete wavelengths of UV-A or UV-B radiation. We demonstrate differential responses of germinating/young soybean seedlings to a range of UV wavelengths that indicate unique signal transduction mechanisms regulate UV-initiated responses. We have investigated how phenylalanine, a key substrate in the phenylpropanoid pathway, may be involved in these responses. Pubescence may be a key location for phenylalanine-derived protective compounds, as UV-B irradiation increased pubescence and accumulation of UV-absorbing compounds within primary leaf pubescence, visualized by microscopy and absorbance spectra. Mass spectrometry analysis of pubescence indicated that sinapic esters accumulate in the UV-irradiated hairs compared to unirradiated primary leaf tissue. Deleterious effects of some UV-B wavelengths on germination and seedling responses were reduced or entirely prevented by inclusion of phenylalanine in the growth media. Key effects of phenylalanine were not duplicated by tyrosine or tryptophan or sucrose, nor is the specificity of response due to the absorbance of phenylalanine itself. These results suggest that in the seed-to-seedling transition, phenylalanine may be a limiting factor in the development of initial mechanisms of UV protection in the developing leaf. PMID:25549094

Ash content, carbon and C/N ratio in paricá in function of NPK fertilization.

PubMed

Vieira, Cristiane R; Weber, Oscarlina L S; Scaramuzza, José Fernando

2018-01-01

Fertilization in areas of forest plantations is needed to supplement plants´ nutritional needs until harvest. An experiment was performed to check the influence of fertilization on levels of ash, carbon and C/N relation in Schizolobium amazonicum. Soil liming was performed and fertilization occurred after 15 days of incubation. S. amazonicum seedlings were produced and submitted to fertilization with N, P and K: N = 0, 40, 80 and 120 kg ha-1; P2O5 = 0, 50, 100 and 200 kg ha-1; K2O = 0, 50, 100 and 200 kg ha-1. The plants were measured after 180 days. The seedlings of 20 treatments with the highest increase in height and diameter were transplanted to the field. Soil was fertilized and limestone was spread; seedlings were distributed into randomized blocks, with six replications. After 12 months, the plants were removed to determine ash, organic carbon, C/N relation contents. The ashes were submitted to digestion to determine nutrient concentrations. Fertilization influenced the levels of ash and organic carbon and C/N relation in S. amazonicum. Results indicate that the species has a potential for energy production.

Effects of soil cadmium on growth of bald cypress seedlings under flooded and non-flooded conditions

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

Fredenberg, S.C.; Neufeld, H.S.

1995-06-01

Cypress swamps are occasionally used for tertiary waste water treatment. The sewage input to these ecosystems often contains high amounts of cadmium. To date, there have been no studies of the potential effects of cadmium on the growth of the dominant trees in these swamps, the bald cypress (Taxodium distichum (L.) Rich. var. distichum). Seedlings were grown for 16 weeks in organic soils amended with 0, 40, 80, and 120 ppm Cd (mg Cd/Kg soil dry weight) under both flooded and non-flooded conditions. Near the end of the growth period, leaf gas exchange was measured using a Li-Cor portable system.more » At the conclusion of the experiment, seedlings were harvested and separated into leaves, stems, branches and roots and dried at 65 C. Cadmium had no significant effects on any measured parameter. Flooding did Increase stem diameter, while decreasing height and biomass, but it had no effect on tolerance to Cd. Flooding reduced total biomass by 35%, mainly due to greatly reduced root growth (66% reduction). Cypress trees were probably protected from the toxic effects of Cd by the binding of this heavy metal to organic compounds in the soil.« less

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.

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.

Are tree ontogenetic structure and allometric relationship independent of vegetation formation type? A case study with Cordia oncocalyx in the Brazilian caatinga

NASA Astrophysics Data System (ADS)

Silveira, Andréa P.; Martins, Fernando R.; Araújo, Francisca S.

2012-08-01

In temperate and tropical rainforests, ontogenetic structure and allometry during tree ontogeny are often associated with light gradients. Light is not considered a limiting resource in deciduous thorny woodland (DTW), but establishment and growth occur during a short rainy period, when the canopy is fully leaved and light in the understory may be modified. Our aim was to investigate whether the light gradient in DTW and the biomechanical limitations of tree growth would be enough to produce an ontogenetic structure and allometric growth similar to rainforest canopy trees. We investigated the ontogenetic stages and diameter-height relationship of Cordia oncocalyx (Boraginaceae), a dominant canopy tree of the DTW of semiarid northeastern Brazil. We tagged, measured and classified the ontogenetic stages of 2.895 individuals in a 1 ha area (5°6'58.1″S and 40°52'19.4″W). In the rainy season only 4.7% of the light falling on the canopy reached the ground. Initial ontogenetic stages, mainly infant (50.9%) and seedling (42.1%), were predominant in the population, with the remaining 7% distributed among juvenile, immature, virginile and reproductive. The ontogenetic structure was similar to that of rainforest tree species, but the population formed both permanent seed and infant banks in response to long dry periods and erratic rainy spells. Like many other Boraginaceae tree species in tropical rainforests, C. oncocalyx has a Prévost architectural model, but allometric growth was quite different from rainforest trees. C. oncocalyx invested slightly more in diameter at first, then in height and finally invested greatly in diameter and attained an asymptotic height. The continued high investment in diameter growth at late stages and the asymptotic height point to low tree density and more frequent xylem embolism as the main drivers of tree allometric shape in DTW. This indicates that tree ontogenetic structure and allometric relationships depend on vegetation formation type.

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

[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.

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

Sensitivity of cold acclimation to elevated autumn temperature in field-grown Pinus strobus seedlings

PubMed Central

Chang, Christine Y.; Unda, Faride; Zubilewich, Alexandra; Mansfield, Shawn D.; Ensminger, Ingo

2015-01-01

Climate change will increase autumn air temperature, while photoperiod decrease will remain unaffected. We assessed the effect of increased autumn air temperature on timing and development of cold acclimation and freezing resistance in Eastern white pine (EWP, Pinus strobus) under field conditions. For this purpose we simulated projected warmer temperatures for southern Ontario in a Temperature Free-Air-Controlled Enhancement (T-FACE) experiment and exposed EWP seedlings to ambient (Control) or elevated temperature (ET, +1.5°C/+3°C during day/night). Photosynthetic gas exchange, chlorophyll fluorescence, photoprotective pigments, leaf non-structural carbohydrates (NSC), and cold hardiness were assessed over two consecutive autumns. Nighttime temperature below 10°C and photoperiod below 12 h initiated downregulation of assimilation in both treatments. When temperature further decreased to 0°C and photoperiod became shorter than 10 h, downregulation of the light reactions and upregulation of photoprotective mechanisms occurred in both treatments. While ET seedlings did not delay the timing of the downregulation of assimilation, stomatal conductance in ET seedlings was decreased by 20–30% between August and early October. In both treatments leaf NSC composition changed considerably during autumn but differences between Control and ET seedlings were not significant. Similarly, development of freezing resistance was induced by exposure to low temperature during autumn, but the timing was not delayed in ET seedlings compared to Control seedlings. Our results indicate that EWP is most sensitive to temperature changes during October and November when downregulation of photosynthesis, enhancement of photoprotection, synthesis of cold-associated NSCs and development of freezing resistance occur. However, we also conclude that the timing of the development of freezing resistance in EWP seedlings is not affected by moderate temperature increases used in our field experiments. PMID:25852717

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.

Impacts of Rate of Hexazinone Application on Survival and Growth of the Loblolly Pine

Treesearch

J.L. Michael

1984-01-01

Hexazinone [3-cyc1ohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H, 3H)-dionel in 2-cc pellets (10% active ingredient) was applied at rates of 0,2,4, and 8 pounds of active ingredient per acre for site preparation on clay soil in a randomized experiment in May 1980. Loblolly pine seedlings planted to the site in January 1981 were measured for diameter 3 inches...

Do deer and shrubs override canopy gap size effects on growth and survival of yellow birch, northern red oak, eastern white pine, and eastern hemlock seedlings?

Treesearch

Cristel C. Kern; Peter B. Reich; Rebecca A. Montgomery; Terry F. Strong

2012-01-01

Innovative forestry practices that use natural disturbance and stand developmental processes as models to increase forest complexity are now being considered as a way to conserve biodiversity while managing for a range of objectives.We evaluated the influence of harvest-created gap size (6, 10, 20, 30, and 46 m diameter gaps and uncut references) over 12 growing...

Estimates of biomass in logging residue and standing residual inventory following tree-harvest activity on timberland acres in the southern region

Treesearch

Roger C. Conner; Tony G. Johnson

2011-01-01

This report provides estimates of biomass (green tons) in logging residue and standing residual inventory on timberland acres with evidence of tree cutting. Biomass as defined by Forest Inventory and Analysis is the aboveground dry weight of wood in the bole and limbs of live trees ≥ 1-inch diameter at breast height (d.b.h.), and excludes tree foliage, seedlings, and...

Trends in Genetic and Environmental Parameters for Height, Diameter, and Volume in a Multilocation Clonal Study with Loblolly Pine

Treesearch

A.D. Paul; G. Sam Foster; T. Caldwell; J. McRae

1997-01-01

Seedlings from 30 full-sib families (contained in 2,4 x 4 factorials) of loblollynine(Pinus taeda L.) were cloned and planted in three test sites in Georgia. Analyses were conducted on total height at ages 1 to 5 yr in the field, dbh at age 5, and individual tree volume at age 5. Four sources of genetic control were tested: male parent, female parent, male x female...

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.

Experiments Testing the Causes of Namibian Fairy Circles.

PubMed

Tschinkel, Walter R

2015-01-01

The grasslands on the sandy soils of the eastern edge of the Namib Desert of Namibia are strikingly punctuated by millions of mostly regularly-spaced circular bare spots 2 to 10 m or more in diameter, generally with a margin of taller grasses. The causes of these so called fairy circles are unknown, but several hypotheses have been advanced. In October 2009, we set up experiments that specifically tested four hypothesized causes, and monitored these 5 times between 2009 and 2015. Grass exclusion in circles due to seepage of subterranean vapors or gases was tested by burying an impermeable barrier beneath fairy circles, but seedling density and growth did not differ from barrier-less controls. Plant germination and growth inhibition by allelochemicals or nutrient deficiencies in fairy circle soils were tested by transferring fairy circle soil to artificially cleared circles in the grassy matrix, and matrix soil to fairy circles (along with circle to circle and matrix to matrix controls). None of the transfers changed the seedling density and growth from the control reference conditions. Limitation of plant growth due to micronutrient depletion within fairy circles was tested by supplementing circles with a micronutrient mixture, but did not result in differences in plant seedling density and growth. Short-range vegetation competitive feedbacks were tested by creating artificially-cleared circles of 2 or 4 m diameter located 2 or 6 m from a natural fairy circle. The natural circles remained bare and the artificial circles revegetated. These four experiments provided evidence that fairy circles were not caused by subterranean vapors, that fairy circle soil per se did not inhibit plant growth, and that the circles were not caused by micronutrient deficiency. There was also no evidence that vegetative feedbacks affected fairy circles on a 2 to 10 m scale. Landscape-scale vegetative self-organization is discussed as a more likely cause of fairy circles.

The response of mulberry trees after seedling hardening to summer drought in the hydro-fluctuation belt of Three Gorges Reservoir Areas.

PubMed

Huang, Xiaohui; Liu, Yun; Li, Jiaxing; Xiong, Xingzheng; Chen, Yang; Yin, Xiaohua; Feng, Dalan

2013-10-01

Interest has developed in the potential of mulberry (Morus alba), a woody perennial, for revegetating the hydro-fluctuation belt of the Three Gorges Reservoir due to its resistance to water-logging stress. To be useful, the trees must also be able to withstand dry conditions in summer when temperatures can be very high and droughts become severe quickly. Here, we report a study in which mulberry seedlings were grown in a greenhouse under a variety of simulated soil water conditions reflecting potential summer scenarios in the hydro-fluctuation belt of the Three Gorges Reservoir Area. We compared the responses of two pretreatment groups of mulberry seedlings to different levels of drought stress. The pretreatment groups differed with respect to drought hardening: the daily-managed (DM) group had relative soil moisture held constant in the range 70-80 %, while the drought-hardened (DH) group had relative soil moisture held constant at 40-50 %. Following the month-long pretreatment of seedlings, the two groups of young trees (DM and DH) were then respectively subjected to three levels of drought stress for a month: normal watering, moderate drought stress, and severe drought stress. A series of measurements comparing the physiological status of the plants in the two groups were then made, and the following results were obtained: (1) As drought stress increased, the heights, base diameters, root surface areas, photosynthetic rates (Pn), stomatal conductances (Gs), and transpiration rates (Tr) of the mulberry trees in both groups (DM and DH) decreased significantly, while the specific root area and abscisic acid (ABA) contents had increasing trends. Root activity and instantaneous water use efficiency of mulberry trees in both groups (DM and DH) were all raised under drought stress conditions than under normal watering, but the root/shoot ratio and leaf water potential were lowered. (2) At the same level of soil water content, the heights, base diameters, root/shoot ratios, root surface areas, specific root areas, photosynthetic rates (Pn), stomatal conductances (Gs), and transpiration rates (Tr) of the young mulberry trees in the DH were all significantly higher than those of the control group (DM). Leaf water potential, instantaneous water use efficiency, and abscisic acid content of DH were all significantly lower than DM. Under different degrees of drought stress, the growth of mulberry trees will be inhibited, but the trees can respond to the stress by increasing the root absorptive area and enhancing capacity for water retention. Mulberry trees demonstrate strong resistance to drought stress, and furthermore drought resistance can be improved by drought hardening during the seedling stage.

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.

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.

Interaction of copper nanoparticles and an endophytic growth promoter Piriformospora indica with Cajanus cajan.

PubMed

Rajak, Jyoti; Bawaskar, Manisha; Rathod, Dnyaneshwar; Agarkar, Gauravi; Nagaonkar, Dipali; Gade, Aniket; Rai, Mahendra

2017-10-01

In recent years, agro-bionanotechnology has paved the way towards revolutionizing current practices in the food and agricultural fields. In the present study, the effect of copper nanoparticles (CuNPs) alone and in combination with the growth-promoting fungus Piriformospora indica on 2-week-old seedlings of Cajanus cajan was evaluated. Gelatin-coated stable CuNPs were synthesized by the chemical reduction method using hydrazine hydrate as a reducing agent. CuNPs were characterized by using UV-visible spectroscopy, zeta potential measurement and transmission electron microscopy. The nanoparticles were found to be quite spherical with a diameter within the range 40 ± 10 nm. After the application of CuNPs and P. indica to the host plant C. cajan, the vitality of plants was determined using a Handy-PEA (plant efficiency analyzer) instrument. Handy-PEA analysis (which measures chlorophyll a fluorescence) indicated that seedlings inoculated with a combination of CuNPs and P. indica were the healthiest and also showed maximum vitality as compared to seedlings inoculated with CuNPs or P. indica alone. These results suggest that CuNPs in combination with P. indica can serve as a nanobiofertilizer for enhancement of the growth and productivity of C. cajan. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Exogenous glutathione improves high root-zone temperature tolerance by modulating photosynthesis, antioxidant and osmolytes systems in cucumber seedlings

PubMed Central

Ding, Xiaotao; Jiang, Yuping; He, Lizhong; Zhou, Qiang; Yu, Jizhu; Hui, Dafeng; Huang, Danfeng

2016-01-01

To investigate the physiological responses of plants to high root-zone temperature (HT, 35 °C) stress mitigated by exogenous glutathione (GSH), cucumber (Cucumis sativus L.) seedlings were exposed to HT with or without GSH treatment for 4 days and following with 4 days of recovery. Plant physiological variables, growth, and gene expression related to antioxidant enzymes and Calvin cycle were quantified. The results showed that HT significantly decreased GSH content, the ratio of reduced to oxidized glutathione (GSH/GSSG), chlorophyll content, photosynthesis and related gene expression, shoot height, stem diameter, as well as dry weight. The exogenous GSH treatment clearly lessened the HT stress by increasing the above variables. Meanwhile, HT significantly increased soluble protein content, proline and malondialdehyde (MDA) content as well as O2•− production rate, the gene expression and activities of antioxidant enzymes. The GSH treatment remarkably improved soluble protein content, proline content, antioxidant enzymes activities, and antioxidant enzymes related gene expression, and reduced the MDA content and O2•− production rate compared to no GSH treatment in the HT condition. Our results suggest that exogenous GSH enhances cucumber seedling tolerance of HT stress by modulating the photosynthesis, antioxidant and osmolytes systems to improve physiological adaptation. PMID:27752105

Arbuscular mycorrhizal fungi increased early growth of two nontimber forest product species Dyera polyphylla and Aquilaria filaria under greenhouse conditions.

PubMed

Turjaman, Maman; Tamai, Yutaka; Santoso, Erdy; Osaki, Mitsuru; Tawaraya, Keitaro

2006-10-01

Nontimber forest products (NTFPs) represent an important source of income to millions of people in tropical forest regions, but some NTFP species have decreased in number and become endangered due to overexploitation. There is increasing concern that the planting stocks of Dyera polyphylla and Aquilaria filaria are not sufficient to sustain the yield of NTFPs and promote forest conservation. The objective of this study was to determine the effect of two arbuscular mycorrhizal (AM) fungi, Glomus clarum and Gigaspora decipiens, on the early growth of two NTFP species, D. polyphylla and A. filaria, under greenhouse conditions. The seedlings of both species were inoculated with G. clarum or G. decipiens, or uninoculated (control) under greenhouse conditions. Percentage of AM colonization, plant growth, survival rate, and nitrogen (N) and phosphorus (P) concentrations were measured after 180 days of growth. The percentage of AM colonization of D. polyphylla and A. filaria ranged from 87 to 93% and from 22 to 39%, respectively. Colonization by G. clarum and G. decipiens increased plant height, diameter, and shoot and root dry weights. Shoot N and P concentrations of the seedlings were increased by AM colonization by as much as 70-153% and 135-360%, respectively. Survival rates were higher in the AM-colonized seedlings at 180 days after transplantation than in the control seedlings. The results suggest that AM fungi can accelerate the establishment of the planting stocks of D. polyphylla and A. filaria, thereby promoting their conservation ecologically and sustaining the production of these NTFPs economically.

Growth phenology of coast Douglas-fir seed sources planted in diverse environments.

PubMed

Gould, Peter J; Harrington, Constance A; St Clair, J Bradley

2012-12-01

The timing of periodic life cycle events in plants (phenology) is an important factor determining how species and populations will react to climate change. We evaluated annual patterns of basal-area and height growth of coast Douglas-fir (Pseudotusga menziesii var. menziesii (Mirb.) Franco) seedlings from four seed sources that were planted in four diverse environments as part of the Douglas-fir Seed-Source Movement Trial. Stem diameters and heights were measured periodically during the 2010 growing season on 16 open-pollinated families at each study installation. Stem diameters were measured on a subset of trees with electronic dendrometers during the 2010 and 2011 growing seasons. Trees from the four seed sources differed in phenology metrics that described the timing of basal-area and height-growth initiation, growth cessation and growth rates. Differences in the height-growth metrics were generally larger than differences in the basal-area growth metrics and differences among installations were larger than differences among seed sources, highlighting the importance of environmental signals on growth phenology. Variations in the height- and basal-area growth metrics were correlated with different aspects of the seed-source environments: precipitation in the case of height growth and minimum temperature in the case of basal-area growth. The detailed dendrometer measurements revealed differences in growth patterns between seed sources during distinct periods in the growing season. Our results indicate that multiple aspects of growth phenology should be considered along with other traits when evaluating adaptation of populations to future climates.

Clonal growth strategy, diversity and structure: A spatiotemporal response to sedimentation in tropical Cyperus papyrus swamps.

PubMed

Geremew, Addisie; Stiers, Iris; Sierens, Tim; Kefalew, Alemayehu; Triest, Ludwig

2018-01-01

Land degradation and soil erosion in the upper catchments of tropical lakes fringed by papyrus vegetation can result in a sediment load gradient from land to lakeward. Understanding the dynamics of clonal modules (ramets and genets) and growth strategies of plants on such a gradient in both space and time is critical for exploring a species adaptation and processes regulating population structure and differentiation. We assessed the spatial and temporal dynamics in clonal growth, diversity, and structure of an emergent macrophyte, Cyperus papyrus (papyrus), in response to two contrasting sedimentation regimes by combining morphological traits and genotype data using 20 microsatellite markers. A total of 636 ramets from six permanent plots (18 x 30 m) in three Ethiopian papyrus swamps, each with discrete sedimentation regimes (high vs. low) were sampled for two years. We found that ramets under the high sedimentation regime (HSR) were significantly clumped and denser than the sparse and spreading ramets under the low sedimentation regime (LSR). The HSR resulted in significantly different ramets with short culm height and girth diameter as compared to the LSR. These results indicated that C. papyrus ameliorates the effect of sedimentation by shifting clonal growth strategy from guerrilla (in LSR) to phalanx (in HSR). Clonal richness, size, dominance, and clonal subrange differed significantly between sediment regimes and studied time periods. Each swamp under HSR revealed a significantly high clonal richness (R = 0.80) as compared to the LSR (R = 0.48). Such discrepancy in clonal richness reflected the occurrence of initial and repeated seedling recruitment strategies as a response to different sedimentation regimes. Overall, our spatial and short-term temporal observations highlighted that HSR enhances clonal richness and decreases clonal subrange owing to repeated seedling recruitment and genets turnover.

Clonal growth strategy, diversity and structure: A spatiotemporal response to sedimentation in tropical Cyperus papyrus swamps

PubMed Central

Stiers, Iris; Sierens, Tim; Kefalew, Alemayehu; Triest, Ludwig

2018-01-01

Land degradation and soil erosion in the upper catchments of tropical lakes fringed by papyrus vegetation can result in a sediment load gradient from land to lakeward. Understanding the dynamics of clonal modules (ramets and genets) and growth strategies of plants on such a gradient in both space and time is critical for exploring a species adaptation and processes regulating population structure and differentiation. We assessed the spatial and temporal dynamics in clonal growth, diversity, and structure of an emergent macrophyte, Cyperus papyrus (papyrus), in response to two contrasting sedimentation regimes by combining morphological traits and genotype data using 20 microsatellite markers. A total of 636 ramets from six permanent plots (18 x 30 m) in three Ethiopian papyrus swamps, each with discrete sedimentation regimes (high vs. low) were sampled for two years. We found that ramets under the high sedimentation regime (HSR) were significantly clumped and denser than the sparse and spreading ramets under the low sedimentation regime (LSR). The HSR resulted in significantly different ramets with short culm height and girth diameter as compared to the LSR. These results indicated that C. papyrus ameliorates the effect of sedimentation by shifting clonal growth strategy from guerrilla (in LSR) to phalanx (in HSR). Clonal richness, size, dominance, and clonal subrange differed significantly between sediment regimes and studied time periods. Each swamp under HSR revealed a significantly high clonal richness (R = 0.80) as compared to the LSR (R = 0.48). Such discrepancy in clonal richness reflected the occurrence of initial and repeated seedling recruitment strategies as a response to different sedimentation regimes. Overall, our spatial and short-term temporal observations highlighted that HSR enhances clonal richness and decreases clonal subrange owing to repeated seedling recruitment and genets turnover. PMID:29338034

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.

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

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.

Response of young ponderosa pines, shrubs, and grasses to two release treatments. Forest Service research note

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

McDonald, P.M.; Everest, G.A.

1996-07-01

To release a young pine plantation on a medium site in central California, herbicides and mulches were applied soon after planting to study their effectiveness. Bearclover is an aggressive shrub species that resprouts from rhizomes after disturbance, and must be controlled if young conifer seedlings are to become established. After 4 years, resprouting bearclover plants numbered 282,000 per acre in the control, but less than 4,000 per acre in the plots treated by herbicides. Mean foliar cover was 63 percent versus 1 percent for control and herbicide plots, respectively. Ponderosa pine seedlings were significantly taller, had larger mean diameters, andmore » survived better in the herbicide treatment than counterparts in mulched plots and control. The 5-foot square mulches were ineffective for controlling bearclover. Cheatgrass invaded the plantation in the second year, and after 2 more years became abundant in herbicide plots and plentiful in the control.« less

Rhizophoraceae Mangrove Saplings Use Hypocotyl and Leaf Water Storage Capacity to Cope with Soil Water Salinity Changes

PubMed Central

Lechthaler, Silvia; Robert, Elisabeth M. R.; Tonné, Nathalie; Prusova, Alena; Gerkema, Edo; Van As, Henk; Koedam, Nico; Windt, Carel W.

