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Sample records for nothofagus dombeyi seedlings

  1. Thermal energy dissipation and its components in two developmental stages of a shade-tolerant species, Nothofagus nitida, and a shade-intolerant species, Nothofagus dombeyi.

    PubMed

    Reyes-Díaz, Marjorie; Ivanov, Alexander G; Huner, Norman P A; Alberdi, Miren; Corcuera, Luis J; Bravo, León A

    2009-05-01

    Nothofagus dombeyi (Mirb.) Blume and Nothofagus nitida (Phil.) Krasser, two evergreens in the South Chilean forest, regenerate in open habitats and under the canopy, respectively. Both overtop the forest canopy when they are in the adult stage, suggesting that their photoprotective mechanisms differ in ontogenetic dynamics. We postulated that N. nitida, a shade-tolerant species increases its capacity to tolerate photoinhibitory conditions (low temperature and high irradiance) by thermal energy dissipation of excess energy during its transition from