2016-01-01

Some of the most striking features of Rhizophoraceae mangrove saplings are their voluminous cylinder-shaped hypocotyls and thickened leaves. The hypocotyls are known to serve as floats during seed dispersal (hydrochory) and store nutrients that allow the seedling to root and settle. In this study we investigate to what degree the hypocotyls and leaves can serve as water reservoirs once seedlings have settled, helping the plant to buffer the rapid water potential changes that are typical for the mangrove environment. We exposed saplings of two Rhizophoraceae species to three levels of salinity (15, 30, and 0–5‰, in that sequence) while non-invasively monitoring changes in hypocotyl and leaf water content by means of mobile NMR sensors. As a proxy for water content, changes in hypocotyl diameter and leaf thickness were monitored by means of dendrometers. Hypocotyl diameter variations were also monitored in the field on a Rhizophora species. The saplings were able to buffer rapid rhizosphere salinity changes using water stored in hypocotyls and leaves, but the largest water storage capacity was found in the leaves. We conclude that in Rhizophora and Bruguiera the hypocotyl offers the bulk of water buffering capacity during the dispersal phase and directly after settlement when only few leaves are present. As saplings develop more leaves, the significance of the leaves as a water storage organ becomes larger than that of the hypocotyl. PMID:27446125

Postfire regeneration in Cytisus oromediterraneus: sources of variation and morphology of the below-ground parts

NASA Astrophysics Data System (ADS)

Fernández-Santos, Belén; Martínez, Carolina; García, Jose A.; Puerto, Angel

2004-10-01

Postfire regeneration in Cytisus oromediterraneus, a Mediterranean-basin mountain matorral species, shows a wide range of possibilities and variations in sexual and asexual regeneration. Its interpretation requires basic information on the below-ground structure of parent plants as well as on the origin and development of seedlings and various ramet (sprout clump) types: rootstock, basal-branch, and lateral-root ramets. Morphology and emergence of such ramets in C. oromediterraneus is similar to that in related species but with some specific features described here in detail. In order to determine if characteristics of 1-year-old populations depended on the age of the burned parent plants, two populations were investigated: (A 7-year-old, and B 14-year-old). In the most frequent populations in our study area, i.e. those from parent populations of ca. 7 years (A): a—plant density and biomass were highly variable and positively correlated; b—frequency distribution differed significantly from normal distribution for plant weight, but not for other parameters such as diameters, perimeter, and height, in which it did, however, show asymmetry; c—perimeter was the best parameter for estimating individuals' weight; d—there was a higher number of seedlings than ramets but their biomass was smaller; e—the size of seedlings and ramets showed wide variation. In comparison with population A (7-year-old) population B (14-year-old) showed: significantly higher density, slightly lower biomass, higher number of small individuals, mainly seedlings, and less vigorous resprouting. In general, 1 year after fire, Cytisus oromeditarraneus population density mainly depends on the germination response, while the above-ground biomass mainly depends on the vegetative response and the intensity of both of them is conditioned by parent plant age.

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.

Growth and nutrition of baldcypress families planted under varying salinity regimes in Louisiana, USA

USGS Publications Warehouse

Krauss, K.W.; Chambers, J.L.; Allen, J.A.; Soileau, D.M.; DeBosier, A.S.

2000-01-01

Saltwater intrusion from the Gulf of Mexico is one important factor in the destruction of baldcypress (Taxodium distichum (L.) Rich.) swamps along the Louisiana Gulf Coast, USA. Recent restoration efforts have focused on identification of baldcypress genotypes with greater tolerance to saline conditions than previously reported. To date, salt tolerance investigations have not been conducted under saline field conditions. In 1996, therefore, three plantations were established with 10 half-sib genotype collections of baldcypress in mesohaline wetlands. Tree survival and growth were measured at the end of two growing seasons, and foliar ion concentrations of Na, Cl, K, and Ca and available soil nutrients were measured during the 1996 growing season. In general, soil nutrient concentrations exceeded averages found in other baldcypress stands in the southeastern United States. Seedlings differed among sites in all parameters measured, with height, diameter, foliar biomass, and survival decreasing as site salinity increased. Average seedling height at the end of two years, for example, was 196.4 cm on the lowest salinity site and 121.6 cm on the highest. Several half-sib families maintained greater height growth increments (ranging from 25.5 to 54.5 cm on the highest salinity site), as well as lower foliar ion concentrations of K, Cl, and Ca. Results indicate that genotypic screening of baldcypress may improve growth and vigor of seedlings planted within wetlands impacted by saltwater intrusion.

Productivity responses of Acer rubrum and Taxodium distichum seedlings to elevated CO2 and flooding

USGS Publications Warehouse

Vann, C.D.; Megonigal, J.P.

2002-01-01

Elevated levels of atmospheric CO2 are expected to increase photosynthetic rates of C3 tree species, but it is uncertain whether this will result in an increase in wetland seedling productivity. Separate short-term experiments (12 and 17 weeks) were performed on two wetland tree species, Taxodium distichum and Acer rubrum, to determine if elevated CO2 would influence the biomass responses of seedlings to flooding. T. distichum were grown in replicate glasshouses (n = 2) at CO2 concentrations of 350 or 700 ppm, and A. rubrum were grown in growth chambers at CO2 concentrations of 422 or 722 ppm. Both species were grown from seed. The elevated CO2 treatment was crossed with two water table treatments, flooded and non-flooded. Elevated CO2 increased leaf-level photosynthesis, whole-plant photosynthesis, and trunk diameter of T. distichum in both flooding treatments, but did not increase biomass of T. distichum or A. rubrum. Flooding severely reduced biomass, height, and leaf area of both T. distichum and A. rubrum. Our results suggest that the absence of a CO2-induced increase in growth may have been due to an O2 limitation on root production even though there was a relatively deep (??? 10 cm) aerobic soil surface in the non-flooded treatment. ?? 2001 Elsevier Science Ltd. All rights reserved.

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.

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

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

Independent effects and interactions of stand diameter, tree diameter, crown class, and age on tree growth in mixed-species, even-aged hardwood stands

Treesearch

D.A. Marquis

1991-01-01

Many studies have shown that initial tree diameter is closely correlated with subsequent tree growth. But initial tree diameter is actually a confounded variable, incorporating both competitive position (crown class) and age.

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.

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.

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

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.

Waterlogging in late dormancy and the early growth phase affected root and leaf morphology in Betula pendula and Betula pubescens seedlings.

PubMed

Wang, Ai-Fang; Roitto, Marja; Sutinen, Sirkka; Lehto, Tarja; Heinonen, Jaakko; Zhang, Gang; Repo, Tapani

2016-01-01

The warmer winters of the future will increase snow-melt frequency and rainfall, thereby increasing the risk of soil waterlogging and its effects on trees in winter and spring at northern latitudes. We studied the morphology of roots and leaves of 1-year-old silver birch (Betula pendula Roth) and pubescent birch (Betula pubescens Ehrh.) seedlings exposed to waterlogging during dormancy or at the beginning of the growing season in a growth-chamber experiment. The experiment included 4-week dormancy (Weeks 1-4), a 4-week early growing season (Weeks 5-8) and a 4-week late growing season (Weeks 9-12). The treatments were: (i) no waterlogging, throughout the experiment ('NW'); (ii) 4-week waterlogging during dormancy (dormancy waterlogging 'DW'); (iii) 4-week waterlogging during the early growing season (growth waterlogging 'GW'); and (iv) 4-week DW followed by 4-week GW during the early growing season ('DWGW'). Dormancy waterlogging affected the roots of silver birch and GW the roots and leaf characteristics of both species. Leaf area was reduced in both species by GW and DWGW. In pubescent birch, temporarily increased formation of thin roots was seen in root systems of GW seedlings, which suggests an adaptive mechanism with respect to excess soil water. Additionally, the high density of non-glandular trichomes and their increase in DWGW leaves were considered possible morphological adaptations to excess water in the soil, as was the constant density of stem lenticels during stem-diameter growth. The higher density in glandular trichomes of DWGW silver birch suggests morphological acclimation in that species. The naturally low density of non-glandular trichomes, low density of stem lenticels in waterlogged seedlings and decrease in root growth seen in DWGW and DW silver birch seedlings explain, at least partly, why silver birch grows more poorly relative to pubescent birch in wet soils. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Growth of Dalbergia sissoo in desert regions of western India using municipal effluent and the subsequent changes in soil and plant chemistry.

PubMed

Singh, G; Bhati, M

2005-06-01

Increasing demand for fodder and fuelwood and the scarcity of a good quality water in arid areas has resulted in a search for an alternative source of water for biomass production. An experiment utilizing municipal effluent in growing Dalbergia sissoo was conducted. Five treatments included T1, municipal effluent at 1 PET (Potential evapo-transpiration) (without plant); T2, municipal effluent at 1/2 PET; T3, municipal effluent at 1PET; T4, municipal effluent at 2 PET; and T5, canal water at 1 PET. Observations included plant height, collar diameter at one-month intervals and plant mineral composition, mineral uptake and changes in soil properties at 24 months of plant age. Application of municipal effluent produced better growth in D. sissoo seedlings. Concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) were greater in seedlings irrigated with municipal effluent than those of the seedlings irrigated by the treatment T5, and positively related with the quantity of irrigation. The concentrations were greatest in foliage compared to the other parts of seedling, with the exception of Cu concentration. Application of municipal effluents resulted in a 2- to 3-fold increase in the concentrations of soil K, Cu, Fe, Mn and Zn, whereas NH4-N and PO4-P availability increased by 8.1- and 4.5-fold, respectively. The increase in soil organic carbon was only observed in treatments T3 and T4. The accumulations of soil NO3-N, Na, Cu, Fe, Mn and Zn were more in lower soil layers but the other soil parameters showed their greatest values in the upper soil layer. Irrigation using municipal effluent did not result in toxicity to the seedlings before the age of 24 months. The results suggest that municipal effluent could be utilized, as an important source of water and nutrients in growing D. sissoo to increase biomass production in the needs of suburban dwellers. However, a preliminary treatment to reduce excess NH4-N and PO4-P will be required before application to the plantation.

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.

[Effects nutrients on the seedlings root hair development and root growth of Poncirus trifoliata under hydroponics condition].

PubMed

Cao, Xiu; Xia, Ren-Xue; Zhang, De-Jian; Shu, Bo

2013-06-01

Ahydroponics experiment was conducted to study the effects of nutrients (N, P, K, Ca, Mg, Fe, and Mn) deficiency on the length of primary root, the number of lateral roots, and the root hair density, length, and diameter on the primary root and lateral roots of Poncirus trifoliata seedlings. Under the deficiency of each test nutrient, root hair could generate, but was mainly concentrated on the root base and fewer on the root tip. The root hair density on lateral roots was significantly larger than that on primary root, but the root hair length was in adverse. The deficiency of each test nutrient had greater effects on the growth and development of root hairs, with the root hair density on primary root varied from 55.0 to 174.3 mm(-2). As compared with the control, Ca deficiency induced the significant increase of root hair density and length on primary root, P deficiency promoted the root hair density and length on the base and middle part of primary root and on the lateral roots significantly, Fe deficiency increased the root hair density but decreased the root hair length on the tip of primary root significantly, K deficiency significantly decreased the root hair density, length, and diameter on primary root and lateral roots, whereas Mg deficiency increased the root hair length of primary root significantly. In all treatments of nutrient deficiency, the primary root had the similar growth rate, but, with the exceptions of N and Mg deficiency, the lateral roots exhibited shedding and regeneration.

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.

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.

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.

Short pulse duration shock initiation experiments plus ignition and growth modeling on Composition B

NASA Astrophysics Data System (ADS)

May, Chadd M.; Tarver, Craig M.

2014-05-01

Composition B (63% RDX, 36% TNT, 1% wax) is still a widely used energetic material whose shock initiation characteristics are necessary to understand. It is now possible to shock initiate Composition B and other secondary explosives at diameters well below their characteristic failure diameters for unconfined self-sustaining detonation. This is done using very high velocity, very thin, small diameter flyer plates accelerated by electric or laser power sources. Recently experimental detonation versus failure to detonate threshold flyer velocity curves for Composition B using several KaptonTM flyer thicknesses and diameters were measured. Flyer plates with diameters of 2 mm successfully detonated Composition B, which has a nominal failure diameter of 4.3 mm. The shock pressures required for these initiations are greater than the Chapman-Jouguet (C-J) pressure in self-sustaining Composition B detonation waves. The initiation process is two-dimensional, because both rear and side rarefactions can affect the shocked Composition B reaction rates. The Ignition and Growth reactive flow model for Composition B is extended to yield accurate simulations of this new threshold velocity data for various flyer thicknesses.

Microgravity mediated changes in phytoferritin accumulation in soybean root cap cells

NASA Technical Reports Server (NTRS)

Klymchuk, D. O.; Kordyum, E. L.; Vorobyova, T. V.; Brown, C. S.; Chapman, D. K.

2000-01-01

Phytoferritin is an iron-protein complex analogous to the ferritin found in mammalian, bacteria and fungi cells. Phytoferritin molecules are large proteins, about 10.5 nm in diameter, visualised in an electron microscope as discrete, electron dense particles with iron-containing core, where several thousand atoms of iron lie within the proteinaceous shell (apoferritin). In higher plants, a plastid stroma is the site of phytoferritin storage. Phytoferritin is seen in all types of plastids. It is considered to be a mechanism used by cells to store iron in a non-toxic form. Phytoferritin-bound iron may subsequently be used to form iron-containing components. It was shown that low levels of phytoferritin are synthesised in normal green leaves, whereas chlorotic leaves do not have a measurable amount of phytoferritin and leaves of iron-loaded seedlings contain a high level of total iron, and phytoferritin well-filled by iron. Phytoferritin accumulation was observed in photosynthetic inactivity chloroplasts during senescence and disease. In this study we analised the effects of microgravity and ethylene on production of phytoferritin in the root cap columella cells of soybean seedlings.

Effects of ambient ozone on first-year growth and physiology of black cherry (Prunus serotina Ehrh. ) seedlings

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

Kolb, T.E.; Skelly, J.M.; Steiner, K.C.

1993-06-01

Black cherry seedlings of two open-pollinated families were exposed to ambient ozone in open plots (100%) and plots receiving non-filtered (95%), half-filtered (60%) and full-filtered (40%) concentrations via open-top chambers between early June and late-September 1992 in a replicated field experiment in central Pennsylvania. Seasonal 24-hour ambient ozone concentration averaged 34 ppb with a peak 1-hour concentration of 110 ppb. Foliar symptoms of ozone damage (adaxial stipple) occurred most prominently in open and non-filtered plots and differed between families. Net photosynthetic rate for both families was significantly lower in open and non-filtered plots compared with half- and full-filtered plots onmore » most dates, while ozone concentration had no consistent effect on leaf conductance or dark respiration. Leaf conductance of the ozone sensitive family was significantly greater than the ozone tolerant family on most dates. First-year height and diameter growth were significantly lower in open and non-filtered plots compared with half- and full-filtered plots for both families.« less

Induced polyploidization in Brassica campestris L. (Brassicaceae).

PubMed

Kumar, G; Dwivedi, K

2014-01-01

Present experimental design has been made up to obtain crop with higher ploidy level via synthetic polyploidization. Since ploidy manipulation is generally associated with the obtainment of some increased enviable traits of the crop and also provides them greater adaptability to unfavorable or harsh circumstances as compared to its diploids counterparts. Thus, herein present research autotetraploids of Brassica campestris L. have been lucratively achieved by the application of colchicine. Two methods of treatment were utilized i.e. seed treatment and seedling treatment. No polyploidy could be obtained through seed treatment while seedling treatment responded well towards polyploidy. However, the status of autotetraploidy has been confirmed by cytomorphological investigations of treated plants as against its diploids counterparts. For the purpose, morphological parameters such as increased stomata size, pollen diameter, flower size, reproductive organs whereas reduction in plant height, leaf length, leaf breadth, stomata frequency, number of flowers/inflorescence etc. were appraised. Further, cytological observations were made that had clearly revealed the doubling of genome in the autotetraploids as compared to diploids. Meanwhile, pollen fertility and size of pollen grains were evaluated as well.

Chronic drought stress reduced but not protected Shantung maple (Acer truncatum Bunge) from adverse effects of ozone (O3) on growth and physiology in the suburb of Beijing, China.

PubMed

Li, Li; Manning, William J; Tong, Lei; Wang, Xiaoke

2015-06-01

A two-year experiment exposing Acer truncatum Bunge seedlings to elevated ozone (O3) concentrations above ambient air (AO) and drought stress (DS) was carried out using open-top chambers (OTCs) in a suburb of Beijing in north China in 2012-2013. The results suggested that AO and DS had both significantly reduced leaf mass area (LMA), stomatal conductance (Gs), light saturated photosynthetic rate (Asat) as well as above and below ground biomass at the end of the experiment. It appeared that while drought stress mitigated the expression of foliar injury, LMA, leaf photosynthetic pigments, height growth and basal diameter, due to limited carbon fixation, the O3 - induced reductions in Asat, Gs and total biomass were enhanced 23.7%. 15.5% and 8.1% respectively. These data suggest that when the whole plant was considered that drought under the conditions of this experiment did not protect the Shantung maple seedlings from the effects of O3. Copyright © 2015 Elsevier Ltd. All rights reserved.

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...

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.

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

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.

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

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

Detonation re-initiation in a concentric tube arrangement for C_2H_2/O_2/Ar mixtures

NASA Astrophysics Data System (ADS)

Wu, Y.; Lee, J. H. S.; Weng, C.

2017-05-01

Re-initiation of detonation in a concentric tube arrangement where a detonation exiting from a small diameter inner tube to a large diameter outer tube has been investigated. The outer tube diameter D is 50.8 mm and inner tube diameters d are 38, 25.4, and 12.7 mm giving diameter ratios D/d=1.34, 2, and 4. Stoichiometric C_2H_2-O_2 mixtures with argon dilution of 0, 25, 50, and 70% are used in the present study. Velocity measurements are made using photodiodes, and smoked foils downstream of the exit of the inner tube are also used to record the re-initiation process. Upon exit from the inner tube, the detonation suffers an abrupt decrease in velocity and at critical conditions, the velocity downstream of the exit is of the order of 50% of the Chapman-Jouguet velocity. It is found that re-initiation generally occurs within 10 tube diameters downstream of the exit. If re-initiation is not successful, the detonation continues to propagate at a low velocity for distances of the order of 30 tube diameters without any indication of flame acceleration of deflagration-to-detonation transition (DDT). Thus, the re-initiation process is clearly defined and distinct from the usual DDT in a smooth tube. The critical d/λ value ratio in the concentric tube is significantly lower than the usual unconfined case of d/λ =13 where λ is the detonation cell size. Thus, it is a result of re-initiation at the Mach stem of the reflected shock from the wall of the outer concentric tube. If re-initiation is not successful upon the first reflection, then subsequent multiple reflections at the tube axis and wall of the outer tube can also result in re-initiation. However, this is only observed for undiluted mixtures. For high-argon-diluted mixtures, re-initiation only occurs at the Mach stem of the first reflection.

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.

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.

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

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.

The national Fire and Fire Surrogate study: Effects of fuel reduction methods on forest vegetation structure and fuels

USGS Publications Warehouse

Schwilk, D.W.; Keeley, J.E.; Knapp, E.E.; Mciver, J.; Bailey, J. D.; Fettig, C.J.; Fiedler, C.E.; Harrod, R.J.; Moghaddas, J.J.; Outcalt, K.W.; Skinner, C.N.; Stephens, S.L.; Waldrop, T.A.; Yaussy, D.A.; Youngblood, A.

2009-01-01

Changes in vegetation and fuels were evaluated from measurements taken before and after fuel reduction treatments (prescribed fire, mechanical treatments, and the combination of the two) at 12 Fire and Fire Surrogate (FFS) sites located in forests with a surface fire regime across the conterminous United States. To test the relative effectiveness of fuel reduction treatments and their effect on ecological parameters we used an informationtheoretic approach on a suite of 12 variables representing the overstory (basal area and live tree, sapling, and snag density), the understory (seedling density, shrub cover, and native and alien herbaceous species richness), and the most relevant fuel parameters for wildfire damage (height to live crown, total fuel bed mass, forest floor mass, and woody fuel mass). In the short term (one year after treatment), mechanical treatments were more effective at reducing overstory tree density and basal area and at increasing quadratic mean tree diameter. Prescribed fire treatments were more effective at creating snags, killing seedlings, elevating height to live crown, and reducing surface woody fuels. Overall, the response to fuel reduction treatments of the ecological variables presented in this paper was generally maximized by the combined mechanical plus burning treatment. If the management goal is to quickly produce stands with fewer and larger diameter trees, less surface fuel mass, and greater herbaceous species richness, the combined treatment gave the most desirable results. However, because mechanical plus burning treatments also favored alien species invasion at some sites, monitoring and control need to be part of the prescription when using this treatment. ?? 2009 by the Ecological Society of America.

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.

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.

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.

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 effects of planting methods and head pruning on seed yield and yield components of medicinal pumpkin (Cucurbita pepo subsp. Pepo convar. Pepo var. styriaca) at low temperature areas.

PubMed

Bahrami, R Nikkhah; Khodadadi, M; Pirivatlo, S Piry; Hassanpanah, D

2009-03-15

This experiment carried out to evaluate the effects of planting methods (seed sowing and transplanting) and head pruning (no pruning, pruning after 12th node and pruning after 16th node) on yield and yield components such as number of branches (sub-branches) per plant, fruits per plant, growth, fruit size, weight of fresh fruit, weight of seeds per fruit, number of seeds per fruit and seed yield of medicinal pumpkin. The experiment was carried out based of factorial experiment with Randomized Completely Blocks Design (RCBD) by three replications in Ardabil Agricultural and Natural Resources Researches Station at 2007. Seedlings were grown in heated greenhouse. When the climatic condition became suitable and seedlings were at the four leaves stage, both seeds and seedlings were planted at the same time in the farm. Maintenance operations were done during the growth season. Head pruning treatments were done the forecast time. The results showed that the planting methods had significant effect on the number of ripen fruits per plant, fruits diameter, weight of seeds per fruit, weight of 1000 seeds and seed yield and had no significant effect on the other traits. Also the results indicated that head pruning treatments had significant effects on the number of branches per plant, growth and seed yield and no significant on the other traits. In this experiment the most seed yield (997.8 kg ha(-1)) obtained from transplanting method with head pruning after 12th node and the least seed yield obtained from control.

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.

Effects of control parameters of three-point initiation on the formation of an explosively formed projectile with fins

NASA Astrophysics Data System (ADS)

Li, R.; Li, W. B.; Wang, X. M.; Li, W. B.

2018-03-01

The effects of the initiation diameter and synchronicity error on the formation of fins and stable-flight velocity of an explosively formed projectile (EFP) with three-point initiation are investigated. The pressure and area of the Mach wave acting on the metal liner at different initiation diameters are calculated employing the Whitham method. LS-DYNA software is used to investigate the asymmetric collision of detonation waves resulting from three-point initiation synchronicity error, the distortion characteristics of the liner resulting from the composite detonation waves, and the performance parameters of the EFP with fins. Results indicate that deviations of the Y-shaped high-pressure zone and central ultrahigh-pressure zone from the liner center can be attributed to the error of three-point initiation, which leads to the irregular formation of EFP fins. It is noted that the area of the Mach wave decreases, but the pressure of the Mach wave and the final speed and length-to-diameter ( L/ D) ratio of the EFP increase, benefiting the formation of the EFP fins, as the initiation diameter increases.

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

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.

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

Root-type-specific plasticity in response to localized high nitrate supply in maize (Zea mays)

PubMed Central

Yu, Peng; Hochholdinger, Frank; Li, Chunjian

2015-01-01

Background and Aims Shoot-borne roots contribute to most of the nutrient uptake throughout the life cycle of maize (Zea mays). Compared with numerous studies with embryonic roots, detailed information on the phenotypic plasticity of shoot-borne roots in response to a heterogeneous nitrogen supply is scarce. The present study therefore provides a comprehensive profile of fine-scale plastic responses of distinct root types to localized high nitrate supply. Methods Seedlings of the maize inbred line B73 were grown in split-root systems. The anatomy and morphological plasticity of the primary root and the roots initiated from the 2nd, 5th and 7th shoot nodes, and their lateral roots, were studied in response to local high nitrate supply to one side of the root system. Key Results In contrast to the insensitivity of axial roots, local high nitrate supply increased the length of 1st-order lateral roots on the primary root and the three whorls of shoot-borne roots at different growth stages, and increased the density of 1st-order lateral roots on the 7th shoot-borne root after silking. The length and density of 2nd-order lateral roots on the three whorls of shoot-borne roots displayed a more flexible response to local high nitrate than 1st-order lateral roots. Root diameter and number, and total area and diameter of metaxylem vessels increased from the primary root to early and then later developed shoot-borne roots, which showed a positive relationship with shoot growth and N accumulation. Conclusions Maize axial roots and lateral roots responded differently to local high nitrate, and this was related to their function. The extent of morphological plasticity of lateral roots in response to local high nitrate depended on the initiation time of the shoot-borne roots on which the lateral roots developed. Morphological plasticity was higher on 2nd-order than on 1st-order lateral roots. The results suggest that higher order lateral root branching might be a potential target for genetic improvement in future maize breeding. PMID:26346717

Diameter Effect In Initiating Explosives, Numerical Simulations

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

Lefrancois, A.; Benterou, J.; Roeske, F.

2006-02-10

The ability to safely machine small pieces of HE with the femtosecond laser allows diameter effect experiments to be performed in initiating explosives in order to study the failure diameter, the reduction of the detonation velocity and curvature versus the diameter. The reduced diameter configuration needs to be optimized, so that the detonation products of the first cylinder will not affect the measurement of the detonation velocity of the second cylinder with a streak camera. Different 2D axi-symmetrical configurations have been calculated to identify the best solution using the Ignition and Growth reactive flow model for LX16 Pellet with Ls-Dyna.

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

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.

ESA hardware for plant research on the International Space Station

NASA Astrophysics Data System (ADS)

Brinckmann, E.

The long awaited launch of the European Modular Cultivation System (EMCS) will provide a platform on which long-term and shorter experiments with plants will be performed on the International Space Station (ISS). EMCS is equipped with two centrifuge rotors (600 mm diameter), which can be used for in-flight 1 g controls and for studies with acceleration levels from 0.001 g to 2.0 g. Several experiments are in preparation investigating gravity relating to gene expression, gravisensing and phototropism of Arabidopsis thaliana and lentil roots. The experiment-specific hardware provides growth chambers for seedlings and whole A. thaliana plants and is connected to the EMCS Life Support System. Besides in-flight video observation, the experiments will be evaluated post-flight by means of fixed or frozen material. EMCS will have for the first time the possibility to fix samples on the rotating centrifuge, allowing a detailed analysis of the process of gravisensing. About two years after the EMCS launch, ESA's Biolab will be launched in the European "Columbus" Module. In a similar way as in EMCS, Biolab will accommodate experiments with plant seedlings and automatic fixation processes on the centrifuge. The hardware concepts for these experiments are presented in this communication.

New Developments in Spaceflight Hardware for Plant Research

NASA Astrophysics Data System (ADS)

Brinckmann, E.

The long awaited launch of the European Modular Cultivation System (EMCS) will provide a platform to perform long term and shorter experiments with plants on the International Space Station (ISS). EMCS is equipped with two centrifuge rotors (600 mm diameter), which can be used for flight 1xg controls and for studies with accelerations from 0.001xg to 2.0xg. Several experiments are in preparation, investigating gravity related gene expressions, gravisensing and phototropism of Arabidopsis thaliana, fern spores and lentil rots. The experiment specific hardware provides growth chambers for seedlings and whole A. thaliana plants, connected to the EMCS Life Support System. Besides video observation, the experiments will be evaluated on ground by means of fixed or frozen material. EMCS will have for the first time the possibility to fix samples on the rotating centrifuge, allowing a detailed analysis of the process of gravisensing. Two years after EMCS, ESA's BIOLAB will be launched in the European "Columbus" Module. In a similar way as in EMCS, BIOLAB accommodates experiments with plant seedlings and automatic fixation processes on the centrifuge. The hardware concepts for these experiments will be presented in this communication.

Analysis of vegetation changes in Rock Creek Park, 1991-2007

USGS Publications Warehouse

Hatfield, Jeff S.; Krafft, Cairn

2009-01-01

Vegetation data collected at Rock Creek Park every 4 years during 1991-2007 were analyzed for differences among 3 regions within the park and among years. The variables measured and analyzed were percentage of twigs browsed, percentage of canopy cover, species richness of herbaceous plants, number of tree seedlings in each of 7 height classes, tree seedling stocking rate for low deer density and high deer density areas, percentage of tree and shrub cover < 2 m in height, mean diameter at breast height (DBH) of trees > 1 cm DBH, number of tree stems > 1 cm DBH, species richness of trees and shrubs, and mean height of the 5 tallest trees in each plot quadrant. Repeated measures analysis of variance (ANOVA) was used to test for differences and, except for some differences in tree species composition among the 3 regions, no differences (P > 0.01) were found among the 3 regions in the variables discussed above. Many of the variables showed very significant differences (P < 0.01) among years, and causative factors should be investigated further. In addition, importance values were calculated for the 10 most important tree species in each region and changes over time were reported. Future sampling recommendations are also discussed.

Floristic evolution in an agroforestry system cultivation in Southern Brazil.

PubMed

Silva, Luís C R; Machado, Sebastião A; Galvão, Franklin; Figueiredo, Afonso

2016-06-07

Bracatinga (Mimosa scabrella Bentham) is an important pioneer tree species in Ombrophylous Mixed Forest of Brazil and is widely used as an energy source. In traditional agroforestry systems, regeneration is induced by fire, then pure and dense stands known as bracatinga stands (bracatingais) are formed. In the first year, annual crops are intercalated with the seedlings. At that time the seedlings are thinned, then the stands remain at a fallow period and cut at seven years old. The species is very important mainly for small landowners. We studied the understory species that occur naturally during the succession over several years in order to manage them rationally in the future and maintain the natural vegetation over time. Three to 20 year-old Bracatinga stands were sampled between 1998 and 2011. All tree species with diameter at breast height (DBH) ≥ 5 cm were measured.The floristic evolution was assessed with respect to Sociability Index, the Shannon Diversity Index and the Pielou Evenness Index. Graphs of rank/abundance over different age groups were evaluated using the Kolmogorov-Smirnov test. We identified 153 species dispersed throughout the understory and tend to become aggregated over time.

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 ...

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...

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...

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....

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.

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 initial soil properties on six-year growth of 15 tree species in tropical restoration plantings.

PubMed

Martínez-Garza, Cristina; Campo, Julio; Ricker, Martin; Tobón, Wolke

2016-12-01

In restoration plantings in degraded pastures, initial soil nutrient status may lead to differential growth of tropical tree species with diverse life history attributes and capacity for N 2 fixation. In 2006, we planted 1,440 seedlings of 15 native tree species in 16 fenced plots (30 × 30 m) in a 60-year-old pasture in Los Tuxtlas, Veracruz, Mexico, in two planting combinations. In the first year, we evaluated bulk density, pH, the concentration of organic carbon (C), total nitrogen (N), ammonia (NO3-), nitrate (NH4+), and total phosphorus (P) in the upper soil profile (0-20 cm in depth) of all plots. The first two axes of two principal component analyses explained more than 60% of the variation in soil variables: The axes were related to increasing bulk density, NO3-, NH4+, total N concentration, and pH. Average relative growth rates in diameter at the stem base of the juvenile trees after 6 years were higher for pioneer (45.7%) and N 2 -fixing species (47.6%) than for nonpioneer (34.7%) and nonfixing species (36.2%). Most N 2 -fixing species and those with the slowest growth rates did not respond to soil attributes. Tree species benefited from higher pH levels and existing litter biomass. The pioneers Ficus yoponensis , Cecropia obtusifolia , and Heliocarpus appendiculatus , and the N 2 -fixing nonpioneers Cojoba arborea , Inga sinacae , and Platymiscium dimorphandrum were promising for forest restoration on our site, given their high growth rates.

Combustion of a Polymer (PMMA) Sphere in Microgravity

NASA Technical Reports Server (NTRS)

Yang, Jiann C.; Hamins, Anthony; Donnelly, Michelle K.

1999-01-01

A series of low gravity, aircraft-based, experiments was conducted to investigate the combustion of supported thermoplastic polymer spheres under varying ambient conditions. The three types of thermoplastic investigated were polymethylmethacrylate (PMMA), polypropylene (PP). and polystyrene (PS). Spheres with diameters ranging from 2 mm to 6.35 mm were tested. The total initial pressure varied from 0.05 MPa to 0. 15 MPa whereas the ambient oxygen concentration varied from 19 % to 30 % (by volume). The ignition system consisted of a pair of retractable energized coils. Two CCD cameras recorded the burning histories of the spheres. The video sequences revealed a number of dynamic events including bubbling and sputtering, as well as soot shell formation and break-up during combustion of the spheres at reduced gravity. The ejection of combusting material from the burning spheres represents a fire hazard that must be considered at reduced gravity. The ejection process was found to be sensitive to polymer type. All average burning rates were measured to increase with initial sphere diameter and oxygen concentration, whereas the initial pressure had little effect. The three thermoplastic types exhibited different burning characteristics. For the same initial conditions, the burning rate of PP was slower than PMMA, whereas the burning rate of PS was comparable to PMMA. The transient diameter of the burning thermoplastic exhibited two distinct periods: an initial period (enduring approximately half of the total burn duration) when the diameter remained approximately constant, and a final period when the square of the diameter linearly decreased with time. A simple homogeneous two-phase model was developed to understand the changing diameter of the burning sphere. Its value is based on a competition between diameter reduction due to mass loss from burning and sputtering, and diameter expansion due to the processes of swelling (density decrease with heating) and bubble growth. The model relies on empirical parameters for input, such as the burning rate and the duration of the initial and final burning periods.

Integrating Residual Stress Analysis of Critical Fastener Holes into USAF Depot Maintenance

DTIC Science & Technology

2014-11-02

40 Table 15. Metrology of the initial reamer, initial hole diameters, and resulting CX for the class/type hole combinations for Pattern 1...70 Table 16. Metrology of the initial reamer, initial hole diameters, and resulting...step in the cold work process. These procedures produce a digital documentation of the hole, based on critical metrology , which can be linked with

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.

Membranous appendices of spherosomes (oleosomes) : Possible role in fat utilization in germinating oil seeds.

PubMed

Wanner, G; Theimer, R R

1978-01-01

Spherosomes (oleosomes) of cotyledons of rape (Brassica napus L.), sunflower (Helianthus annuus L.), and watermelon (Citrullus vulgaris, Schrad.) seedlings are delimited by a "half unit membrane" that appears to be continuous with each of the osmiophilic layers of a tripartite unit membrane forming a handlelike appendix of the spherosomes. Prior to any noticeable utilization of the spherosomal storage fat, ribosomes were found to be attached to these "handles". At later stages appendices of the spherosomes are smooth, showing a diameter of about 22 nm that greatly exceeds the thickness of any other unit membrane profiles identical in structure and diameter osomes appears to be continuous with the thick lipid layer of the handles. In intermediate stages of fat depletion the spherosomal bodies become invaginated with cytoplasmic material. Finally vesicles with cytoplasmic contents surrounded by a membrane with a typically thick lipid layer are left in the cells. Membrane profiles indentical in structure and diameter to the spherosomal appendices were also present in electron micrographs of the lipolytic membrane fraction recovered from sucrose density gradients after centrifugation of a microsomal cell fraction. The ultrastructural observations are taken for evidence that the spherosomal appendices represent the lipase-carrying membranes isolated previously (Theimer and Rosnitschek, 1978). A novel hypothesis for development and utilization of fat-storing spherosomes is also proposed.

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...

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.

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...

Methanol Droplet Extinction in Carbon-Dioxide-Enriched Environments in Microgravity

NASA Technical Reports Server (NTRS)

Hicks, Michael C.; Nayagam, Vedha; Williams, Forman A.

2010-01-01

Diffusive extinction of methanol droplets with initial diameters between 1.25 mm and 1.72 mm, burning in a quiescent microgravity environment at one atmosphere pressure, was obtained experimentally for varying levels of ambient carbon-dioxide concentrations with a fixed oxygen concentration of 21% and a balance of nitrogen. These experiments serve as precursors to those which are beginning to be performed on the International Space Station and are motivated by the need to understand the effectiveness of carbon-dioxide as a fire suppressant in low-gravity environments. In these experiments, the flame standoff distance, droplet diameter, and flame radiation are measured as functions of time. The results show that the droplet extinction diameter depends on both the initial droplet diameter and the ambient concentration of carbon dioxide. Increasing the initial droplet diameter leads to an increased extinction diameter, while increasing the carbon-dioxide concentration leads to a slight decrease in the extinction diameter. These results are interpreted using a critical Damk hler number for extinction as predicted by an earlier theory, which is extended here to be applicable in the presence of effects of heat conduction along the droplet support fibers and of the volume occupied by the support beads

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...

Light requirements of Australian tropical vs. cool-temperate rainforest tree species show different relationships with seedling growth and functional traits.

PubMed

Lusk, Christopher H; Kelly, Jeff W G; Gleason, Sean M

2013-03-01

A trade-off between shade tolerance and growth in high light is thought to underlie the temporal dynamics of humid forests. On the other hand, it has been suggested that tree species sorting on temperature gradients involves a trade-off between growth rate and cold resistance. Little is known about how these two major trade-offs interact. Seedlings of Australian tropical and cool-temperate rainforest trees were grown in glasshouse environments to compare growth versus shade-tolerance trade-offs in these two assemblages. Biomass distribution, photosynthetic capacity and vessel diameters were measured in order to examine the functional correlates of species differences in light requirements and growth rate. Species light requirements were assessed by field estimation of the light compensation point for stem growth. Light-demanding and shade-tolerant tropical species differed markedly in relative growth rates (RGR), but this trend was less evident among temperate species. This pattern was paralleled by biomass distribution data: specific leaf area (SLA) and leaf area ratio (LAR) of tropical species were significantly positively correlated with compensation points, but not those of cool-temperate species. The relatively slow growth and small SLA and LAR of Tasmanian light-demanders were associated with narrow vessels and low potential sapwood conductivity. The conservative xylem traits, small LAR and modest RGR of Tasmanian light-demanders are consistent with selection for resistance to freeze-thaw embolism, at the expense of growth rate. Whereas competition for light favours rapid growth in light-demanding trees native to environments with warm, frost-free growing seasons, frost resistance may be an equally important determinant of the fitness of light-demanders in cool-temperate rainforest, as seedlings establishing in large openings are exposed to sub-zero temperatures that can occur throughout most of the year.

Application of neem (Azadirachta indica) as biological pesticides in cocoa seed (Theobroma cacao) storage using various local adsorbent media

NASA Astrophysics Data System (ADS)

Mardiyani, S. A.; Sunawan; Pawestri, A. E.

2018-03-01

Cocoa seeds are recalcitrant (the water content is more than 40%) that require special handling. The use of adsorbent media to reduce the decrease in the quality of cocoa seeds and extend their shelf life in this storage has not been widely done. Local adsorbent media such as sawdust, sand and ash have the potential to maintain the viability of cocoa seeds. The objective of this research was to determine the interaction of the application of neem (Azadirachta indica) as biological pesticides and the use of various natural adsorbent media in the storage of cocoa seeds (Theobroma cacao). It was an experimental study with a factorial design composed of three factors. The first factor was the medium adsorbent type for the storage of cocoa seed, which consists of three levels (river sand, ash, and sawdust). The second factor was the concentration of neem leaves for pre-storage treatment with three levels (10, 20, and 30%). The third factor was the storage time (10 and 20 days). The results of the study indicated that the combination of the three factors showed a significant interaction in the height of the plant and the diameter of the stem of the seedling at 28 days after sowing. The fresh weight of the seedlings of the seeds that were stored in ash media gave a better result than the seedlings of seeds that had been stored in the river sand and the sawdust as adsorbent media. The application of 20% extract of neem leaves gave the best influence for the seeds that were stored for 20 days.

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.

Origin of sigmoid diameter distributions

Treesearch

William B. Leak

2002-01-01

Diameter distributions--numbers of trees over diameter at breast height (d.b.h.)--were simulated over 20-years using six diameter-growth schedules, six mortality trends, and three initial conditions. The purpose was to determine factors responsible for the short-term development of the arithmetic rotated sigmoid form of diameter distribution characterized by a plateau...

Tetraploidy enhances the ability to exclude chloride from leaves in carrizo citrange seedlings.

PubMed

Ruiz, M; Quiñones, A; Martínez-Cuenca, M R; Aleza, P; Morillon, R; Navarro, L; Primo-Millo, E; Martínez-Alcántara, B

2016-10-20

Tetraploid citrus seedlings are more tolerant to salt stress than diploid genotypes. To provide insight into the causes of differences in salt tolerance due to ploidy and thus to better understand Cl - exclusion mechanisms in citrus, diploid and tetraploid seedlings of Carrizo citrange (CC) were grown at 0 (control) and 40mM NaCl (salt-treated) medium for 20 days. Chloride uptake and root-to-shoot translocation rates were on average 1.4-fold higher in diploid than in tetraploid salt-treated plants, which resulted in a greater (1.6-fold) Cl - build up in the leaves of the former. Root hydraulic conductance and leaf transpiration rate were 58% and 17% lower, respectively, in tetraploid than in diploid control plants. Differences remained after salt treatment which reduced these parameters by 30-40% in both genotypes. Morphology of the root system was significantly influenced by ploidy. Tetraploid roots were less branched and with lower number of root tips than those of diploid plants. The cross-section diameter and area were lower in the diploid, and consequently specific root length was higher (1.7-fold) than in tetraploid plants. The exodermis in sections close to the root apex was broader and with higher deposition of suberin in cell walls in the tetraploid than in the diploid genotype. Net CO 2 assimilation rate in tetraploid salt-treated seedlings was 1.5-fold higher than in diploid salt-treated plants, likely due to the loss of photosynthetic capacity of diploid plants induced by Cl - toxicity. Leaf damage was much higher, in terms of burnt area and defoliation, in diploid than in tetraploid salt-treated plants (8- and 6-fold, respectively). Salt treatment significantly reduced (37%) the dry weight of the diploid plants, but did not affect the tetraploids. In conclusion, tetraploid CC plants appear more tolerant to salinization and this effect seems mainly due to differences in morphological and histological traits of roots affecting hydraulic conductance and transpiration rate. These results may suggest that tetraploid CC used as rootstock could improve salt tolerance in citrus trees. Copyright © 2016 Elsevier GmbH. All rights reserved.

How does tree age influence damage and recovery in forests impacted by freezing rain and snow?

PubMed

Zhu, LiRong; Zhou, Ting; Chen, BaoMing; Peng, ShaoLin

2015-05-01

The response and recovery mechanisms of forests to damage from freezing rain and snow events are a key topic in forest research and management. However, the relationship between the degree of damage and tree age, i.e., whether seedlings, young trees, or adult trees are most vulnerable, remains unclear and is rarely reported. We investigated the effect of tree age on the degrees of vegetation damage and subsequent recovery in three subtropical forest types-coniferous, mixed, and broad-leaved-in the Tianjing Mountains, South China, after a series of rare icy rain and freezing snow events in 2008. The results showed that damage and recovery rates were both dependent on tree age, with the proportion of damaged vegetation increasing with age (estimated by diameter at breast height, DBH) in all three forest types and gradually plateauing. Significant variation occurred among forest types. Young trees in the coniferous forest were more vulnerable than those in the broad-leaved forest. The type of damage also varied with tree age in different ways in the three forest types. The proportion of young seedlings that were uprooted (the most severe type of damage) was highest in the coniferous forest. In the mixed forest, young trees were significantly more likely to be uprooted than seedlings and adult trees, while in the broad-leaved forest, the proportion of uprooted adult trees was significantly higher than that of seedlings and young trees. There were also differences among forest types in how tree age affected damage recovery. In the coniferous forest, the recovery rate of trees with broken trunks or crowns (DBH > 2.5 cm) increased with tree age. However, in the mixed and broad-leaved forests, no obvious correlation between the recovery rate of trees with broken trunks or crowns and tree age was observed. Trees with severe root damage did not recover; they were uprooted and died. In these forests, vegetation damage and recovery showed tree age dependencies, which varied with tree shape, forest type, and damage type. Understanding this dependency will guide restoration after freezing rain and snow disturbances.

[Interspecific allelopathic effect of different organs' aqueous extracts of Betula platyphylla and Larix olgensis on their seed germination and seedling growth].

PubMed

Liu, Zhong-Ling; Wang, Qing-Cheng; Hao, Long-Fei

2011-12-01

In this paper, the Betula platyphylla root-, branch-, and foliage aqueous extracts and Larix olgensis root-, branch-, foliage-, and bark aqueous extracts over a range of concentrations 5.0, 12.5, 25.0, 50.0, and 100.0 mg x mL(-1) were used to study their interspecific allelopathic effect on the seed germination and seedling growth of the two tree species. All the L. olgensis organs' extracts, except its root extracts at concentration 5.0 mg x mL(-1), had inhibition effect on B. platyphylla seed germination rate, which was 54%, 58%, 59%, and 66% under the effects of L. olgensis foliage-, branch-, bark-, and root extracts, respectively, as compared with the control. With increasing concentration, the inhibition effect of L. olgensis root- and branch extracts increased while that of L. olgensis foliage- and bark extracts decreased. The L. olgensis organs' extracts, especially the foliage extracts at concentration 100.0 mg x mL(-1), had strong inhibition effect on B. platyphylla seed radicle- and hypocotyl length growth, with a decrement of 38% and 55% (P < 0.05), respectively. L. olgensis branch- and foliage extracts promoted, but root- and bark extracts inhibited B. platyphylla seedling growth and biomass production. B. platyphylla organs' extracts promoted L. olgensis seed germination, root- and branch extracts promoted hypocotyl length growth, but foliage extracts at 50.0 and 100.0 mg x mL(-1) decreased the hypocotyl length growth by 27% and 28% (P < 0.05), respectively. B. platyphylla organs' extracts mainly promoted L. olgensis seedling growth, with the height- and collar diameter growth and biomass accumulation at B. platyphylla foliage extracts concentration 5.0 mg x mL(-1) increased by 54%, 60%, and 100% (P < 0.05), respectively. Our results suggested that there existed obvious allelopathic effect between B. platyphylla and L. olgensis, and thus, mixed planting B. platyphylla and L. olgensis could have promotion effects on the growth of the two tree species.

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

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.

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.

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.

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.

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...

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...

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...

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...

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...

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.

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...

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.

Effect of off-season flooding on growth, photosynthesis, carbohydrate partitioning, and nutrient uptake in Distylium chinense.

PubMed

Liu, Zebin; Cheng, Ruimei; Xiao, Wenfa; Guo, Quanshui; Wang, Na

2014-01-01

Distylium chinense is an evergreen shrub used for the vegetation recovery of floodplain and riparian areas in Three Gorges Reservoir Region. To clarify the morphological and physiological responses and tolerance of Distylium chinense to off-season flooding, a simulation flooding experiment was conducted during autumn and winter. Results indicated that the survival rate of seedlings was 100%, and that plant height and stem diameter were not significantly affected by flooding. Adventitious roots and hypertrophic lenticels were observed in flooded seedlings after 30 days of flooding. Flooding significantly reduced the plant biomass of roots, net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), maximum photochemical efficiency (Fv/Fm), photochemical quenching (qP), and electron transport rate (ETR) in leaves, and also affected the allocation and transport of carbohydrate and nutrients. However, D. chinense was able to maintain stable levels of Pn, Fv/Fm, qP, ETR, and nutrient content (N and P) in leaves and to store a certain amount of carbohydrate in roots over prolonged durations of flooding. Based on these results, we conclude that there is a high flooding tolerance in D. chinense, and the high survival rate of D. chinense may be attributable to a combination of morphological and physiological responses to flooding.

Phosphorous fertilization alleviates drought effects on Alnus cremastogyne by regulating its antioxidant and osmotic potential.

PubMed

Tariq, Akash; Pan, Kaiwen; Olatunji, Olusanya Abiodun; Graciano, Corina; Li, Zilong; Sun, Feng; Zhang, Lin; Wu, Xiaogang; Chen, Wenkai; Song, Dagang; Huang, Dan; Xue, Tan; Zhang, Aiping

2018-04-04

Alnus cremastogyne, a broad-leaved tree endemic to south-western China, has both commercial and restoration importance. However, little is known of its morphological, physiological and biochemical responses to drought and phosphorous (P) application. A randomized experimental design was used to investigate how drought affected A. cremastogyne seedlings, and the role that P applications play in these responses. Drought had significant negative effects on A. cremastogyne growth and metabolism, as revealed by reduced biomass (leaf, shoot and root), leaf area, stem diameter, plant height, photosynthetic rate, leaf relative water content, and photosynthetic pigments, and a weakened antioxidative defence mechanism and high lipid peroxidation level. However, the reduced leaf area and enhanced osmolyte (proline and soluble sugars) accumulation suggests drought avoidance and tolerance strategies in this tree. Applying P significantly improved the leaf relative water content and photosynthetic rate of drought-stressed seedlings, which may reflect increased anti-oxidative enzyme (superoxide dismutase, catalase and peroxidase) activities, osmolyte accumulation, soluble proteins, and decreased lipid peroxidation levels. However, P had only a slight or negligible effect on the well-watered plants. A. cremastogyne is sensitive to drought stress, but P facilitates and improves its metabolism primarily via biochemical and physiological rather than morphological adjustments, regardless of water availability.

Mutation of a chitinase-like gene causes ectopic deposition of lignin, aberrant cell shapes, and overproduction of ethylene.

PubMed

Zhong, Ruiqin; Kays, Stanley J; Schroeder, Betty P; Ye, Zheng-Hua

2002-01-01

Chitinase-like proteins have long been proposed to play roles in normal plant growth and development, but no mutations in chitinase-like genes have been obtained previously to support this hypothesis. In this study, we have shown that the gene responsible for the elp1 mutation in Arabidopsis encodes a chitinase-like protein (AtCTL1). Mutation of this chitinase-like gene caused ectopic deposition of lignin and aberrant shapes of cells with incomplete cell walls in the pith of inflorescence stems. The AtCTL1 gene was expressed in all organs during normal plant growth and development, but it was not induced by wounding, salicylic acid, pectin fragments, or ethylene. Consistent with its ubiquitous expression pattern, mutation of the AtCTL1 gene affected many aspects of plant growth and development, including exaggerated hook curvature, reduced length and increased diameter of hypocotyls in dark-grown seedlings, and reduced root length and increased number of root hairs in light-grown seedlings. The mutant phenotypes could be rescued partially by ethylene inhibitors, and ethylene production in the mutant was significantly greater than in the wild type. Together, these results suggest that AtCTL1, a chitinase-like gene, is essential for normal plant growth and development in Arabidopsis.

Roots Revealed - Neutron imaging insight of spatial distribution, morphology, growth and function

NASA Astrophysics Data System (ADS)

Warren, J.; Bilheux, H.; Kang, M.; Voisin, S.; Cheng, C.; Horita, J.; Perfect, E.

2013-05-01

Root production, distribution and turnover are not easily measured, yet their dynamics are an essential part of understanding and modeling ecosystem response to changing environmental conditions. Root age, order, morphology and mycorrhizal associations all regulate root uptake of water and nutrients, which along with along with root distribution determines plant response to, and impact on its local environment. Our objectives were to demonstrate the ability to non-invasively monitor fine root distribution, root growth and root functionality in Zea mays L. (maize) and Panicum virgatum L. (switchgrass) seedlings using neutron imaging. Plants were propagated in aluminum chambers containing sand then placed into a high flux cold neutron beam line. Dynamics of root distribution and growth were assessed by collecting consecutive CCD radiographs through time. Root functionality was assessed by tracking individual root uptake of water (H2O) or deuterium oxide (D2O) through time. Since neutrons strongly scatter H atoms, but not D atoms, biological materials such as plants are prime candidates for neutron imaging. 2D and 3D neutron radiography readily illuminated root structure, root growth, and relative plant and soil water content. Fungal hyphae associated with the roots were also visible and appeared as dark masses since their diameter was likely several orders of magnitude less than ~100 μm resolution of the detector. The 2D pulse-chase irrigation experiments with H2O and D2O successfully allowed observation of uptake and mass flow of water within the root system. Water flux within individual roots responded differentially to foliar illumination based on internal water potential gradients, illustrating the ability to track root functionality based on root size, order and distribution within the soil. (L) neutron image of switchgrass growing in sandy soil with 100 μm diameter roots (R) 3D reconstruction of maize seedling following neutron tomography

Ethanol synthesis and aerobic respiration in the laboratory by leader segments of Douglas-fir seedlings from winter and spring.

PubMed

Joseph, Gladwin; Kelsey, Rick G

2004-05-01

Stem segments from terminal leaders of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, seedlings were sampled in mid-December when cambial cells were dormant. The residual, debudded leaders were resampled again in early May when the cambium was metabolically active. May stems had higher constitutive ethanol concentrations than December stems. This was not the result of cambial hypoxia generated by rapid spring respiration rates, because when aerobic respiration was stimulated by incubating the stems in air at 30 degrees C ethanol production was induced in December, but not in May. Rapid respiration rates at 30 degrees C may have depleted O(2) supplies and induced ethanol production in December stems because dormant, thick-walled cambial cells may be less permeable to CO(2) and O(2), compared with metabolically active, thin-walled cambial cells in May. December stem segments incubated in a N(2) atmosphere at 30 degrees C synthesized 1.8 times more ethanol than segments from May, most likely because spring growth had reduced the soluble sugars available for fermentation. CO(2) efflux from May stems (after 5.5 h of incubation at 30 degrees C) was equal to December stems per unit volume, but greater than December stems per unit surface area. N(2)-induced ethanol concentrations were positively related with CO(2) efflux per unit volume, indicating that rapidly respiring leaders can maintain rapid fermentation rates, provided soluble sugars are readily available. N(2)-induced ethanol and CO(2) efflux per unit volume declined with increasing leader diameter in both seasons, whereas there were no relationships between CO(2) efflux per unit surface area and diameter. Cambium physiology and phenology influence the induction of fermentation and concentrations of ethanol produced in terminal leaders of Douglas-fir, and probably other conifers as well. This needs to be considered when comparing fermentation among species, or comparing individuals from different seasons, or disparate ages within a species.

The Effects of Herbivory by a Mega- and Mesoherbivore on Tree Recruitment in Sand Forest, South Africa

PubMed Central

Lagendijk, D. D. Georgette; Mackey, Robin L.; Page, Bruce R.; Slotow, Rob

2011-01-01

Herbivory by megaherbivores on woody vegetation in general is well documented; however studies focusing on the individual browsing effects of both mega- and mesoherbivore species on recruitment are scarce. We determined these effects for elephant Loxodonta africana and nyala Tragelaphus angasii in the critically endangered Sand Forest, which is restricted to east southern Africa, and is conserved mainly in small reserves with high herbivore densities. Replicated experimental treatments (400 m2) in a single forest patch were used to exclude elephant, or both elephant and nyala. In each treatment, all woody individuals were identified to species and number of stems, diameter and height were recorded. Results of changes after two years are presented. Individual tree and stem densities had increased in absence of nyala and elephant. Seedling recruitment (based on height and diameter) was inhibited by nyala, and by elephant and nyala in combination, thereby preventing recruitment into the sapling stage. Neither nyala or elephant significantly reduced sapling densities. Excluding both elephant and nyala in combination enhanced recruitment of woody species, as seedling densities increased, indicating that forest regeneration is impacted by both mega- and mesoherbivores. The Sand Forest tree community approached an inverse J-shaped curve, with the highest abundance in the smaller size classes. However, the larger characteristic tree species in particular, such as Newtonia hildebrandtii, were missing cohorts in the middle size classes. When setting management goals to conserve habitats of key importance, conservation management plans need to consider the total herbivore assemblage present and the resulting browsing effects on vegetation. Especially in Africa, where the broadest suite of megaherbivores still persists, and which is currently dealing with the ‘elephant problem’, the individual effects of different herbivore species on recruitment and dynamics of forests and woodlands are important issues which need conclusive answers. PMID:21445345

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.

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.

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.

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

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.

Bacillus amyloliquefaciens L-S60 Reforms the Rhizosphere Bacterial Community and Improves Growth Conditions in Cucumber Plug Seedling

PubMed Central

Qin, Yuxuan; Shang, Qingmao; Zhang, Ying; Li, Pinglan; Chai, Yunrong

2017-01-01

Vegetable plug seedling has become the most important way to produce vegetable seedlings in China. This seedling method can significantly improve the quality and yield of vegetables compared to conventional methods. In the process of plug seedling, chemical fertilizers or pesticides are often used to improve the yield of the seedlings albeit with increasing concerns. Meanwhile, little is known about the impact of beneficial bacteria on the rhizosphere microbiota and the growth conditions of vegetables during plug seedling. In this study, we applied a culture-independent next-generation sequencing-based approach and investigated the impact of a plant beneficial bacterium, Bacillus amyloliquefaciens L-S60, on the composition and dynamics of rhizosphere microbiota and the growth conditions of cucumbers during plug seedling. Our results showed that application of L-S60 significantly altered the structure of the bacterial community associated with the cucumber seedling; presence of beneficial rhizosphere species such as Bacillus, Rhodanobacter, Paenibacillus, Pseudomonas, Nonomuraea, and Agrobacterium was higher upon L-S60 treatment than in the control group. We also measured the impact of L-S60 application on the physiological properties of the cucumber seedlings as well as the availability of main mineral elements in the seedling at different time points during the plug seedling. Results from those measurements indicated that L-S60 application promoted growth conditions of cucumber seedlings and that more available mineral elements were detected in the cucumber seedlings from the L-S60 treated group than from the control group. The findings in this study provided evidence for the beneficial effects of plant growth-promoting rhizosphere bacteria on the bacterial community composition and growth conditions of the vegetables during plug seedling. PMID:29312278

Correlations between polyamine ratios and growth patterns in seedling roots

NASA Technical Reports Server (NTRS)

Shen, H. J.; Galston, A. W.

1985-01-01

The levels of putrescine, cadaverine, spermidine and spermine were determined in seedling roots of pea, tomato, millet and corn, as well as in corn coleoptiles and pea internodes. In all roots, putrescine content increased as elongation progressed, and the putrescine/spermine ratio closely paralleled the sigmoid growth curve up until the time of lateral root initiation. Spermidine and spermine were most abundant near the apices and declined progressively with increasing age of the cells. In the zone of differentiation of root hairs in pea roots, putrescine rose progressively with increasing age, while cadaverine declined. In both pea internodes and corn coleoptiles, the putrescine/spermidine ratio rises with increasing age and elongation. Thus, a block in the conversion of the diamine putrescine to the triamine spermidine may be an important step in the change from cell division to cell elongation.

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.

77 FR 6060 - Small Diameter Graphite Electrodes from the People's Republic of China: Extension of Time Limit...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-07

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-929] Small Diameter Graphite... Department) initiated an administrative review of the antidumping duty order on small diameter graphite... preliminary results of this review by 95 days until February 3, 2012. See Small Diameter Graphite Electrodes...

Effect of pH and calcium on short-term NO3- fluxes in roots of barley seedlings

NASA Technical Reports Server (NTRS)

Aslam, M.; Travis, R. L.; Huffaker, R. C.

1995-01-01

The effect of pH and Ca2+ on net NO3- uptake, influx, and efflux by intact roots of barley (Hordeum vulgare L.) seedlings was studied. Seedlings were induced with NO3- or NO2-. Net NO3- uptake and efflux, respectively, were determined by following its depletion from, and accumulation in, the external solution. Since roots of both uninduced and NO2(-)-induced seedlings contain little internal NO3- initial net uptake rates are equivalent to influx (M. Aslam, R.L. Travis, R.C. Huffaker [1994] Plant Physiol 106: 1293-1301). NO3-, uptake (influx) by these roots was little affected at acidic pH. In contrast, in NO3(-)-induced roots, which accumulate NO3-, net uptake rates decreased in response to acidic pH. Under these conditions, NO3- efflux was stimulated and was a function of root NO3- concentration. Conversely, at basic pH, NO3- uptake by NO3- and NO2(-)-induced and uninduced roots decreased, apparently because of the inhibition of influx. Calcium had little effect on NO3- uptake (influx) by NO2(-)-induced roots at either pH 3 or 6. However, in NO3(-)-induced roots, lack of Ca2+ at pH 3 significantly decreased net NO3- uptake and stimulated efflux. The results indicate that at acidic pH the decrease in net NO3- uptake is due to the stimulation of efflux, whereas at basic pH, it is due to the inhibition of influx.

EMF radiations (1800 MHz)-inhibited early seedling growth of maize (Zea mays) involves alterations in starch and sucrose metabolism.

PubMed

Kumar, Arvind; Singh, Harminder Pal; Batish, Daizy R; Kaur, Shalinder; Kohli, Ravinder Kumar

2016-07-01

The present study investigated the impact of 1800-MHz electromagnetic field radiations (EMF-r), widely used in mobile communication, on the growth and activity of starch-, sucrose-, and phosphate-hydrolyzing enzymes in Zea mays seedlings. We exposed Z. mays to modulated continuous wave homogenous EMF-r at specific absorption rate (SAR) of 1.69±0.0 × 10(-1) W kg(-1) for ½, 1, 2, and 4 h. The analysis of seedlings after 7 days revealed that short-term exposure did not induce any significant change, while longer exposure of 4 h caused significant growth and biochemical alterations. There was a reduction in the root and coleoptile length with more pronounced effect on coleoptile growth (23 % reduction on 4-h exposure). The contents of photosynthetic pigments and total carbohydrates declined by 13 and 18 %, respectively, in 4-h exposure treatments compared to unexposed control. The activity of starch-hydrolyzing enzymes-α- and β-amylases-increased by ∼92 and 94 %, respectively, at an exposure duration of 4 h, over that in the control. In response to 4-h exposure treatment, the activity of sucrolytic enzymes-acid invertases and alkaline invertases-was increased by 88 and 266 %, whereas the specific activities of phosphohydrolytic enzymes (acid phosphatases and alkaline phosphatases) showed initial increase up to ≤2 h duration and then declined at >2 h exposure duration. The study concludes that EMF-r-inhibited seedling growth of Z. mays involves interference with starch and sucrose metabolism.

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

Morpho-anatomical and growth alterations induced by arsenic in Cajanus cajan (L.) DC (Fabaceae).

PubMed

Pita-Barbosa, Alice; Gonçalves, Elton Carvalho; Azevedo, Aristéa Alves

2015-08-01

Arsenic (As) is a toxic element to most organisms. Studies investigating anatomic alterations due to As exposure in plants are scarce but of utmost importance to the establishment of environmental biomonitoring techniques. So, this study aimed to investigate the effects of As on the development and initial root growth in Cajanus cajan (Fabaceae), characterize and quantify the possible damages, evaluate genotoxic effects, and identify structural markers to be used in environmental bioindication. Plants were exposed hydroponically to 0.5, 1.0, 1.5, and 2.0 mg As L(-1), as sodium arsenate. Growth parameters were measured, and in the end of the exposure, root samples were analyzed for qualitative and quantitative anatomical alterations. Arsenic genotoxicity was evaluated through analysis of the mitotic index in the root apex. Compared to the control, As-treated seedlings showed an altered architecture, with significantly decreased root length (due to the lower mitotic index in the apical meristem and reduced elongation of parenchyma cells) with darkened color, and abnormal development of the root cap. A significant increase in vascular cylinder/root diameter ratio was also detected, due to the reduction of the cellular spaces in the cortex. The secondary xylem vessel elements were reduced in diameter and had sinuous walls. The severest damage was visible in the ramification zone, where uncommon division planes of phellogen and cambium cells and disintegration of the parenchyma cells adjacent to lateral roots were observed. The high sensibility of C. cajan to As was confirmed, since it caused severe damages in root growth and anatomy. The main structural markers for As toxicity were the altered root architecture, with the reduction of the elongation zone and increase of ramification zone length, and the root primordia retained within the cortex. Our results show a new approach about As toxicity and indicate that C. cajan is a promising species to be used for bioindication of environmental contamination by As.

Marketing and Seedling Distribution of Longleaf Pine Seedlings

Treesearch

Mark J. Hainds

2002-01-01

The Longleaf Alliance, a partnership of people and organizations interested in longleaf pine, started tracking longleaf pine (Pinus palustris Mill.) seedling production in 1996. Total Longleaf seedling production has increased annually from 1996 to 2000. Bareroot seedling production decreased from 1996 to 1997, and decreased again from 1997 to 1998....

Synthesis of Pisolithus Ectomycorrhizae on Pecan Seedlings in Fumigated Soil

Treesearch

Donald H. Marx

1979-01-01

Curtis variety of pecan (Carya illinoensis) seedlings were grown for 8 months in fumigated soil infested at sowing with mycelial inoculum of Pisolithus tinctorius. Pisolithus ectomycorrhizae were formed on all inoculated seedlings and significantly improved their growth over control seedlings. Inoculated and control seedlings also formed ectomycorrhizae with naturally...

Survival and initial growth attributes of improved and unimproved cherrybark oak in South Arkansas

Treesearch

Joshua P. Adams; David Graves; Matthew H. Pelkki; Chris Stuhlinger; Jon Barry

2015-01-01

Thousands of acres are planted every year with genetically improved seedlings; but while pine continues to be extensively explored, the same is not true for hardwoods due to costs and rotation length. An improved cherrybark oak (Quercus pagodaRaf.) seed orchard exists in North Little Rock, AR, providing an opportunity to evaluate hardwood improvement. However, the cost...

Effects of understory prescribed burning on shortleaf pine (Pinus echinata Mill.)/mixed-hardwood forests

Treesearch

Katherine J. Elliott; James M. Vose

2005-01-01

We examined the effects of a single dormant season fire on overstory and understory species diversity and composition and tree seedling regeneration patterns the first and second years following a prescribed burn in the Conasauga River Watershed of southeastern Tennessee and northern Georgia. We asked: Can a single dormant season fire initiate a trajectory of overstory...

Wildfire rehabilitation success with and without chaining on the Henry Mountains, Utah

Treesearch

Cristina Juran; Bruce A. Roundy; James N. Davis

2008-01-01

We sampled unchained and chained areas in 2004 and 2005 on the Henry Mountains that had been aerially seeded after the Bulldog Fire of 2003. Establishment of seeded grasses was high on unchained and chained areas although chaining increased seeded grass establishment on some sites. Western yarrow established well on unchained areas. Initially, high seedling emergence...

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...

Role of fire in regeneration from seed: Chapter 14

USGS Publications Warehouse

Keeley, Jon E.; Fotheringham, C.J.; Fenner, M.

2000-01-01

The effects of fire on seed germination and plant regeneration are discussed. Among the topics considered are the triggering of opening of serotinous fruits or cones by fire, the breaking of dormancy in seeds in the soil seed bank, the effects of smoke on germination, and the role of fire in initiating seedling recruitment by opening gaps in closed vegetation.

Seedling response to initial oak woodland restoration treatments on the Ozark National Forest

Treesearch

Jamie L. Schuler; Don C. Bragg; Eric Heitzman; Jason Milks

2013-01-01

Over the last century, the range of oak woodland ecosystems has diminished as woodlands have become more closed-canopy forests. A century of fire suppression efforts has all but eliminated the frequent ground fires necessary to maintain the open canopy characteristics of oak woodland ecosystems. Restoration efforts are underway to return some of the closed-canopy...

Accelerated Growth and Initial Flowering of S2 Pinus Banksiana Selected for Precocious Flowering

Treesearch

Hyun Kang; Robert A. Cecich

1999-01-01

An accelerated growth protocol was applied in a greenhouse to hasten flowering in 13 S2 lines of jack pine (Pinus banksiana Lamb.) selected for precocious flowering. Seeds were sown on October 1. After the artificial "summer, fall, winter, and spring," seedlings were placed outdoors between June 20 and November 1. Ovulate strobili were...

Effects of prescribed burning on vegetation and fuel loading in three east Texas state parks

Treesearch

Sandra Rideout; Brian P. Oswald

2002-01-01

This study was conducted to evaluate the initial effectiveness of prescribed burning in the ecological restoration of forests within selected parks in east Texas. Twenty-four permanent plots were installed to monitor fuel loads, overstory, sapling, seedling, shrub and herbaceous layers within burn and control units of Mission Tejas, Tyler and Village Creek state parks...

The efficiency of introduced pisolithus tinctorius inoculum on backcrossed chestnut germination and survival

Treesearch

Jenise M. Bauman; Carolyn H. Keiffer; Shiv Hiremath

2012-01-01

American chestnut was eliminated as a canopy tree from the Appalachian region of North America with the introduction of chestnut blight in the early 1900s. Breeding programs initiated in the 1980s have produced seedling lines that display the pure American morphology with potential resistance to chestnut blight. More work is required to assess their field performance...

Transient heat stress compromises the resistance of wheat (Poales: Poaceae) seedlings to Hessian fly (Diptera: Cecidomyiidae) infestation.

PubMed

Currie, Yaleaka; Moch, John; Underwood, Joshua; Kharabsheh, Hamzah; Quesenberry, Amy; Miyagi, Risa; Thomas, Carolyn; Boney, Melanie; Woods, Samantha; Chen, Ming-Shun; Zhu, Lieceng

2014-02-01

Heat stress exerts a profound impact on the resistance of plants to parasites. In this research, we investigated the impact of an acute transient heat stress on the resistance of the wheat line 'Molly,' which contains the R gene H13, to an avirulent Hessian fly (Mayetiola destructor (Say)) population. We found that a significant portion of Molly seedlings stressed at 40 degrees C for 6 h during or after the initial Hessian fly larval attack became susceptible to otherwise avirulent insects, whereas unstressed control plants remained 100% resistant. Specifically, 77.8, 73.3, 83.3, and 46.7% of plants heat stressed at 0, 6,12, and 24 h, respectively, after the initial larval attack became susceptible. Biochemical analysis revealed that heat stress caused a transient decrease in 12-oxo-phytodienoic acid, but an increase in salicylic acid accumulation in Molly plants. The change in phytohormones after heat stress and Hessian fly infestation was not observed in 'Newton,' a near-isogenic but Hessian fly susceptible wheat line. Instead, heat stress caused a relatively prolonged reduction in palmitoleic acid. The role of phytohormones in heat-induced loss of wheat resistance was discussed.

Combined effects of cotyledon excision and nursery fertilization on root growth, nutrient status and outplanting performance of Quercus variabilis container seedlings

PubMed Central

Shi, Wenhui; Bloomberg, Mark; Li, Guolei; Su, Shuchai; Jia, Liming

2017-01-01

Artificial excision of the distal part of acorns in order to promote germination is well researched in oak seedling cultivation studies. However, studies of combined effects of cotyledon excision and nursery fertilization on container seedlings are lacking, especially for seedling root growth and outplanting performance. This study aimed to explore the main effects of cotyledon excision on Quercus variabilis seedling emergence characteristics and demonstrated the combined effects of cotyledon excision and nursery fertilization on seedling quality to improve Quercus variabilis seedling outplanting performance. Four cotyledon excision treatments and two classes of nursery fertilization were implemented. Seedling emergence was noted every week after sowing. Seedling dry mass, morphology, and nutrient status were assessed at the end of the nursery season. After the first outplanting season, the aforementioned measurements along with seedling survival were determined once again. The results showed that cotyledon excision generally induced greater and more rapid seedling emergence, but did not affect shoot emergence synchronicity. The highest total emergence and emergence rate occurred with Intermediate excision (1/2 of the distal end of acorn was excised). Effects of nutrient loss due to cotyledon excision on seedling quality and outplanting performance were somewhat compensated by nursery fertilization. Nursery fertilization promoted dry mass increment (the net increment from T0 to T2 for dry mass) for excised seedlings after outplanting, resulting in better performance for Slight (1/3 of the distal end of acorn was excised) and Intermediate excision treatments in the field. Thus we conclude Intermediate excision combined with reasonable nursery fertilization can be recommended for production of nursery grown seedlings for afforestation. PMID:28545103

Combined effects of cotyledon excision and nursery fertilization on root growth, nutrient status and outplanting performance of Quercus variabilis container seedlings.

PubMed

Shi, Wenhui; Bloomberg, Mark; Li, Guolei; Su, Shuchai; Jia, Liming

2017-01-01

Artificial excision of the distal part of acorns in order to promote germination is well researched in oak seedling cultivation studies. However, studies of combined effects of cotyledon excision and nursery fertilization on container seedlings are lacking, especially for seedling root growth and outplanting performance. This study aimed to explore the main effects of cotyledon excision on Quercus variabilis seedling emergence characteristics and demonstrated the combined effects of cotyledon excision and nursery fertilization on seedling quality to improve Quercus variabilis seedling outplanting performance. Four cotyledon excision treatments and two classes of nursery fertilization were implemented. Seedling emergence was noted every week after sowing. Seedling dry mass, morphology, and nutrient status were assessed at the end of the nursery season. After the first outplanting season, the aforementioned measurements along with seedling survival were determined once again. The results showed that cotyledon excision generally induced greater and more rapid seedling emergence, but did not affect shoot emergence synchronicity. The highest total emergence and emergence rate occurred with Intermediate excision (1/2 of the distal end of acorn was excised). Effects of nutrient loss due to cotyledon excision on seedling quality and outplanting performance were somewhat compensated by nursery fertilization. Nursery fertilization promoted dry mass increment (the net increment from T0 to T2 for dry mass) for excised seedlings after outplanting, resulting in better performance for Slight (1/3 of the distal end of acorn was excised) and Intermediate excision treatments in the field. Thus we conclude Intermediate excision combined with reasonable nursery fertilization can be recommended for production of nursery grown seedlings for afforestation.

Root-type-specific plasticity in response to localized high nitrate supply in maize (Zea mays).

PubMed

Yu, Peng; Hochholdinger, Frank; Li, Chunjian

2015-10-01

Shoot-borne roots contribute to most of the nutrient uptake throughout the life cycle of maize (Zea mays). Compared with numerous studies with embryonic roots, detailed information on the phenotypic plasticity of shoot-borne roots in response to a heterogeneous nitrogen supply is scarce. The present study therefore provides a comprehensive profile of fine-scale plastic responses of distinct root types to localized high nitrate supply. Seedlings of the maize inbred line B73 were grown in split-root systems. The anatomy and morphological plasticity of the primary root and the roots initiated from the 2nd, 5th and 7th shoot nodes, and their lateral roots, were studied in response to local high nitrate supply to one side of the root system. In contrast to the insensitivity of axial roots, local high nitrate supply increased the length of 1st-order lateral roots on the primary root and the three whorls of shoot-borne roots at different growth stages, and increased the density of 1st-order lateral roots on the 7th shoot-borne root after silking. The length and density of 2nd-order lateral roots on the three whorls of shoot-borne roots displayed a more flexible response to local high nitrate than 1st-order lateral roots. Root diameter and number, and total area and diameter of metaxylem vessels increased from the primary root to early and then later developed shoot-borne roots, which showed a positive relationship with shoot growth and N accumulation. Maize axial roots and lateral roots responded differently to local high nitrate, and this was related to their function. The extent of morphological plasticity of lateral roots in response to local high nitrate depended on the initiation time of the shoot-borne roots on which the lateral roots developed. Morphological plasticity was higher on 2nd-order than on 1st-order lateral roots. The results suggest that higher order lateral root branching might be a potential target for genetic improvement in future maize breeding. © 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.

Morphological and physiological evaluations of seedling quality

Treesearch

Diane L. Haase

2007-01-01

Seedling quality and subsequent field performance can be influenced by various stress factors. Measuring seedling quality can help to identify possible crop problems in order to make informed decisions for culturing, lifting, storing, and planting. In addition, seedling quality data can help seedling growers and users to better understand annual patterns among species...

Effects of vesicular-arbuscular mycorrhizal (VAM) fungi on the seedling growth of three Pistacia species.

PubMed

Caglar, S; Akgun, A

2006-07-01

The experiment was undertaken to test the efficiency of inoculation of vesicular-arbuscular mycorrhizal (VAM) fungi on the seedling growth of three Pistacia species used as rootstocks. The stratified Pistacia seeds were inoculated with VAM fungi. The highest rate of inoculated roots was 96.7% in P. khinjuck seedlings with G. clarum and G. etunicatum, 83.3% in P. vera seedlings with G. caledonium and 73.3% in P. terebinthus seedlings with G. caledonium. Mycorrhizal inoculations improved seedling height only in P. terebinthus. Certain mycorrhizal inoculations increased the leaf N, but not P and K contents. Seedlings inoculated with G. caledonium had higher reducing sugar contents. It was concluded that pre-inoculated Pistacia seedlings could have a better growth in the harsh field conditions.

The potential for mycobiont sharing between shrubs and seedlings to facilitate tree establishment after wildfire at Alaska arctic treeline.

PubMed

Hewitt, Rebecca E; Chapin, F Stuart; Hollingsworth, Teresa N; Taylor, D Lee

2017-07-01

Root-associated fungi, particularly ectomycorrhizal fungi (EMF), are critical symbionts of all boreal tree species. Although climatically driven increases in wildfire frequency and extent have been hypothesized to increase vegetation transitions from tundra to boreal forest, fire reduces mycorrhizal inoculum. Therefore, changes in mycobiont inoculum may potentially limit tree-seedling establishment beyond current treeline. We investigated whether ectomycorrhizal shrubs that resprout after fire support similar fungal taxa to those that associate with tree seedlings that establish naturally after fire. We then assessed whether mycobiont identity correlates with the biomass or nutrient status of these tree seedlings. The majority of fungal taxa observed on shrub and seedling root systems were EMF, with some dark septate endophytes and ericoid mycorrhizal taxa. Seedlings and adjacent shrubs associated with similar arrays of fungal taxa, and there were strong correlations between the structure of seedling and shrub fungal communities. These results show that resprouting postfire shrubs support fungal taxa compatible with tree seedlings that establish after wildfire. Shrub taxon, distance to the nearest shrub and fire severity influenced the similarity between seedling and shrub fungal communities. Fungal composition was correlated with both foliar C:N ratio and seedling biomass and was one of the strongest explanatory variables predicting seedling biomass. While correlative, these results suggest that mycobionts are important to nutrient acquisition and biomass accrual of naturally establishing tree seedlings at treeline and that mycobiont taxa shared by resprouting postfire vegetation may be a significant source of inoculum for tree-seedling establishment beyond current treeline. © 2017 John Wiley & Sons Ltd.

Simulation on Effect of Preform Diameter in Injection Stretch Blow Molding

NASA Astrophysics Data System (ADS)

Tan, Z. Q.; Rosli, Nurrina; Oktaviandri, Muchamad

2018-03-01

Polyethylene terephthalate (PET) is the most common material of resin for manufacturing plastic bottle by injection stretch blow molding due to its excellent properties. As various issues of health and environmental hazards due to the PET use have risen, PET bottle manufacture may be improved by minimizing the wall thickness to reduce the PET use. One of the critical qualifications of the manufacturing process which lead to the wall thickness distribution is the initial preform diameter. In this project, we used the ANSYS Polyflow with aim to evaluate the wall thickness distribution of PET bottle for different diameter of initial preform. As a result, only 4 mm preform diameter presented wall thickness below than 1 mm. On the other hand, at least 6 mm preform diameter can permit the wall thickness 1.3 mm i.e. at the shoulder area.

Controlled release fertilizer improves quality of container longleaf pine seedlings

Treesearch

R. Kasten Dumroese; Jeff Parkhurst; James P. Barnett

2005-01-01

In an operational trial, increasing the amount of nitrogen (N) applied to container longleaf pine seedlings by incorporating controlled release fertilizer (CRF) into the media improved seedling growth and quality. Compared with control seedlings that received 40 mg N, seedlings receiving 66 mg N through CRF supplemented with liquid fertilizer had needles that were 4 in...

Winter injury among white fir seedlings...unusual pattern in seed source study

Treesearch

M. Thompson Conkle; W. J. Libby; J. L. Hamrick

1967-01-01

White fir seeds collected from 43 sources were sown at the Institute of Forest Genetics, Placerville, Calif. in 1963. Observations made 3 years later showed that seedlings from northern sources sustained more winter injury than did southern origin seedlings. Seedlings from low elevations were less severely damaged than seedlings from higher elevations in the same...

Interaction of Soil Moisture and Seedling Shelters on Water Relations of Baldcypress Seedlings

Treesearch

Ty Swirin; Hans Williams; Bob Keeland

1999-01-01

Stomata1 conductance, transpiration, and leaf water potential were measured during the 1996 growing season on baldcypress (Taxodium disfichum (L.) Rich.) seedlings. Seedlings were hand-planted from 1-O bareroot stock in mesic and permanently Rooded soil conditions. One-half of all seedlings were fitted with 122-cm tall polyethylene tree...

Spring Burn Aids Longleaf Pine Seedling Height Growth

Treesearch

William R. Maple

1977-01-01

Prescribed burning in midspring may stimulate height growth of longleaf pine seedlings. Seedlings were planted on sandy and clayey sites that were prescribed burned 2 years later. Treatments were cool, moderate, and hot burns and an unburned control. The hot, May burn significantly increased height growth of seedlings on the sandy site. The number of seedlings with 50...

Protecting red oak seedlings with tree shelters in northwestern Pennsylvania

Treesearch

Russell S. Walters; Russell S. Walters

1993-01-01

Examines the growth and survival of planted and natural red oak seedlings and seedlings from planted acorns within translucent tan tree shelters, fences, and unprotected controls under a shelterwood seed-cut stand. Seedlings planted within tree shelters and fences were inside tree shelters. Natural seedlings grew very little and their height inside and outside of tree...

A comparison of tree shelters installed on green ash and cherrybark oak seedlings in Arkansas

Treesearch

H. Christoph Stuhlinger

2013-01-01

Tree shelters can aid hardwood seedling establishment by improving early seedling survival and growth. This study was established in Arkansas to compare three types of tree shelters installed on green ash (Fraxinus pennsylvanica Marsh.) and cherrybark oak (Quercus pagoda Raf.) seedlings. Seedlings planted in 4 feet tall Blue-X®,...

Ethylene-Inhibited Jasmonic Acid Biosynthesis Promotes Mesocotyl/Coleoptile Elongation of Etiolated Rice Seedlings[OPEN

PubMed Central

Xiong, Qing; Ma, Biao; Lu, Xiang; Huang, Yi-Hua; He, Si-Jie; Yang, Chao; Yin, Cui-Cui; Zhou, Yang; Wang, Wen-Sheng; Li, Zhi-Kang; Chen, Shou-Yi

2017-01-01

Elongation of the mesocotyl and coleoptile facilitates the emergence of rice (Oryza sativa) seedlings from soil and is affected by various genetic and environment factors. The regulatory mechanism underlying this process remains largely unclear. Here, we examined the regulation of mesocotyl and coleoptile growth by characterizing a gaoyao1 (gy1) mutant that exhibits a longer mesocotyl and longer coleoptile than its original variety of rice. GY1 was identified through map-based cloning and encodes a PLA1-type phospholipase that localizes in chloroplasts. GY1 functions at the initial step of jasmonic acid (JA) biosynthesis to repress mesocotyl and coleoptile elongation in etiolated rice seedlings. Ethylene inhibits the expression of GY1 and other genes in the JA biosynthesis pathway to reduce JA levels and enhance mesocotyl and coleoptile growth by promoting cell elongation. Genetically, GY1 acts downstream of the OsEIN2-mediated ethylene signaling pathway to regulate mesocotyl/coleoptile growth. Through analysis of the resequencing data from 3000 rice accessions, we identified a single natural variation of the GY1 gene, GY1376T, which contributes to mesocotyl elongation in rice varieties. Our study reveals novel insights into the regulatory mechanism of mesocotyl/coleoptile elongation and should have practical applications in rice breeding programs. PMID:28465411

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.

Trichoderma harzianum containing 1-aminocyclopropane-1-carboxylate deaminase and chitinase improved growth and diminished adverse effect caused by Fusarium oxysporum in soybean.

PubMed

Zhang, Fuli; Chen, Can; Zhang, Fan; Gao, Lidong; Liu, Jidong; Chen, Long; Fan, Xiaoning; Liu, Chang; Zhang, Ke; He, Yuting; Chen, Chen; Ji, Xiue

2017-03-01

An isolate, named Trichoderma harzianum T-soybean, showed growth-promoting for soybean seedlings and induced resistance to Fusarium oxysporum under greenhouse. Compared to control soybean seedlings, fresh weight, dry weight, lateral root number, chlorophyll content, root activity and soluble protein of plants pretreated with T-soybean increased, but initial pod height reduced. Furthermore, we found that T-soybean inhibited the growth of F. oxysporum by parasitic function. In addition, plate test results showed that culture filtrates of T-soybean also inhibited significantly F. oxysporum growth. Meanwhile, T-soybean treatment obviously reduced disease severity and induced quickly the H 2 O 2 and O 2 - burst as well as pathogenesis related protein gene (PR3) expression after F. oxysporum inoculation, and subsequently diminished the cell damage in soybean caused by the pathogen challenge. Reactive oxygen species (ROS) scavenging enzymes activity analysis showed that the activities of peroxidase (POD), polyphenol oxidase (PPO) and superoxide dismutase (SOD) increased significantly in T-soybean pretreated plants. These results suggested that T-soybean treatment induced resistance in soybean seedlings to F. oxysporum by companying the production of ROS and the increasing of ROS scavenging enzymes activity as well as PR3 expression. Copyright © 2016 Elsevier GmbH. All rights reserved.

Establishing northern red oak on a degraded upland site in northeastern Pennsylvania: Influence of seedling pedigree and quality

Treesearch

Cornelia C. Pinchot; Thomas J. Hall; Scott E. Schlarbaum; Arnold M. Saxton; James Bailey

2017-01-01

Enrichment plantings using large oak seedlings of regional sources may promote superior survival and growth compared to direct seeding or standard nursery seedling material. This study evaluated the survival and growth of planted 1-0 northern red oak (Quercus rubra L.) seedlings among 11 families and 3 seedling size classes (small, average, and...

Combined effects of pre-hardening and fall fertilization on nitrogen translocation and storage in Quercus variabilis seedlings

Treesearch

Guolei Li; Yan Zhu; Yong Liu; Jiaxi Wang; Jiajia Liu; R. Kasten Dumroese

2014-01-01

Maintaining proper seedling nitrogen status is important for outplanting success. Fall fertilization of evergreen conifer seedlings is a well-known technique for averting nitrogen (N) dilution caused by continued seedling growth during hardening. For deciduous seedlings, this technique is much less understood, and regardless of foliage type, the interaction of N status...

Arbuscular Mycorrhizal Symbiosis Modulates Antioxidant Response and Ion Distribution in Salt-Stressed Elaeagnus angustifolia Seedlings.

PubMed

Chang, Wei; Sui, Xin; Fan, Xiao-Xu; Jia, Ting-Ting; Song, Fu-Qiang

2018-01-01

Elaeagnus angustifolia L. is a drought-resistant species. Arbuscular mycorrhizal symbiosis is considered to be a bio-ameliorator of saline soils that can improve salinity tolerance in plants. The present study investigated the effects of inoculation with the arbuscular mycorrhizal fungus Rhizophagus irregularis on the biomass, antioxidant enzyme activities, and root, stem, and leaf ion accumulation of E. angustifolia seedlings grown during salt stress conditions. Salt-stressed mycorrhizal seedlings produced greater root, stem, and leaf biomass than the uninoculated stressed seedlings. In addition, the seedlings colonized by R. irregularis showed notably higher activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) in the leaves of the mycorrhizal seedlings in response to salinity compared to those of the non-mycorrhizal seedlings. Mycorrhizal seedlings not only significantly increased their ability to acquire K + , Ca 2+ , and Mg 2+ , but also maintained higher K + :Na + ratios in the leaves and lower Ca 2+ :Mg 2+ ratios than non-mycorrhizal seedlings during salt stress. These results suggest that the salt tolerance of E. angustifolia seedlings could be enhanced by R. irregularis. The arbuscular mycorrhizal symbiosis could be a promising method to restore and utilize salt-alkaline land in northern China.

Arbuscular Mycorrhizal Symbiosis Modulates Antioxidant Response and Ion Distribution in Salt-Stressed Elaeagnus angustifolia Seedlings

PubMed Central

Chang, Wei; Sui, Xin; Fan, Xiao-Xu; Jia, Ting-Ting; Song, Fu-Qiang

2018-01-01

Elaeagnus angustifolia L. is a drought-resistant species. Arbuscular mycorrhizal symbiosis is considered to be a bio-ameliorator of saline soils that can improve salinity tolerance in plants. The present study investigated the effects of inoculation with the arbuscular mycorrhizal fungus Rhizophagus irregularis on the biomass, antioxidant enzyme activities, and root, stem, and leaf ion accumulation of E. angustifolia seedlings grown during salt stress conditions. Salt-stressed mycorrhizal seedlings produced greater root, stem, and leaf biomass than the uninoculated stressed seedlings. In addition, the seedlings colonized by R. irregularis showed notably higher activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) in the leaves of the mycorrhizal seedlings in response to salinity compared to those of the non-mycorrhizal seedlings. Mycorrhizal seedlings not only significantly increased their ability to acquire K+, Ca2+, and Mg2+, but also maintained higher K+:Na+ ratios in the leaves and lower Ca2+:Mg2+ ratios than non-mycorrhizal seedlings during salt stress. These results suggest that the salt tolerance of E. angustifolia seedlings could be enhanced by R. irregularis. The arbuscular mycorrhizal symbiosis could be a promising method to restore and utilize salt-alkaline land in northern China. PMID:29675008

Root growth, secondary root formation and root gravitropism in carotenoid-deficient seedlings of Zea mays L

NASA Technical Reports Server (NTRS)

Ng, Y. K.; Moore, R.

1985-01-01

The effect of ABA on root growth, secondary-root formation and root gravitropism in seedlings of Zea mays was investigated by using Fluridone-treated seedlings and a viviparous mutant, both of which lack carotenoids and ABA. Primary roots of seedlings grown in the presence of Fluridone grew significantly slower than those of control (i.e. untreated) roots. Elongation of Fluridone-treated roots was inhibited significantly by the exogenous application of 1 mM ABA. Exogenous application of 1 micromole and 1 nmole ABA had either no effect or only a slight stimulatory effect on root elongation, depending on the method of application. The absence of ABA in Fluridone-treated plants was not an important factor in secondary-root formation in seedlings less than 9-10 d old. However, ABA may suppress secondary-root formation in older seedlings, since 11-d-old control seedlings had significantly fewer secondary roots than Fluridone-treated seedlings. Roots of Fluridone-treated and control seedlings were graviresponsive. Similar data were obtained for vp-9 mutants of Z. mays, which are phenotypically identical to Fluridone-treated seedlings. These results indicate that ABA is necessary for neither secondary-root formation nor for positive gravitropism by primary roots.

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.

Tree proximity, soil pathways and common mycorrhizal networks: their influence on the utilization of redistributed water by understory seedlings.

PubMed

Schoonmaker, Amanda L; Teste, François P; Simard, Suzanne W; Guy, Robert D

2007-12-01

Hydraulic redistribution (HR) is a process by which water moves through plant roots from moist to dry soils. An experiment was conducted to quantify the influence of common mycorrhizal networks (CMNs) and proximity to mature HR-source trees on the water relations of surrounding seedlings. Douglas-fir (Pseudotsuga menziesii var glauca (Mirb.) Franco) seedlings were planted at four distances (0.5, 1, 2.5, and 5 m) from six mature Douglas-fir trees, either directly into soil (soil plus CMN pathway) or inside 0.5 microm mesh bags (soil-only pathway). Deuterated water was used to irrigate soil beside mature trees in order to identify different HR water pathways to surrounding seedlings. This was followed by measurements of seedling deuterium enrichment, seedling water potential, soil water potential, gravimetric soil water content, and tree root density surrounding the seedlings. There was no significantly detectable difference in the quantity of HR water transferred to seedlings having access to soil and CMN pathways or soil-only pathways of water movement. Water from the irrigation plot contributed up to 1.4% of the water of Douglas-fir seedlings. Based on the assumption that the only pathway through which seedlings could access irrigation water was through the mature trees, we estimate that as much as 21.6% of the seedling water was supplied by the nearby tree. Seedling water potential was not significantly affected either by proximity to mature trees or pathway, suggesting HR may have compensated for increasing tree competitive effects with proximity. It is also possible that the lack of difference was due to a relatively moist summer. Our results suggest that residual mature trees are potentially important for hydraulic redistribution to regenerating seedlings in harvested dry interior Douglas-fir forests.

Tree fern trunks facilitate seedling regeneration in a productive lowland temperate rain forest.

PubMed

Gaxiola, Aurora; Burrows, Larry E; Coomes, David A

2008-03-01

Seedling regeneration on forest floors is often impaired by competition with established plants. In some lowland temperate rain forests, tree fern trunks provide safe sites on which tree species establish, and grow large enough to take root in the ground and persist. Here we explore the competitive and facilitative effects of two tree fern species, Cyathea smithii and Dicksonia squarrosa, on the epiphytic regeneration of tree species in nutrient-rich alluvial forests in New Zealand. The difficulties that seedlings have in establishing on vertical tree fern trunks were indicated by the following observations. First, seedling abundance was greatest on the oldest sections of tree fern trunks, near the base, suggesting that trunks gradually recruited more and more seedlings over time, but many sections of trunk were devoid of seedlings, indicating the difficulty of establishment on a vertical surface. Second, most seedlings were from small-seeded species, presumably because smaller seeds can easily lodge on tree fern trunks. Deer browsing damage was observed on 73% of epiphytic seedlings growing within 2 m of the ground, whereas few seedlings above that height were browsed. This suggests that tree ferns provide refugia from introduced deer, and may slow the decline in population size of deer-preferred species. We reasoned that tree ferns would compete with epiphytic seedlings for light, because below the tree fern canopy photosynthetically active radiation (PAR) was about 1% of above-canopy PAR. Frond removal almost tripled %PAR on the forest floor, leading to a significant increase in the height growth rate (HGR) of seedlings planted on the forest floor, but having no effects on the HGRs of epiphytic seedlings. Our study shows evidence of direct facilitative interactions by tree ferns during seedling establishment in plant communities associated with nutrient-rich soils.

Combined Inoculation with Multiple Arbuscular Mycorrhizal Fungi Improves Growth, Nutrient Uptake and Photosynthesis in Cucumber Seedlings.

PubMed

Chen, Shuangchen; Zhao, Hongjiao; Zou, Chenchen; Li, Yongsheng; Chen, Yifei; Wang, Zhonghong; Jiang, Yan; Liu, Airong; Zhao, Puyan; Wang, Mengmeng; Ahammed, Golam J

2017-01-01

Mycorrhizal inoculation stimulates growth, photosynthesis and nutrient uptake in a wide range of host plants. However, the ultimate effects of arbuscular mycorrhyzal (AM) symbiosis vary with the plants and fungal species involved in the association. Therefore, identification of the appropriate combinations of AM fungi (AMF) that interact synergistically to improve their benefits is of high significance. Here, three AM fungal compositions namely VT ( Claroideoglomus sp., Funneliformis sp., Diversispora sp., Glomus sp., and Rhizophagus sp.) and BF ( Glomus intraradices , G. microageregatum BEG and G. Claroideum BEG 210), and Funneliformis mosseae (Fm) were investigated with respect to the growth, gas exchange parameters, enzymes activities in Calvin cycles and related gene expression in cucumber seedlings. The results showed that VT, BF and Fm could successfully colonize cucumber root to a different degree with the colonization rates 82.38, 74.65, and 70.32% at 46 days post inoculation, respectively. The plant height, stem diameter, dry weight, root to shoot ratio of cucumber seedlings inoculated with AMF increased significantly compared with the non-inoculated control. Moreover, AMF colonization greatly increased the root activity, chlorophyll content, net photosynthetic rate, light saturated rate of the CO 2 assimilation ( A sat), maximum carboxylation rate ( V cmax ) and maximum ribulose-1,5-bis-phosphate (RuBP) regeneration rate ( J max), which were increased by 52.81, 30.75, 58.76, 47.00, 69.15, and 65.53% when inoculated with VT, respectively. The activities of some key enzymes such RuBP carboxylase/oxygenase (RuBisCO), D-fructose-1,6-bisphosphatase (FBPase), D-fructose-6-phosphatase (F6P) and ribulose-5-phosphate kinase (Ru5PK), and related gene expression involved in the Calvin cycle including RCA , FBPase , FBPA , SBPase , rbcS and rbcL were upregulated by AMF colonization. AMF inoculation also improved macro- and micro nutrient contents such as N, P, K, S, Ca, Cu, Fe, Mn, Mg, and Zn in roots. Further analysis revealed that inoculation with VT had relatively better effect on growth of cucumber seedling followed by BF and Fm, indicating that AMF composition consisting of distant AMF species may have a better effect than a single or closely related AMF spp. This study advances the understanding of plant responses to different AM fungi toward development of strategies on AMF-promoted vegetable production.

Inoculation of fumigated nursery beds and containers with arbuscular mycorrhizal products for eastern redcedar production

Treesearch

Michelle M. Cram; Stephen W. Fraedrich

2015-01-01

Commercially available arbuscular mycorrhizal (AM) products were applied at an operational rate to eastern redcedar (Juniperus virginiana L.) nursery beds and containers to evaluate seedling growth and colonization responses. A field study at the Augusta Forestry Center in Crimora, VA, and a companion container study were initiated in the fall of 2012. MycoApply® Endo...

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...

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...

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.

Effects of seedling size, El Niño drought, seedling density, and distance to nearest conspecific adult on 6-year survival of Ocotea whitei seedlings in Panamá.

PubMed

Gilbert, Gregory S; Harms, Kyle E; Hamill, David N; Hubbell, Stephen P

2001-05-01

We present an analysis of the long-term survival of two cohorts of seedlings of the tropical canopy tree Ocotea whitei (Lauraceae) on a 1-ha plot of mature, lowland moist forest on Barro Colorado Island, Panamá. In 1980, we counted an even-aged cohort of seedlings that germinated in 1979, then measured and tagged survivors in 1981. We also measured and tagged a second, smaller cohort of seedlings that germinated in 1981. We followed the subsequent survival of all seedlings through 1985. Seedling mortality was phenotypically, temporally, and spatially non-random. Important correlates of non-random mortality included: (1) seedling size and age, (2) an El Niño drought, and (3) biotic neighborhood. Larger and older seedlings survived better than smaller and younger seedlings, respectively, and the El Niño-related drought of 1982-1983 was associated with elevated mortality rates. Seedling density, which was strongly correlated with the proximity to the nearest conspecific adult, increased mortality. The observed mortality patterns suggest that processes consistent with the Janzen-Connell hypothesis operate during the recruitment phase of O. whitei population dynamics. However, the processes causing the observed density- and distance-dependent mortality may vary with factors such as total seed number, seedling size, and climatic variation, making it difficult to determine whether time-integrated seedling-to-adult spacing mechanisms other than self-thinning operate on a given plant population. After 6 years in the hectare studied, survivors remained densest and most numerous underneath the adult trees. We conclude that only long-term demographic data, collected at a variety of scales on a variety of species, will ultimately answer the question: do Janzen-Connell effects contribute substantially to structuring tropical forests?

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

Schuman, G.E.; Stahl, P.D.; Williams, S.E.

Reestablishment of Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) on mined lands has been difficult in the past even though it is widespread in the western US. Its reestablishment on mined lands has recently become law where wildlife is one of the post-mining land uses and it represented the primary premining shrub species. One hypothesis thought to contribute to its difficult reestablishment is the reduce lack of mycorrhizae inoculum present in the disturbed topsoil and the resulting effect on the seedling`s ability to extract water from the soil under the arid/semiarid climate of this region. A greenhouse study was conductedmore » to evaluate the effect of mycorrhizae on sagebrush seedling water stress tolerance. Seedling ages evaluated ranged from 30 to 150 days. Seedling survival was greater for mycorrhizal seedlings compared to non-mycorrhizal seedlings when soil moisture tension was {minus}2.5 to {minus}3.8 MPa. At all ages, the degree of soil dryness necessary to cause sagebrush seedling mortality was significantly greater for mycorrhizal than non-mycorrhizal seedlings. Seedling age and mycorrhizal infection exhibited a significant statistical interaction; suggesting that as the sagebrush seedling aged, the benefits of arbuscular mycorrhizae (AM) increased the plants water stress tolerance. These findings lead the authors to conclude that topsoil management that prevents/reduces the loss of AM inoculum in the topsoil will significantly enhance the success of sagebrush establishment on mined lands.« less

Historical forest seedling production in the southern United States: 2008 to 2009 planting season

Treesearch

Scott A. Enebak

2011-01-01

Seedling production across the southern US for the 2008 to 2009 planting season was 1.05 billion seedlings, a decrease of 53.6 million (5%) from the 2007 to 2008 planting season. The vast majority (90%) of reduction in conifer seedling production from 2008 was bareroot loblolly (Pinus taeda) and slash (P. elliottii) pine. Hardwoods were about 1% of regional seedling...

Effects of Lifting Method, Seedling Size, and Herbaceous Weed Control on First-Year Growth of Loblolly Pine Seedlings

Treesearch

Jason P. Reynolds; Thomas A. Greene; John R. Britt

2002-01-01

In fall, 1999, an experiment was installed to measure the effects and interactions of lifting method, seedling size, and weed competition on growth of loblolly pine (P. teada) seedlings during the first two growing seasons. Loblolly pine seedlings grown at two bed densities and lifted either by hand or machine were planted in southwestern Georgia...

UV-B inhibition of hypocotyl growth in etiolated Arabidopsis thaliana seedlings is a consequence of cell cycle arrest initiated by photodimer accumulation

PubMed Central

Biever, Jessica J.; Brinkman, Doug; Gardner, Gary

2014-01-01

Ultraviolet (UV) radiation is an important constituent of sunlight that determines plant morphology and growth. It induces photomorphogenic responses but also causes damage to DNA. Arabidopsis mutants of the endonucleases that function in nucleotide excision repair, xpf-3 and uvr1-1, showed hypersensitivity to UV-B (280–320nm) in terms of inhibition of hypocotyl growth. SOG1 is a transcription factor that functions in the DNA damage signalling response after γ-irradiation. xpf mutants that carry the sog1-1 mutation showed hypocotyl growth inhibition after UV-B irradiation similar to the wild type. A DNA replication inhibitor, hydroxyurea (HU), also inhibited hypocotyl growth in etiolated seedlings, but xpf-3 was not hypersensitive to HU. UV-B irradiation induced accumulation of the G2/M-specific cell cycle reporter construct CYCB1;1-GUS in wild-type Arabidopsis seedlings that was consistent with the expected accumulation of photodimers and coincided with the time course of hypocotyl growth inhibition after UV-B treatment. Etiolated mutants of UVR8, a recently described UV-B photoreceptor gene, irradiated with UV-B showed inhibition of hypocotyl growth that was not different from that of the wild type, but they lacked UV-B-specific expression of chalcone synthase (CHS), as expected from previous reports. CHS expression after UV-B irradiation was not different in xpf-3 compared with the wild type, nor was it altered after HU treatment. These results suggest that hypocotyl growth inhibition by UV-B light in etiolated Arabidopsis seedlings, a photomorphogenic response, is dictated by signals originating from UV-B absorption by DNA that lead to cell cycle arrest. This process occurs distinct from UVR8 and its signalling pathway responsible for CHS induction. PMID:24591052

Evaluating nurse plants for restoring native woody species to degraded subtropical woodlands.

PubMed

Yelenik, Stephanie G; DiManno, Nicole; D'Antonio, Carla M

2015-01-01

Harsh habitats dominated by invasive species are difficult to restore. Invasive grasses in arid environments slow succession toward more desired composition, yet grass removal exacerbates high light and temperature, making the use of "nurse plants" an appealing strategy. In this study of degraded subtropical woodlands dominated by alien grasses in Hawai'i, we evaluated whether individuals of two native (Dodonaea viscosa, Leptocophylla tameiameia) and one non-native (Morella faya) woody species (1) act as natural nodes of recruitment for native woody species and (2) can be used to enhance survivorship of outplanted native woody species. To address these questions, we quantified the presence and persistence of seedlings naturally recruiting beneath adult nurse shrubs and compared survival and growth of experimentally outplanted seedlings of seven native woody species under the nurse species compared to intact and cleared alien-grass plots. We found that the two native nurse shrubs recruit their own offspring, but do not act as establishment nodes for other species. Morella faya recruited even fewer seedlings than native shrubs. Thus, outplanting will be necessary to increase abundance and diversity of native woody species. Outplant survival was the highest under shrubs compared to away from them with few differences between nurse species. The worst habitat for native seedling survival and growth was within the unmanaged invasive grass matrix. Although the two native nurse species did not differentially affect outplant survival, D. viscosa is the most widespread and easily propagated and is thus more likely to be useful as an initial nurse species. The outplanted species showed variable responses to nurse habitats that we attribute to resource requirements resulting from their typical successional stage and nitrogen fixation capability.

Antioxidant Enzyme Activities and Secondary Metabolite Profiling of Oil Palm Seedlings Treated with Combination of NPK Fertilizers Infected with Ganoderma boninense.

PubMed

Sahebi, Mahbod; Hanafi, Mohamed M; Mohidin, Hasmah; Rafii, M Y; Azizi, Parisa; Idris, Abu Seman; Fariz, A; Abiri, Rambod; Taheri, Sima; Moradpoor, Mehdi

2018-01-01

Oil palm ( Elaeis guineensis Jacq) is one of the major sources of edible oil. Reducing the effect of Ganoderma, main cause of basal stem rot (BSR) on oil palm, is the main propose of this study. Understanding the oil palm defense mechanism against Ganoderma infection through monitoring changes in the secondary metabolite compounds levels before/after infection by Ganoderma under different fertilizing treatment is required. Oil palm requires macro- and microelements for growth and yield. Manipulating the nutrient for oil palm is a method to control the disease. The 3-4-month-old oil palm seedlings were given different macronutrient treatments to evaluate induction of defense related enzymes and production of secondary metabolite compounds in response to G. boninense inoculation. The observed trend of changes in the infected and uninfected seedlings was a slightly higher activity for β -1,3-glucanases, chitinase, peroxidase, and phenylalanine ammonia-lyase during the process of pathogenesis. It was found that PR proteins gave positive response to the interaction between oil palm seedlings and Ganoderma infection. Although the responses were activated systematically, they were short-lasting as the changes in enzymes activities appeared before the occurrence of visible symptoms. Effect of different nutrients doses was obviously observed among the results of the secondary metabolite compounds. Many identified/unidentified metabolite compounds were presented, of which some were involved in plant cell defense mechanism against pathogens, mostly belonging to alkaloids with bitter-tasting nitrogenous-compounds, and some had the potential to be used as new markers to detect basal stem rot at the initial step of disease.

Novel software for analysis of root gravitropism: comparative response patterns of Arabidopsis wild-type and axr1 seedlings

NASA Technical Reports Server (NTRS)

Ishikawa, H.; Evans, M. L.

1997-01-01

In an earlier study (Evans, Ishikawa & Estelle 1994, Planta 194, 215-222) we used a video digitizer system to compare the kinetics of auxin action on root elongation in wild-type seedlings and seedlings of auxin response mutants of Arabidopsis thaliana (L.) Heynh. We have since modified the system software to allow determination of elongation on opposite sides of vertical or gravistimulated roots and to allow continuous measurement of the angle of orientation of sequential subsections of the root during the response. We used this technology to compare the patterns of differential growth that generate curvature in roots of the Columbia ecotype and in the mutants axr1-3, axr1-12 and axr2, which show reduced gravitropic responsiveness and reduced sensitivity to inhibition by auxin. The pattern of differential growth during gravitropism differed in roots of wild-type and axr1 seedlings. In wild-type roots, initial curvature resulted from differential inhibition of elongation in the distal elongation zone (DEZ). This was followed by an acceleration of elongation along the top side of the DEZ. In roots of axr1-3, curvature resulted from differential stimulation of elongation whereas in roots of axr1-12 the response was variable. Roots of axr2 did not exhibit gravitropic curvature. The observation that the pattern of differential growth causing curvature is dramatically altered by a change in sensitivity to auxin is consistent with the classical Cholodny-Went theory of gravitropism which maintains that differential growth patterns induced by gravistimulation are mediated primarily by gravi-induced shifts in auxin distribution. The new technology introduced with this report allows automated determination of stimulus response patterns in the small but experimentally popular roots of Arabidopsis.

Sudden changes in environmental conditions do not increase invasion risk in grassland

NASA Astrophysics Data System (ADS)

Ruprecht, Eszter; Fenesi, Annamária; Nijs, Ivan

2013-02-01

After direct habitat transformation, biological invasions are considered to be the second most important threat to biodiversity. A better understanding of the factors affecting invasion success in new areas is crucial, and may provide insight into potential control actions. We hypothesized that invasion risk increases in habitats undergoing a sudden change in the disturbance regime or environmental conditions. For testing this assumption we initiated a seed sowing experiment while introducing two novel treatments, mowing twice and fertilizer application, in two grassland sites (one dryer and one mesic) in Romania. The seeds of two invasive species, Solidago canadensis and Rudbeckia laciniata, and two resident natives of similar seed sizes, life-forms and strategies were sowed in treated and control plots, and seed germination, seedling establishment and growth were followed during four months. Contrary to our expectations, there was no difference in the treatment effects on seed germination and seedling establishment between species, while there was on seedling vigour of the larger seeded species in the dryer grassland site, where the native had a higher performance especially in increased nutrient conditions. Indifferently from applied treatments, invasive species had greater cumulative germination in the mesic site, while natives were far more successful in seedling establishment in the drier site. At the same time, seed size was found to be a very important factor explaining germination and establishment success, with large seeded species outperforming small seeded species in any circumstances. Our results call the attention upon management interventions in mesic, productive grassland sites opening colonization windows for the recruitment of those invasive species of which ecological requirements correspond to local environmental conditions.

Antioxidant Enzyme Activities and Secondary Metabolite Profiling of Oil Palm Seedlings Treated with Combination of NPK Fertilizers Infected with Ganoderma boninense

PubMed Central

Mohidin, Hasmah; Idris, Abu Seman; Fariz, A.; Abiri, Rambod; Taheri, Sima; Moradpoor, Mehdi

2018-01-01

Oil palm (Elaeis guineensis Jacq) is one of the major sources of edible oil. Reducing the effect of Ganoderma, main cause of basal stem rot (BSR) on oil palm, is the main propose of this study. Understanding the oil palm defense mechanism against Ganoderma infection through monitoring changes in the secondary metabolite compounds levels before/after infection by Ganoderma under different fertilizing treatment is required. Oil palm requires macro- and microelements for growth and yield. Manipulating the nutrient for oil palm is a method to control the disease. The 3-4-month-old oil palm seedlings were given different macronutrient treatments to evaluate induction of defense related enzymes and production of secondary metabolite compounds in response to G. boninense inoculation. The observed trend of changes in the infected and uninfected seedlings was a slightly higher activity for β-1,3-glucanases, chitinase, peroxidase, and phenylalanine ammonia-lyase during the process of pathogenesis. It was found that PR proteins gave positive response to the interaction between oil palm seedlings and Ganoderma infection. Although the responses were activated systematically, they were short-lasting as the changes in enzymes activities appeared before the occurrence of visible symptoms. Effect of different nutrients doses was obviously observed among the results of the secondary metabolite compounds. Many identified/unidentified metabolite compounds were presented, of which some were involved in plant cell defense mechanism against pathogens, mostly belonging to alkaloids with bitter-tasting nitrogenous-compounds, and some had the potential to be used as new markers to detect basal stem rot at the initial step of disease. PMID:29721500

Evaluating nurse plants for restoring native woody species to degraded subtropical woodlands

USGS Publications Warehouse

Yelenik, Stephanie G.; DiManno, Nicole; D’Antonio, Carla M.

2015-01-01

Harsh habitats dominated by invasive species are difficult to restore. Invasive grasses in arid environments slow succession toward more desired composition, yet grass removal exacerbates high light and temperature, making the use of “nurse plants” an appealing strategy. In this study of degraded subtropical woodlands dominated by alien grasses in Hawai'i, we evaluated whether individuals of two native (Dodonaea viscosa, Leptocophylla tameiameia) and one non-native (Morella faya) woody species (1) act as natural nodes of recruitment for native woody species and (2) can be used to enhance survivorship of outplanted native woody species. To address these questions, we quantified the presence and persistence of seedlings naturally recruiting beneath adult nurse shrubs and compared survival and growth of experimentally outplanted seedlings of seven native woody species under the nurse species compared to intact and cleared alien-grass plots. We found that the two native nurse shrubs recruit their own offspring, but do not act as establishment nodes for other species. Morella faya recruited even fewer seedlings than native shrubs. Thus, outplanting will be necessary to increase abundance and diversity of native woody species. Outplant survival was the highest under shrubs compared to away from them with few differences between nurse species. The worst habitat for native seedling survival and growth was within the unmanaged invasive grass matrix. Although the two native nurse species did not differentially affect outplant survival, D. viscosa is the most widespread and easily propagated and is thus more likely to be useful as an initial nurse species. The outplanted species showed variable responses to nurse habitats that we attribute to resource requirements resulting from their typical successional stage and nitrogen fixation capability.

Effects of seed mass on seedling success in Artocarpus heterophyllus L., a tropical tree species of north-east India

NASA Astrophysics Data System (ADS)

Khan, M. L.

2004-03-01

I examined the effects of seed mass on performance of seedlings of Artocarpus heterophyllus L. (Moraceae), a large evergreen late successional shade-tolerant tree species in three contrasting light conditions. Seed mass varied many fold from 1.5 to 14 g in A. heterophyllus. Germination and germination time showed a significant correlation with seed mass. Germination differed significantly among three light regimes (50%, 25% and 3%). Seed mass and light level significantly affected seedling survival. The seedlings that emerged from large seeds survived better than those from small seeds under all light regimes. Survival of seedlings was maximum in 25% light regime for all seed mass classes but did not differ significantly from that at 50% light regime. Survival was significantly lower in 3% light as compared to 50% and 25% light regimes. Seedling vigor (expressed in terms of seedling height, leaf area and dry weight) was also significantly affected by seed mass and light regimes. Seedlings that emerged from larger seeds and grew under 50% light regime produced the heaviest seedlings, while those resulting from smaller seeds and grown under 3% light regime produced the lightest seedlings. Resprouting capacity of seedlings after clipping was significantly affected by seed mass and light regime. Seedlings emerging from larger seeds were capable of resprouting several times successively. Resprouting was more pronounced under 50% and 25% light regimes as compared to 3% light. Success of A. heterophyllus regeneration appears to be regulated by an interactive effect of seed mass and light regime.

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.

Chlorophyll fluorescence and CO(2) assimilation of black spruce seedlings following frost in different temperature and light conditions.

PubMed

Lamontagne, M.; Bigras, F. J.; Margolis, H. A.

2000-03-01

Effects of artificial frosts on light-saturated photosynthesis (A(max)) and ground, maximal and variable fluorescence variables (F(o), F(m), and F(v) and F(v)/F(m)) were monitored on 1-year-old foliage of black spruce seedlings (Picea mariana (Mill.) BSP) grown at high (25 degrees C), moderate (15 degrees C) and low (5 degrees C) temperatures and moderate (240 &mgr;mol m(-2) s(-1)) and low (80 &mgr;mol m(-2) s(-1)) irradiances. Photoinhibition of 1-year-old foliage was greater in seedlings grown in moderate light than in seedlings grown in low light. Photoinhibition increased with decreasing growth chamber temperature at both irradiances. Most changes in F(v)/F(m) were caused by changes in F(v). Exposure to -4 degrees C decreased both F(v)/F(m) and A(max) compared with control values. The effect of the -4 degrees C frost treatment was greater in seedlings grown in low light than in seedlings grown in moderate light, probably because seedlings grown in moderate light were already partially photoinhibited before the frost treatment. Following -4 degrees C treatment, neither F(v)/F(m) nor A(max) recovered in seedlings grown in low light. Light-saturated photosynthesis decreased with decreasing growth chamber temperature. Light-saturated photosynthesis was more sensitive to the -3 and -4 degrees C frost treatments in seedlings grown at 25 degrees C than in seedlings grown at 15 and 5 degrees C. The A(max) of seedlings grown at 15 degrees C was sensitive only to the -4 degrees C frost treatment, whereas A(max) of seedlings grown at 5 degrees C was not sensitive to any of the frost treatments. Recovery of A(max) following frost took longer in seedlings grown at high temperatures than in seedlings grown at low temperatures. For seedlings grown at the same temperature but under different irradiances, both A(max) and F(v)/F(m) reflected damage to the photosynthetic system following a moderate frost. However, for seedlings grown at the same irradiance but different temperatures, A(max) provided a more sensitive indicator of frost damage to the photosynthetic system than F(v)/F(m) ratio.

Seedling root responses to soil moisture and the identification of a belowground trait spectrum across three growth forms.

PubMed

Larson, Julie E; Funk, Jennifer L

2016-05-01

Root trait variation and plasticity could be key factors differentiating plant performance under drought. However, water manipulation and root measurements are rarely coupled empirically across growth forms to identify whether belowground strategies are generalizable across species. We measured seedling root traits across three moisture levels in 18 Mediterranean forbs, grasses, and woody species. Drought increased the root mass fraction (RMF) and decreased the relative proportion of thin roots (indicated by increased root diameters and decreased specific root length (SRL)), rates of root elongation and growth, plant nitrogen uptake, and plant growth. Although responses varied across species, plasticity was not associated with growth form. Woody species differed from forbs and grasses in many traits, but herbaceous groups were similar. Across water treatments, trait correlations suggested a single spectrum of belowground trade-offs related to resource acquisition and plant growth. While effects of SRL and RMF on plant growth shifted with drought, root elongation rate consistently represented this spectrum. We demonstrate that general patterns of root morphology and plasticity are identifiable across diverse species. Root trait measurements should enhance our understanding of belowground strategy and performance across growth forms, but it will be critical to incorporate plasticity and additional aspects of root function into these efforts. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Evaluation of indigenous bacterial strains for biocontrol of the frogeye leaf spot of soya bean caused by Cercospora sojina.

PubMed

Simonetti, E; Carmona, M A; Scandiani, M M; García, A F; Luque, A G; Correa, O S; Balestrasse, K B

2012-08-01

Assessment of biological control of Cercospora sojina, causal agent of frogeye leaf spot (FLS) of soya bean, using three indigenous bacterial strains, BNM297 (Pseudomonas fluorescens), BNM340 and BNM122 (Bacillus amyloliquefaciens). From cultures of each bacterial strain, cell suspensions and cell-free supernatants were obtained and assayed to determine their antifungal activity against C. sojina. Both mycelial growth and spore germination in vitro were more strongly inhibited by bacterial cell suspensions than by cell-free supernatants. The Bacillus strains BNM122 and BNM340 inhibited the fungal growth to a similar degree (I ≈ 52-53%), while cells from P. fluorescens BNM297 caused a lesser reduction (I ≈ 32-34%) in the fungus colony diameter. The foliar application of the two Bacillus strains on soya bean seedlings, under greenhouse conditions, significantly reduced the disease severity with respect to control soya bean seedlings and those sprayed with BNM297. This last bacterial strain was not effective in controlling FLS in vivo. Our data demonstrate that the application of antagonistic bacteria may be a promising and environmentally friendly alternative to control the FLS of soya bean.   To our knowledge, this is the first report of biological control of C. sojina by using native Bacillus strains. © 2012 The Authors. Letters in Applied Microbiology © 2012 The Society for Applied Microbiology.

Nanoscale Zinc Oxide Particles for Improving the Physiological and Sanitary Quality of a Mexican Landrace of Red Maize

PubMed Central

Estrada-Urbina, Juan; Cruz-Alonso, Alejandro; Santander-González, Martha; Vázquez-Durán, Alma

2018-01-01

In this research, quasi-spherical-shaped zinc oxide nanoparticles (ZnO NPs) were synthesized by a simple cost-competitive aqueous precipitation method. The engineered NPs were characterized using several validation methodologies: UV–Vis spectroscopy, diffuse reflection UV–Vis, spectrofluorometry, transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Fourier transform infrared (FTIR) spectroscopy with attenuated total reflection (ATR). A procedure was established to coat a landrace of red maize using gelatinized maize starch. Each maize seed was treated with 0.16 mg ZnO NPs (~7.7 × 109 particles). The standard germination (SG) and accelerated aging (AA) tests indicated that ZnO NP-treated maize seeds presented better physiological quality (higher percentage of normal seedlings) and sanitary quality (lower percentage of seeds contaminated by microorganisms) as compared to controls. The application of ZnO NPs also improved seedling vigor, correlated to shoot length, shoot diameter, root length, and number of secondary roots. Furthermore, shoots and roots of the ZnO NP-treated maize seeds showed a marked increment in the main active FTIR band areas, most notably for the vibrations associated with peptide-protein, lipid, lignin, polysaccharide, hemicellulose, cellulose, and carbohydrate. From these results, it is concluded that ZnO NPs have potential for applications in peasant agriculture to improve the quality of small-scale farmers’ seeds and, as a result, preserve germplasm resources. PMID:29673162

A diameter increment model for Red Fir in California and Southern Oregon

Treesearch

K. Leroy Dolph

1992-01-01

Periodic (10-year) diameter increment of individual red fir trees in Califomia and southern Oregon can be predicted from initial diameter and crown ratio of each tree, site index, percent slope, and aspect of the site. The model actually predicts the natural logarithm ofthe change in squared diameter inside bark between the startand the end of a 10-year growth period....

Effects of local biotic neighbors and habitat heterogeneity on tree and shrub seedling survival in an old-growth temperate forest.

PubMed

Bai, Xuejiao; Queenborough, Simon A; Wang, Xugao; Zhang, Jian; Li, Buhang; Yuan, Zuoqiang; Xing, Dingliang; Lin, Fei; Ye, Ji; Hao, Zhanqing

2012-11-01

Seedling dynamics play a crucial role in determining species distributions and coexistence. Exploring causes of variation in seedling dynamics can therefore provide key insights into the factors affecting these phenomena. We examined the relative importance of biotic neighborhood processes and habitat heterogeneity using survival data for 5,827 seedlings in 39 tree and shrub species over 2 years from an old-growth temperate forest in northeastern China. We found significant negative density-dependence effects on survival of tree seedlings, and limited effects of habitat heterogeneity (edaphic and topographic variables) on survival of shrub seedlings. The importance of negative density dependence on young tree seedling survival was replaced by habitat in tree seedlings ≥ 4 years old. As expected, negative density dependence was more apparent in gravity-dispersed species compared to wind-dispersed and animal-dispersed species. Moreover, we found that a community compensatory trend existed for trees. Therefore, although negative density dependence was not as pervasive as in other forest communities, it is an important mechanism for the maintenance of community diversity in this temperate forest. We conclude that both negative density dependence and habitat heterogeneity drive seedling survival, but their relative importance varies with seedling age classes and species traits.

Allocation strategies of savanna and forest tree seedlings in response to fire and shading: outcomes of a field experiment

NASA Astrophysics Data System (ADS)

Gignoux, Jacques; Konaté, Souleymane; Lahoreau, Gaëlle; Le Roux, Xavier; Simioni, Guillaume

2016-12-01

The forest-savanna ecotone may be very sharp in fire-prone areas. Fire and competition for light play key roles in its maintenance, as forest and savanna tree seedlings are quickly excluded from the other ecosystem. We hypothesized a tradeoff between seedling traits linked to fire resistance and to competition for light to explain these exclusions. We compared growth- and survival-related traits of two savanna and two forest species in response to shading and fire in a field experiment. To interpret the results, we decomposed our broad hypothesis into elementary tradeoffs linked to three constraints, biomass allocation, plant architecture, and shade tolerance, that characterize both savanna and adjacent forest ecosystems. All seedlings reached similar biomasses, but forest seedlings grew taller. Savanna seedlings better survived fire after topkill and required ten times less biomass than forest seedlings to survive. Finally, only savanna seedlings responded to shading. Although results were consistent with the classification of our species as mostly adapted to shade tolerance, competition for light in the open, and fire tolerance, they raised new questions: how could savanna seedlings survive better with a 10-times lower biomass than forest seedlings? Is their shade intolerance sufficient to exclude them from forest understory?

Common arbuscular mycorrhizal networks amplify competition for phosphorus between seedlings and established plants.

PubMed

Merrild, Marie P; Ambus, Per; Rosendahl, Søren; Jakobsen, Iver

2013-10-01

Common mycorrhizal networks (CMNs) influence competition between plants, but reports regarding their precise effect are conflicting. We studied CMN effects on phosphorus (P) uptake and growth of seedlings as influenced by various disruptions of network components. Tomato (Solanum lycopersicon) seedlings grew into established networks of Rhizophagus irregularis and cucumber (Cucumis sativus) in two experiments. One experiment studied seedling uptake of (32)P in the network in response to cutting of cucumber shoots; the other analysed seedling uptake of P and nitrogen (N) in the presence of intact or severed arbuscular mycorrhizal fungus networks and at two soil P concentrations. Pre-established and intact networks suppressed growth of tomato seedlings. Cutting of cucumber shoots mitigated P deficiency symptoms of seedlings, which obtained access to P in the extraradical mycelium and thereby showed improved growth. Solitary seedlings growing in a network patch that had been severed from the CMN also grew much better than seedlings of the corresponding CMN. Interspecific and size-asymmetric competition between plants may be amplified rather than relaxed by CMNs that transfer P to large plants providing most carbon and render small plants P deficient. It is likely that grazing or senescence of the large plants will alleviate the network-induced suppression of seedling growth. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

A Biocontrol Strain of Bacillus subtilis WXCDD105 Used to Control Tomato Botrytis cinerea and Cladosporium fulvum Cooke and Promote the Growth of Seedlings

PubMed Central

Wang, Hui; Shi, Yuying; Wang, Doudou; Yao, Zhongtong; Wang, Yimei; Liu, Jiayin; Zhang, Shumei; Wang, Aoxue

2018-01-01

In this study, a strain named WXCDD105, which has strong antagonistic effects on Botrytis cinerea and Cladosporium fulvum Cooke, was screened out from the rhizosphere of healthy tomato plants. The tomato plants had inhibition diameter zones of 5.00 mm during the dual culture for four days. Based on the morphological and physiological characteristics, the 16S rDNA sequence, and the gyrB gene sequence analysis, the strain WXCDD105 was identified as Bacillus subtilis suBap. subtilis. The results of the mycelial growth test showed that the sterile filtrate of the strain WXCDD105 could significantly inhibit mycelial growth of Botrytis cinerea and Cladosporium fulvum Cooke. The inhibition rates were 95.28 and 94.44%, respectively. The potting experiment showed that the strain WXCDD105 made effective the control of tomato gray mold and tomato leaf mold. The control efficiencies were 74.70 and 72.07%. The antagonistic test results showed that the strain WXCDD105 had different degrees of inhibition on 10 kinds of plant pathogenic fungi and the average inhibition rates were more than 80%. We also found that the strain WXCDD105 stimulated both the seed germination and seedling growth of tomatoes. Using the fermentation liquid of WXCDD105 (108 cfu·mL−1) to treat the seeds, the germination rate and radicle length were increased. Under the treatment of the fermentation liquid of the strain WXCDD105 (106 cfu·mL−1), nearly all physiological indexes of tomato seedlings were significantly higher than that of the control groups. This could not only keep the nutritional quality of tomato fruits but also prevent them from rotting. This study provided us with an excellent strain for biological control of tomato gray mold, tomato leaf mold, and tomato growth promotion. This also laid the technical foundation for its application. PMID:29734678

Arbuscular Mycorrhizal Fungus Species Dependency Governs Better Plant Physiological Characteristics and Leaf Quality of Mulberry (Morus alba L.) Seedlings

PubMed Central

Shi, Song-Mei; Chen, Ke; Gao, Yuan; Liu, Bei; Yang, Xiao-Hong; Huang, Xian-Zhi; Liu, Gui-Xi; Zhu, Li-Quan; He, Xin-Hua

2016-01-01

Understanding the synergic interactions between arbuscular mycorrhizal fungi (AMF) and its host mulberry (Morus alba L.), an important perennial multipurpose plant, has theoretical and practical significance in mulberry plantation, silkworm cultivation, and relevant textile industry. In a greenhouse study, we compared functional distinctions of three genetically different AMF species (Acaulospora scrobiculata, Funneliformis mosseae, and Rhizophagus intraradices) on physiological and growth characteristics as well as leaf quality of 6-month-old mulberry seedlings. Results showed that mulberry was AMF-species dependent, and AMF colonization significantly increased shoot height and taproot length, stem base and taproot diameter, leaf and fibrous root numbers, and shoot and root biomass production. Meanwhile, leaf chlorophyll a or b and carotenoid concentrations, net photosynthetic rate, transpiration rate and stomatal conductance were generally significantly greater, while intercellular CO2 concentration was significantly lower in AMF-inoculated seedlings than in non-AMF-inoculated counterparts. These trends were also generally true for leaf moisture, total nitrogen, all essential amino acids, histidine, proline, soluble protein, sugar, and fatty acid as they were significantly increased under mycorrhization. Among these three tested AMFs, significantly greater effects of AMF on above-mentioned mulberry physiological and growth characteristics ranked as F. mosseae > A. scrobiculata > R. intraradices, whilst on mulberry leaf quality (e.g., nutraceutical values) for better silkworm growth as F. mosseae ≈A. scrobiculata > R. intraradices. In conclusion, our results showed that greater mulberry biomass production, and nutritional quality varied with AMF species or was AMF-species dependent. Such improvements were mainly attributed to AMF-induced positive alterations of mulberry leaf photosynthetic pigments, net photosynthetic rate, transpiration rate, and N-containing compounds (methionine, threonine, histidine, and proline). As a result, application of Funneliformis mosseae or A. scrobiculata in mulberry plantation could be a promising management strategy to promote silkworm cultivation and relevant textile industry. PMID:27446063

Arbuscular Mycorrhizal Fungus Species Dependency Governs Better Plant Physiological Characteristics and Leaf Quality of Mulberry (Morus alba L.) Seedlings.

PubMed

Shi, Song-Mei; Chen, Ke; Gao, Yuan; Liu, Bei; Yang, Xiao-Hong; Huang, Xian-Zhi; Liu, Gui-Xi; Zhu, Li-Quan; He, Xin-Hua

2016-01-01

Understanding the synergic interactions between arbuscular mycorrhizal fungi (AMF) and its host mulberry (Morus alba L.), an important perennial multipurpose plant, has theoretical and practical significance in mulberry plantation, silkworm cultivation, and relevant textile industry. In a greenhouse study, we compared functional distinctions of three genetically different AMF species (Acaulospora scrobiculata, Funneliformis mosseae, and Rhizophagus intraradices) on physiological and growth characteristics as well as leaf quality of 6-month-old mulberry seedlings. Results showed that mulberry was AMF-species dependent, and AMF colonization significantly increased shoot height and taproot length, stem base and taproot diameter, leaf and fibrous root numbers, and shoot and root biomass production. Meanwhile, leaf chlorophyll a or b and carotenoid concentrations, net photosynthetic rate, transpiration rate and stomatal conductance were generally significantly greater, while intercellular CO2 concentration was significantly lower in AMF-inoculated seedlings than in non-AMF-inoculated counterparts. These trends were also generally true for leaf moisture, total nitrogen, all essential amino acids, histidine, proline, soluble protein, sugar, and fatty acid as they were significantly increased under mycorrhization. Among these three tested AMFs, significantly greater effects of AMF on above-mentioned mulberry physiological and growth characteristics ranked as F. mosseae > A. scrobiculata > R. intraradices, whilst on mulberry leaf quality (e.g., nutraceutical values) for better silkworm growth as F. mosseae ≈A. scrobiculata > R. intraradices. In conclusion, our results showed that greater mulberry biomass production, and nutritional quality varied with AMF species or was AMF-species dependent. Such improvements were mainly attributed to AMF-induced positive alterations of mulberry leaf photosynthetic pigments, net photosynthetic rate, transpiration rate, and N-containing compounds (methionine, threonine, histidine, and proline). As a result, application of Funneliformis mosseae or A. scrobiculata in mulberry plantation could be a promising management strategy to promote silkworm cultivation and relevant textile industry.

A Biocontrol Strain of Bacillus subtilis WXCDD105 Used to Control Tomato Botrytis cinerea and Cladosporium fulvum Cooke and Promote the Growth of Seedlings.

PubMed

Wang, Hui; Shi, Yuying; Wang, Doudou; Yao, Zhongtong; Wang, Yimei; Liu, Jiayin; Zhang, Shumei; Wang, Aoxue

2018-05-04

In this study, a strain named WXCDD105, which has strong antagonistic effects on Botrytis cinerea and Cladosporium fulvum Cooke, was screened out from the rhizosphere of healthy tomato plants. The tomato plants had inhibition diameter zones of 5.00 mm during the dual culture for four days. Based on the morphological and physiological characteristics, the 16S rDNA sequence, and the gyrB gene sequence analysis, the strain WXCDD105 was identified as Bacillus subtilis suBap. subtilis . The results of the mycelial growth test showed that the sterile filtrate of the strain WXCDD105 could significantly inhibit mycelial growth of Botrytis cinerea and Cladosporium fulvum Cooke. The inhibition rates were 95.28 and 94.44%, respectively. The potting experiment showed that the strain WXCDD105 made effective the control of tomato gray mold and tomato leaf mold. The control efficiencies were 74.70 and 72.07%. The antagonistic test results showed that the strain WXCDD105 had different degrees of inhibition on 10 kinds of plant pathogenic fungi and the average inhibition rates were more than 80%. We also found that the strain WXCDD105 stimulated both the seed germination and seedling growth of tomatoes. Using the fermentation liquid of WXCDD105 (10⁸ cfu·mL −1 ) to treat the seeds, the germination rate and radicle length were increased. Under the treatment of the fermentation liquid of the strain WXCDD105 (10⁶ cfu·mL −1 ), nearly all physiological indexes of tomato seedlings were significantly higher than that of the control groups. This could not only keep the nutritional quality of tomato fruits but also prevent them from rotting. This study provided us with an excellent strain for biological control of tomato gray mold, tomato leaf mold, and tomato growth promotion. This also laid the technical foundation for its application.

Modeling of genetic gain for single traits from marker-assisted seedling selection in clonally propagated crops

PubMed Central

Ru, Sushan; Hardner, Craig; Carter, Patrick A; Evans, Kate; Main, Dorrie; Peace, Cameron

2016-01-01

Seedling selection identifies superior seedlings as candidate cultivars based on predicted genetic potential for traits of interest. Traditionally, genetic potential is determined by phenotypic evaluation. With the availability of DNA tests for some agronomically important traits, breeders have the opportunity to include DNA information in their seedling selection operations—known as marker-assisted seedling selection. A major challenge in deploying marker-assisted seedling selection in clonally propagated crops is a lack of knowledge in genetic gain achievable from alternative strategies. Existing models based on additive effects considering seed-propagated crops are not directly relevant for seedling selection of clonally propagated crops, as clonal propagation captures all genetic effects, not just additive. This study modeled genetic gain from traditional and various marker-based seedling selection strategies on a single trait basis through analytical derivation and stochastic simulation, based on a generalized seedling selection scheme of clonally propagated crops. Various trait-test scenarios with a range of broad-sense heritability and proportion of genotypic variance explained by DNA markers were simulated for two populations with different segregation patterns. Both derived and simulated results indicated that marker-based strategies tended to achieve higher genetic gain than phenotypic seedling selection for a trait where the proportion of genotypic variance explained by marker information was greater than the broad-sense heritability. Results from this study provides guidance in optimizing genetic gain from seedling selection for single traits where DNA tests providing marker information are available. PMID:27148453

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.

Effect of canopy position on germination and seedling survival of epiphytic bromeliads in a Mexican humid montane forest.

PubMed

Winkler, Manuela; Hülber, Karl; Hietz, Peter

2005-05-01

Seeds of epiphytes must land on branches with suitable substrates and microclimates to germinate and for the resulting seedlings to survive. It is important to understand the fate of seeds and seedlings in order to model populations, but this is often neglected when only established plants are included in analyses. The seeds of five bromeliad species were exposed to different canopy positions in a Mexican montane forest, and germination and early seedling survival were recorded. Additionally, the survival of naturally dispersed seedlings was monitored in a census over 2.5 years. Survival analysis, a procedure rarely used in plant ecology, was used to study the influence of branch characteristics and light on germination and seedling survival in natural and experimental populations. Experimental germination percentages ranged from 7.2 % in Tillandsia deppeana to 33.7 % in T. juncea, but the seeds of T. multicaulis largely failed to germinate. Twenty months after exposure between 3.5 and 9.4 % of the seedlings were still alive. There was no evidence that canopy position affected the probability of germination, but time to germination was shorter in less exposed canopy positions indicating that higher humidity accelerates germination. More experimental seedlings survived when canopy openness was high, whereas survival in census-seedlings was influenced by moss cover. While mortality decreased steadily with age in juveniles of the atmospheric Tillandsia, in the more mesomorphic Catopsis sessiliflora mortality increased dramatically in the dry season. Seedling mortality, rather than the failure to germinate, accounts for the differential distribution of epiphytes within the canopy studied. With few safe sites to germinate and high seedling mortality, changes of local climate may affect epiphyte populations primarily through their seedling stage.

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.

Low power continuous wave-laser seed irradiation effect on Moringa oleifera germination, seedling growth and biochemical attributes.

PubMed

Urva; Shafique, Hina; Jamil, Yasir; Haq, Zia Ul; Mujahid, Tamveel; Khan, Aman Ullah; Iqbal, Munawar; Abbas, Mazhar

2017-05-01

Recently, laser application in agriculture has gained much attention since plant characteristics were improved significantly in response of pre-sowing seed treatment. Pre-sowing laser seed treatment effects on germination, seedling growth and mineral profile were studied in Moringa olifera. M. olifera healthy seeds were exposed to 25, 50, 75mJ low power continuous wave laser light and grown under greenhouse conditions. The seedling growth and biochemical attributes were evaluated from 10-day-old seedlings. The germination parameters (percentage, mean germination time), vigor index, seedling growth (root length, seedling length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight) enhanced considerably. The laser energy levels used for seed irradiation showed variable effects on germination, seedling growth and mineral profile. The mineral contents were recorded to be higher in seedling raised from laser treated seeds, which were higher in roots versus shoots and leaves. The effect of laser treatment on seedling fat, nitrogen and protein content was insignificant and at higher energy level both nitrogen and protein contents decreased versus control. Results revealed that M. olifera germination, seedling growth and mineral contents were enhanced and optimum laser energy level has more acceleratory effect since at three laser energy levels the responses were significantly different. Overall the laser energy levels effect on germination and seedling growth was found in following order; 75mJ>50mJ>25mJ, where as in case of fat, protein and nitrogen contents the trend was as; 25mJ>50mJ and 75mJ. However, this technique could possibly be used to improve the M. olifera germination, seedling growth, and minerals contents where germination is low due to unfavorable conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Biological effects of carbon nanotubes generated in forest wildfire ecosystems rich in resinous trees on native plants

PubMed Central

Dasgupta-Schubert, Nabanita; Borjas-García, Salomón; Tiwari, DK; Paraguay-Delgado, Francisco; Jiménez-Sandoval, Sergio; Alonso-Nuñez, Gabriel; Gómez-Romero, Mariela; Lindig-Cisneros, Roberto; Reyes De la Cruz, Homero

2017-01-01

Carbon nanotubes (CNTs) have a broad range of applications and are generally considered human-engineered nanomaterials. However, carbon nanostructures have been found in ice cores and oil wells, suggesting that nature may provide appropriate conditions for CNT synthesis. During forest wildfires, materials such as turpentine and conifer tissues containing iron under high temperatures may create chemical conditions favorable for CNT generation, similar to those in synthetic methods. Here, we show evidence of naturally occurring multiwalled carbon nanotubes (MWCNTs) produced from Pinus oocarpa and Pinus pseudostrobus, following a forest wildfire. The MWCNTs showed an average of 10 walls, with internal diameters of ∼2.5 nm and outer diameters of ∼14.5 nm. To verify whether MWCNT generation during forest wildfires has a biological effect on some characteristic plant species of these ecosystems, germination and development of seedlings were conducted. Results show that the utilization of comparable synthetic MWCNTs increased seed germination rates and the development of Lupinus elegans and Eysenhardtia polystachya, two plants species found in the burned forest ecosystem. The finding provides evidence that supports the generation and possible ecological functions of MWCNTs in nature. PMID:28828256

Biological effects of carbon nanotubes generated in forest wildfire ecosystems rich in resinous trees on native plants.

PubMed

Lara-Romero, Javier; Campos-García, Jesús; Dasgupta-Schubert, Nabanita; Borjas-García, Salomón; Tiwari, D K; Paraguay-Delgado, Francisco; Jiménez-Sandoval, Sergio; Alonso-Nuñez, Gabriel; Gómez-Romero, Mariela; Lindig-Cisneros, Roberto; Reyes De la Cruz, Homero; Villegas, Javier A

2017-01-01

Carbon nanotubes (CNTs) have a broad range of applications and are generally considered human-engineered nanomaterials. However, carbon nanostructures have been found in ice cores and oil wells, suggesting that nature may provide appropriate conditions for CNT synthesis. During forest wildfires, materials such as turpentine and conifer tissues containing iron under high temperatures may create chemical conditions favorable for CNT generation, similar to those in synthetic methods. Here, we show evidence of naturally occurring multiwalled carbon nanotubes (MWCNTs) produced from Pinus oocarpa and Pinus pseudostrobus, following a forest wildfire. The MWCNTs showed an average of 10 walls, with internal diameters of ∼2.5 nm and outer diameters of ∼14.5 nm. To verify whether MWCNT generation during forest wildfires has a biological effect on some characteristic plant species of these ecosystems, germination and development of seedlings were conducted. Results show that the utilization of comparable synthetic MWCNTs increased seed germination rates and the development of Lupinus elegans and Eysenhardtia polystachya , two plants species found in the burned forest ecosystem. The finding provides evidence that supports the generation and possible ecological functions of MWCNTs in nature.

Effect of Gamma Rays on Sophora davidii and Detection of DNA Polymorphism through ISSR Marker

PubMed Central

Wang, Puchang; Mo, Bentian; Luo, Tianqiong

2017-01-01

Sophora davidii (Franch.) Kom. ex Pavol is an important medicinal plant and a feeding scrub with ecological value. The effects of different gamma irradiation doses (20–140 Kr) on seed germination and seedling morphology were investigated in S. davidii, and intersimple sequence repeat (ISSR) markers were used to identify the DNA polymorphism among mutants. Significant variations were observed for seed germination, stem diameter, and number of branches per plant. The improved agronomic traits, such as stem diameter and number of branches per plant, were recorded at 80 Kr dose and 20 Kr dose for seed germination. ISSR analysis generated in total 183 scorable fragments, of which 94 (51.37%) were polymorphic. The percentage of polymorphism ranged from 14.29 to 93.33 with an average of 45.69%. Jaccard's coefficients of dissimilarity varied from 0.6885 to 1.000, indicative of the level of genetic variation among the mutants. The constructed dendrogram grouped the entities into five clusters. Consequently, it was concluded that gamma rays irradiation of seeds generates a sufficient number of induced mutations and that ISSR analysis offered a useful molecular marker for the identification of mutants. PMID:28612030

Light Affects the Chloroplast Ultrastructure and Post-Storage Photosynthetic Performance of Watermelon (Citrullus lanatus) Plug Seedlings

PubMed Central

Duan, Qingqing; Jiang, Wu; Ding, Ming; Lin, Ye; Huang, Danfeng

2014-01-01

Watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] plug seedlings were stored at 15°C in the light at a photosynthetic photon flux density of 15 µmol·m−2·s−1 or in darkness for 6 days, to evaluate their chloroplast ultrastructure, and associated photosynthetic characteristics. Storage in the dark caused swelling, disordered granal arrangement, and starch grain disappearance in the chloroplasts. In contrast, the chloroplasts stored in the light were relatively normal. As a result, the light-stored seedlings had a significantly higher chlorophyll content, Fv/Fm, and Pn than did dark-stored seedlings. Regardless of whether the seedlings were stored in light or darkness, the Gs and Ls of the seedlings significantly decreased, while the Ci obviously increased when the Pn decreased after 6 days of storage. This result suggests that the decreased Pn is not solely a stomatal effect, as the effects on the chloroplasts contributed to this photosynthetic inhibition. Six days after transplanting, seedlings that were stored in the light or darkness for 2 or 4 days showed complete recovery of chloroplast ultrastructure, chlorophyll content, Fv/Fm, Gs and Pn. When the storage period increased to 6 days, the dark-stored seedlings had a significantly lower Fv/Fm and Pn than the light-stored and control seedlings 6 days after transplanting, which was mainly ascribed to incomplete recovery of chloroplast ultrastructure. Furthermore, the light-stored seedlings exhibited a significantly higher shoot dry weight during storage and a higher percentage dry weight increase after transplanting than the dark-stored seedlings. These effects were enhanced by prolonged storage (4 to 6 days). This study demonstrated that dim light during storage is beneficial for maintaining chloroplast ultrastructure as well as photosynthetic efficiency in watermelon seedlings, thus contributing to the rapid recovery of post-storage photosynthetic performance, which ensures the transplant quality of the seedlings after removal from storage. PMID:25340859

Numerical and analytical simulation of the production process of ZrO2 hollow particles

NASA Astrophysics Data System (ADS)

Safaei, Hadi; Emami, Mohsen Davazdah

2017-12-01

In this paper, the production process of hollow particles from the agglomerated particles is addressed analytically and numerically. The important parameters affecting this process, in particular, the initial porosity level of particles and the plasma gun types are investigated. The analytical model adopts a combination of quasi-steady thermal equilibrium and mechanical balance. In the analytical model, the possibility of a solid core existing in agglomerated particles is examined. In this model, a range of particle diameters (50μm ≤ D_{p0} ≤ 160 μ m) and various initial porosities ( 0.2 ≤ p ≤ 0.7) are considered. The numerical model employs the VOF technique for two-phase compressible flows. The production process of hollow particles from the agglomerated particles is simulated, considering an initial diameter of D_{p0} = 60 μm and initial porosity of p = 0.3, p = 0.5, and p = 0.7. Simulation results of the analytical model indicate that the solid core diameter is independent of the initial porosity, whereas the thickness of the particle shell strongly depends on the initial porosity. In both models, a hollow particle may hardly develop at small initial porosity values ( p < 0.3), while the particle disintegrates at high initial porosity values ( p > 0.6.

Rocket seedling production on the international space station: Growth and nutritional properties

NASA Astrophysics Data System (ADS)

Colla, Giuseppe; Battistelli, Alberto; Proietti, Simona; Moscatello, Stefano; Rouphael, Youssef; Cardarelli, Mariateresa; Casucci, Marco

2007-09-01

Producing sprouts directly during space missions may represent an interesting opportunity to offer high-quality fresh ready to eat food to the astronauts. The goal of this work was to compare, in terms of growth and nutritional quality, rocket (Eruca sativa Mill.) seedlings grown in the International Space Station during the ENEIDE mission with those grown in a ground-based experiment (in presence and absence of clinorotation). The rocket seedlings obtained from the space-experiment were thinner and more elongated than those obtained in the ground-based experiment. Cotyledons were often closed in the seedlings grown in the space experiment. Quantitative (germination, fresh and dry weight) and qualitative (glucose, fructose, sucrose and starch) traits of rocket seedling were negatively affected by micrograv-ity, especially those recorded on seedlings grown under real microgravity conditions The total chlorophyll, and carotenoids of seedlings obtained in the space experiment were strongly reduced in comparison to those obtained in the ground-based experiment (presence and absence of clinorotation). The results showed that it is possible to produce rocket seedlings in the ISS; however, further studies are needed to define the optimal environmental conditions for producing rocket seedlings with high nutritional value

Phosphorus limits Eucalyptus grandis seedling growth in an unburnt rain forest soil

PubMed Central

Tng, David Y. P.; Janos, David P.; Jordan, Gregory J.; Weber, Ellen; Bowman, David M. J. S.

2014-01-01

Although rain forest is characterized as pyrophobic, pyrophilic giant eucalypts grow as rain forest emergents in both temperate and tropical Australia. In temperate Australia, such eucalypts depend on extensive, infrequent fires to produce conditions suitable for seedling growth. Little is known, however, about constraints on seedlings of tropical giant eucalypts. We tested whether seedlings of Eucalyptus grandis experience edaphic constraints similar to their temperate counterparts. We hypothesized that phosphorous addition would alleviate edaphic constraints. We grew seedlings in a factorial experiment combining fumigation (to simulate nutrient release and soil pasteurization by fire), soil type (E. grandis forest versus rain forest soil) and phosphorus addition as factors. We found that phosphorus was the principal factor limiting E. grandis seedling survival and growth in rain forest soil, and that fumigation enhanced survival of seedlings in both E. grandis forest and rain forest soil. We conclude that similar to edaphic constraints on temperate giant eucalypts, mineral nutrient and biotic attributes of a tropical rain forest soil may hamper E. grandis seedling establishment. In rain forest soil, E. grandis seedlings benefited from conditions akin to a fire-generated ashbed (i.e., an “ashbed effect”). PMID:25339968

Effect of Continuous Cropping Generations on Each Component Biomass of Poplar Seedlings during Different Growth Periods

PubMed Central

Xia, Jiangbao; Zhang, Shuyong; Li, Tian; Liu, Xia; Zhang, Ronghua; Zhang, Guangcan

2014-01-01

In order to investigate the change rules and response characteristics of growth status on each component of poplar seedling followed by continuous cropping generations and growth period, we clear the biomass distribution pattern of poplar seedling, adapt continuous cropping, and provide theoretical foundation and technical reference on cultivation management of poplar seedling, the first generation, second generation, and third generation continuous cropping poplar seedlings were taken as study objects, and the whole poplar seedling was harvested to measure and analyze the change of each component biomass on different growth period poplar leaves, newly emerging branches, trunks and root system, and so forth. The results showed that the whole biomass of poplar seedling decreased significantly with the leaf area and its ratio increased, and the growth was inhibited obviously. The biomass aboveground was more than that underground. The ratios of leaf biomass and newly emerging branches biomass of first continuous cropping poplar seedling were relatively high. With the continuous cropping generations and growth cycle increasing, poplar seedling had a growth strategy to improve the ratio of root-shoot and root-leaf to adapt the limited soil nutrient of continuous cropping. PMID:25401150

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.

A diameter growth model for single-stem growth forms for the interior west forest inventory and analysis’s region

Treesearch

Michael T. Thompson

2015-01-01

The Interior West Forest Inventory and Analysis Unit (IWFIA) will soon transition from a regional system to a national FIA system for compiling estimates of forest growth, removals, and mortality. The national system requires regional diameter-growth models to estimate diameters on trees in situations where the initial or terminal diameter is not known at the beginning...

Antioxidants and anti-stress compounds improve the survival of cryopreserved Arabidopsis seedlings

USDA-ARS?s Scientific Manuscript database

Cryopreservation is a safe and cost-effective tool for the long-term storage of plant germplasm. Successful cryopreservation depends on suitable cryoprotection protocol. In Arabidopsis seedlings cryopreservation, the growth ability could be partly restored in 60-h seedlings, whereas 72-h seedlings d...

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...

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.

Management implications of using tree shelters for restoration of high elevation spruce-fir forests in the Rocky Mountains

Treesearch

Douglass F. Jacobs

2012-01-01

This paper presents a summary of a research project designed to study the use of tree shelters as a means to provide initial shade for planted Engelmann spruce (Picea englemannii Parry ex Engelm.) seedlings on a reforestation site in southwestern Colorado where several past planting attempts had failed. Study results following 2, 6, and 11 growing seasons were formally...

Rehabilitation of an oak planting project on cleared rangeland using treeshelters and grazing: a ten-year saga

Treesearch

Jerry Tecklin; Michael Connor; Douglas D. McCreary

2002-01-01

On a 2-hectare site at the Sierra Foothill Research and Extension Center near Marysville, California, 1,440 blue oaks (Quercus douglasii) were planted during 1990-91 in an attempt to re-vegetate an oak woodland that had been almost totally cleared for cattle grazing during the mid-1960s. This initial planting of acorns, 4-month old seedlings, and 1-...

Parasite Removal, but Not Herbivory, Deters Future Parasite Attachment on Tomato

PubMed Central

Tjiurutue, Muvari Connie; Palmer-Young, Evan C.; Adler, Lynn S.

2016-01-01

Plants face many antagonistic interactions that occur sequentially. Often, plants employ defense strategies in response to the initial damage that are highly specific and can affect interactions with subsequent antagonists. In addition to herbivores and pathogens, plants face attacks by parasitic plants, but we know little about how prior herbivory compared to prior parasite attachment affects subsequent host interactions. If host plants can respond adaptively to these different damage types, we predict that prior parasitism would have a greater deterrent effect on subsequent parasites than would prior herbivory. To test the effects of prior parasitism and prior herbivory on subsequent parasitic dodder (Cuscuta spp.) preference, we conducted two separate greenhouse studies with tomato hosts (Solanum lycopersicum). In the first experiment, we tested the effects of previous dodder attachment on subsequent dodder preference on tomato hosts using three treatments: control plants that had no previous dodder attachment; dodder-removed plants that had an initial dodder seedling attached, removed and left in the same pot to simulate parasite death; and dodder-continuous plants with an initial dodder seedling that remained attached. In the second experiment, we tested the effects of previous caterpillar damage (Spodoptera exigua) and mechanical damage on future dodder attachment on tomato hosts. Dodder attached most slowly to tomato hosts that had dodder plants previously attached and then removed, compared to control plants or plants with continuous dodder attachment. In contrast, herbivory did not affect subsequent dodder attachment rate. These results indicate that dodder preference depended on the identity and the outcome of the initial attack, suggesting that early-season interactions have the potential for profound impacts on subsequent community dynamics. PMID:27529694

Source-sink regulation of cotyledonary reserve mobilization during cashew (Anacardium occidentale) seedling establishment under NaCl salinity.

PubMed

Voigt, Eduardo Luiz; Almeida, Tânia Dias; Chagas, Roberta Magalhães; Ponte, Luiz Ferreira Aguiar; Viégas, Ricardo Almeida; Silveira, Joaquim Albenísio Gomes

2009-01-01

Seedling establishment is a critical process to crop productivity, especially under saline conditions. This work was carried out to investigate the hypothesis that reserve mobilization is coordinated with salt-induced inhibition of seedling growth due to changes in source-sink relations. To test this hypothesis, cashew nuts (Anacardium occidentale) were sown in vermiculite irrigated daily with distilled water (control) or 50mM NaCl and they were evaluated at discrete developmental stages from the seed germination until the whole seedling establishment. The salt treatment coordinately delayed the seedling growth and the cotyledonary reserve mobilization. However, these effects were more pronounced at late seedling establishment than in earlier stages. The storage protein mobilization was affected by salt stress before the lipid and starch breakdown. The globulin fraction represented the most important storage proteins of cashew cotyledons, and its mobilization was markedly delayed by NaCl along the seedling establishment. Free amino acids were mostly retained in the cotyledons of salt-treated seedlings when the mobilization of storage proteins, lipids and starch was strongly delayed. Proline was not considerably accumulated in the cotyledons of cashew seedlings as a response to NaCl salinity. According to these results it is noteworthy that the salt-induced inhibition of seedling growth is narrowly coordinated with the delay of reserve mobilization and the accumulation of hydrolysis products in cotyledons. Also, it was evidenced that free amino acids, especially those related to nitrogen transport, are potential signals involved in the regulation of storage protein hydrolysis during cashew seedling establishment under NaCl salinity.

Component optimization of dairy manure vermicompost, straw, and peat in seedling compressed substrates using simplex-centroid design.

PubMed

Yang, Longyuan; Cao, Hongliang; Yuan, Qiaoxia; Luoa, Shuai; Liu, Zhigang

2018-03-01

Vermicomposting is a promising method to disposal dairy manures, and the dairy manure vermicompost (DMV) to replace expensive peat is of high value in the application of seedling compressed substrates. In this research, three main components: DMV, straw, and peat, are conducted in the compressed substrates, and the effect of individual components and the corresponding optimal ratio for the seedling production are significant. To address these issues, the simplex-centroid experimental mixture design is employed, and the cucumber seedling experiment is conducted to evaluate the compressed substrates. Results demonstrated that the mechanical strength and physicochemical properties of compressed substrates for cucumber seedling can be well satisfied with suitable mixture ratio of the components. Moreover, DMV, straw, and peat) could be determined at 0.5917:0.1608:0.2475 when the weight coefficients of the three parameters (shoot length, root dry weight, and aboveground dry weight) were 1:1:1. For different purpose, the optimum ratio can be little changed on the basis of different weight coefficients. Compressed substrate is lump and has certain mechanical strength, produced by application of mechanical pressure to the seedling substrates. It will not harm seedlings when bedding out the seedlings, since the compressed substrate and seedling are bedded out together. However, there is no one using the vermicompost and agricultural waste components of compressed substrate for vegetable seedling production before. Thus, it is important to understand the effect of individual components to seedling production, and to determine the optimal ratio of components.

Interannual variation in rainfall, drought stress and seedling mortality may mediate monodominance in tropical flooded forests.

PubMed

Lopez, Omar R; Kursar, Thomas A

2007-11-01

Flood tolerance is commonly regarded as the main factor explaining low diversity and monodominance in tropical swamps. In this study we examined seedling mortality in relation to seasonality, i.e., flooding versus drought, of the dominant tree species (Prioria copaifera), and three associated species (Pterocarpus officinalis, Carapa guianensis and Pentaclethra macroloba), in seasonally flooded forests (SFF) in Darien, Panama. Seedling mortality differed among species, years and seasons. Prioria seedlings experienced the lowest overall mortality, and after 3 years many more Prioria seedlings remained alive than those of any of the associated species. In general, within species, larger seedlings had greater survival. Seed size, which can vary by close to 2 orders of magnitude in Prioria, had a confounding effect with that of topography. Large-seeded Prioria seedlings experienced 1.5 times greater mortality than small-seeded seedlings, as large-seeded Prioria seedlings were more likely to be located in depressions. This finding suggests that seed size, plant size and topography are important in understanding SFF regeneration. For all species, seedling mortality was consistently greater during the dry season than during flooding. For Prioria, dry season seedling mortality was correlated with drought stress, that is, high mortality during the long El Niño dry season of 1998 and the normal dry season of 2000, but very low dry season mortality during the mild dry season of 1999. Prioria's ability to dominate in seasonally flooded forest of Central America is partly explained by its low drought-related mortality in comparison to associated species.

Species-Specific Effects of Woody Litter on Seedling Emergence and Growth of Herbaceous Plants

PubMed Central

Koorem, Kadri; Price, Jodi N.; Moora, Mari

2011-01-01

The effect of litter on seedling establishment can influence species richness in plant communities. The effect of litter depends on amount, and also on litter type, but relatively little is known about the species-specific effects of litter. We conducted a factorial greenhouse experiment to examine the effect of litter type, using two woody species that commonly co-occur in boreonemoral forest—evergreen spruce (Picea abies), deciduous hazel (Corylus avellana), and a mixture of the two species—and litter amount—shallow (4 mm), deep (12 mm) and leachate—on seedling emergence and biomass of three understorey species. The effect of litter amount on seedling emergence was highly dependent on litter type; while spruce needle litter had a significant negative effect that increased with depth, seedling emergence in the presence of hazel broadleaf litter did not differ from control pots containing no litter. Mixed litter of both species also had a negative effect on seedling emergence that was intermediate compared to the single-species treatments. Spruce litter had a marginally positive (shallow) or neutral effect (deep) on seedling biomass, while hazel and mixed litter treatments had significant positive effects on biomass that increased with depth. We found non-additive effects of litter mixtures on seedling biomass indicating that high quality hazel litter can reduce the negative effects of spruce. Hazel litter does not inhibit seedling emergence; it increases seedling growth, and creates better conditions for seedling growth in mixtures by reducing the suppressive effect of spruce litter, having a positive effect on understorey species richness. PMID:22028890

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...

Implications of large oak seedlings on problematic deer herbivory

Treesearch

Christopher M. Oswalt; Wayne K. Clatterbuck; Allan E. Houston; Scott E. Schlarbaum

2006-01-01

Seedling herbivory by whitetail deer [Odocoileus virginianus (Boddaert)] can be a significant problem where artificial regeneration is attempted. We examined the relationship between deer herbivory and morphological traits of northern red oak (Quercus rubra L.) seedlings for two growing seasons for both browsed and non-browsed seedlings. Logistic...

Interim Guidelines for Growing Longleaf Seedlings in Containers

Treesearch

James P. Barnett; Mark J. Hainds; George A. Hernandez

2002-01-01

The demand for container longleaf pine (Pinus palustris Mill.) planting stock continues to increase each year. A problem facing both producers and users of container seedlings is the lack of target seedling specifications. Outplanting and evaluating performance of seedlings with a range of physiological and morphological characteristics, over a...

Grazing on Regeneration Sites Encourages Pine Seedling Growth

Treesearch

Raymond D. Ratliff; Renee G. Denton

1995-01-01

Effects of season-long, deferred-rotation, and rest-rotation grazing, on ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedling growth and herbaceous vegetation control were studied in regeneration sites at Boyd Hill, Modoc National Forest, California. Seedlings were planted in 1989. Pine seedling survival and damage did not differ, but the...

Fertilization Tests With Potted Red Oak Seedlings

Treesearch

Robert E. Phares

1971-01-01

Soil-pot tests with red oak seedlings indicated that forest soils supplied more N and P and produced better seedling growth than old-field soils. Growth was closely correlated with content of N and P in the foliage. K fertilization did not improve seedling growth on any of the soils studied.

Seedling root targets

Treesearch

Diane L. Haase

2011-01-01

Roots are critical to seedling performance after outplanting. Although root quality is not as quick and simple to measure as shoot quality, target root characteristics should be included in any seedling quality assessment program. This paper provides a brief review of root characteristics most commonly targeted for operational seedling production. These are: root mass...

Longleaf Seedling Trends

Treesearch

Mark J. Hainds

2002-01-01

Demand for longleaf pine (Pinus palustris Mill.) seedlings continues to increase throughout the Southeast. Overall production of longleaf pine seedlings has increased annually for at least the last 3 years (51 percent increase over the past 3 years), while demand for seedlings has continued to exceed the supply. There are several reasons for the...

Tolerance of loblolly pine seedlings to glyphosate

Treesearch

James D. Haywood; Thomas W. Melder

1990-01-01

Broadcasting glyphosate herbicide over loblolly pine (Pinus taeda L.) may provide enough early-season weed control to allow seedlings to establish themselves more rapidly, but glyphosate can, injure young trees. To examine the question of seedling injury, four rates of glyphosate were broadcast evenly over planted loblolly pine seedlings, competing...

An Appraisal of the Occurrence of the More Serious Tree Pests and Infectious Diseases in Poland in 1980 and a Forecast of Their Appearance in 1981,

DTIC Science & Technology

1982-10-28

122 2. Verticillium deciduous tree wilt (Verticillium alboatrum) ...... 124 3. Gray mold rot of conifer seedlings ( Botrytis cinerea ...or Botrytis cinerea . The overall occurrence of seedling wilt disease in young forest tree nur- series is shown in Table 53. Parasitic seedling wilt...successive years. 3. Gray mold rot of conifer seedlings ( Botrytis cinerea ) The occurrence of conifer seedling gray mold rot was confirmed on black pine

Environment sensing in spring-dispersed seeds of a winter annual Arabidopsis influences the regulation of dormancy to align germination potential with seasonal changes

PubMed Central

Footitt, Steven; Clay, Heather A; Dent, Katherine; Finch-Savage, William E

2014-01-01

Seed dormancy cycling plays a crucial role in the lifecycle timing of many plants. Little is known of how the seeds respond to the soil seed bank environment following dispersal in spring into the short-term seed bank before seedling emergence in autumn.Seeds of the winter annual Arabidopsis ecotype Cvi were buried in field soils in spring and recovered monthly until autumn and their molecular eco-physiological responses were recorded.DOG1 expression is initially low and then increases as dormancy increases. MFT expression is negatively correlated with germination potential. Abscisic acid (ABA) and gibberellin (GA) signalling responds rapidly following burial and adjusts to the seasonal change in soil temperature. Collectively these changes align germination potential with the optimum climate space for seedling emergence.Seeds naturally dispersed to the soil in spring enter a shallow dormancy cycle dominated by spatial sensing that adjusts germination potential to the maximum when soil environment is most favourable for germination and seedling emergence upon soil disturbance. This behaviour differs subtly from that of seeds overwintered in the soil seed bank to spread the period of potential germination in the seed population (existing seed bank and newly dispersed). As soil temperature declines in autumn, deep dormancy is re-imposed as seeds become part of the persistent seed bank. PMID:24444091

Reduced translocation of current photosynthate precedes changes in gas exchange for Quercus rubra seedlings under flooding stress.

PubMed

Sloan, Joshua L; Islam, M Anisul; Jacobs, Douglass F

2016-01-01

Northern red oak (Quercus rubra L.) seedlings are frequently planted on suboptimal sites in their native range in North America, subjecting them to environmental stresses, such as flooding, for which they may not be well adapted. Members of the genus Quercus exhibit a wide range of responses to flooding, and responses of northern red oak to flooding remain inadequately described. To better understand the physiological effects of root system inundation in post-transplant northern red oak seedlings and the effects of flooding on endogenous patterns of resource allocation within the plant, we observed the effects of short-term flooding initiated at the linear shoot growth stage on net photosynthetic rates, dark respiration, chlorophyll fluorescence (Fv/Fm) and translocation of (13)C-labeled current photosynthate. Downward translocation of current photosynthate declined after 4 days of flooding and was the first measured physiological response to flooding; net photosynthetic rates decreased and dark respiration rates increased after 7 days of flooding. Short-term flooding did not affect maximal potential efficiency of photosystem II (Fv/Fm). The finding that decreased downward translocation of (13)C-labeled current photosynthate preceded reduced net photosynthesis and increased dark respiration during flooding suggests the occurrence of sink-limited photosynthesis under these conditions. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Expression profiling of selected glutathione transferase genes in Zea mays (L.) seedlings infested with cereal aphids.

PubMed

Sytykiewicz, Hubert; Chrzanowski, Grzegorz; Czerniewicz, Paweł; Sprawka, Iwona; Łukasik, Iwona; Goławska, Sylwia; Sempruch, Cezary

2014-01-01

The purpose of this report was to evaluate the expression patterns of selected glutathione transferase genes (gst1, gst18, gst23 and gst24) in the tissues of two maize (Zea mays L.) varieties (relatively resistant Ambrozja and susceptible Tasty Sweet) that were colonized with oligophagous bird cherry-oat aphid (Rhopalosiphum padi L.) or monophagous grain aphid (Sitobion avenae L.). Simultaneously, insect-triggered generation of superoxide anion radicals (O2•-) in infested Z. mays plants was monitored. Quantified parameters were measured at 1, 2, 4, 8, 24, 48 and 72 h post-initial aphid infestation (hpi) in relation to the non-infested control seedlings. Significant increases in gst transcript amounts were recorded in aphid-stressed plants in comparison to the control seedlings. Maximal enhancement in the expression of the gst genes in aphid-attacked maize plants was found at 8 hpi (gst23) or 24 hpi (gst1, gst18 and gst24) compared to the control. Investigated Z. mays cultivars formed excessive superoxide anion radicals in response to insect treatments, and the highest overproduction of O2•- was noted 4 or 8 h after infestation, depending on the aphid treatment and maize genotype. Importantly, the Ambrozja variety could be characterized as having more profound increments in the levels of gst transcript abundance and O2•- generation in comparison with the Tasty Sweet genotype.

Pyrolysis of Large Black Liquor Droplets

NASA Technical Reports Server (NTRS)

Bartkus, Tadas P.; Dietrich, Daniel L.; T'ien, James S.; Wessel, Richard A.

2007-01-01

This paper presents the results of experiments involving the pyrolysis of large black liquor droplets in the NASA KC-135 reduced gravity aircraft. The reduced gravity environment facilitated the study of droplets up to 9 mm in diameter extending the results of previous studies to droplet sizes that are similar to those encountered in recovery boilers. Single black liquor droplets were rapidly inserted into a 923 K oven. The primary independent variables were the initial droplet diameter (0.5 mm to 9 mm), the black liquor solids content (66.12% - 72.9% by mass), and the ambient oxygen mole fraction (0.0 - 0.21). Video records of the experiments provided size and shape of the droplets as a function of time. The results show that the particle diameter at the end of the drying stage (D(sub DRY)) increases linearly with the initial particle diameter (D(sub O)). The results further show that the ratio of the maximum swollen diameter (D(sub MAX)) to D(sub O) decreases with increasing D(sub O) for droplets with D(sub O) less than 4 mm. This ratio was independent of D(sub O) for droplets with D(sub O) greater than 4 mm. The particle is most spherical at the end of drying, and least spherical at maximum swollen size, regardless of initial sphericity and droplet size.

Pyrolysis of Large Black Liquor Droplets

NASA Technical Reports Server (NTRS)

Bartkus, Tadas P.; T'ien, James S.; Dietrich, Daniel L.; Wessel, Richard A.

2007-01-01

This paper presents the results of experiments involving the pyrolysis of large black liquor droplets in the NASA KC-135 reduced gravity aircraft. The reduced gravity environment facilitated the study of droplets up to 9 mm in diameter extending the results of previous studies to droplet sizes that are similar to those encountered in recovery boilers. Single black liquor droplets were rapidly inserted into a 923 K oven. The primary independent variables were the initial droplet diameter (0.5 mm to 9 mm), the black liquor solids content (66.12% - 72.9% by mass), and the ambient oxygen mole fraction (0.0 - 0.21). Video records of the experiments provided size and shape of the droplets as a function of time. The results show that the particle diameter at the end of the drying stage (D(sub DRY) ) increases linearly with the initial particle diameter (D(sub O)). The results further show that the ratio of the maximum swollen diameter (D(sub MAX)) to D(sub O) decreases with increasing D(sub O) for droplets with D(sub O) less than 4 mm. This ratio was independent of D(sub O) for droplets with D(sub O) greater than 4 mm. The particle is most spherical at the end of drying, and least spherical at maximum swollen size, regardless of initial sphericity and droplet size.

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...

Facilitation and interference of seedling establishment by a native legume before and after wildfire

Treesearch

Erin Goergen; Jeanne C. Chambers

2011-01-01

In semi-arid ecosystems, heterogeneous resources can lead to variable seedling recruitment. Existing vegetation can influence seedling establishment by modifying the resource and physical environment. We asked how a native legume, Lupinus argenteus, modifies microenvironments in unburned and burned sagebrush steppe, and if L. argenteus presence facilitates seedling...

Foliar mineral content of forest and nursery-grown Douglas-fir seedlings.

Treesearch

Kenneth W. Krueger

1967-01-01

High-vigor seedlings are required for consistently successful reforestation, and mineral nutrition undoubtedly plays a large role in determining seedling vigor. Though no serious mineral deficiencies were known to exist in Northwest forest nurseries, assurance of adequate seedling nutrition would eliminate this factor as a possible cause of plantation failures....

Lime-amended growing medium causes seedling growth distortions

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R. Kasten Dumroese; Gale Thompson; David L. Wenny

1990-01-01

Although a commercial growing medium with incorporated agricultural lime had been successfully used for years, it caused growth distortion of coniferous and deciduous seedlings during 1988. Seedlings grown in the amended medium were stunted and chlorotic, often with disfigured needles and multiple tops. Seedlings grown in the same medium without incorporated lime grew...

Growing Longleaf Pine Seedlings in Containers

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James P. Barnett; John M. McGilvray

2000-01-01

We provide basic guidelines for nursery production of longleaf pine ( Pinus palustris P. Mill. [Pinaceae]) seedlings in containers. The best seedlings are spring sown, grown outdoors in full sun in cavities with a 100-ml (6 in3) volume, 11-cm (4.5 in) depth, and a density around 535 seedlings per m2 (...

Ostryopsis davidiana seedlings inoculated with ectomycorrhizal fungi facilitate formation of mycorrhizae on Pinus tabulaeformis seedlings

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Shu-Lan Bai; Guo-Lei Li; Yong Liu; R. Kasten Dumroese; Rui-Heng Lv

2009-01-01

Reforestation in China is important for reversing anthropogenic activities that degrade the environment. Pinus tabulaeformis is desired for these activities, but survival and growth of seedlings can be hampered by lack of ectomycorrhizae. When outplanted in association with Ostryopsis davidiana plants on reforestation sites, P. tabulaeformis seedlings become...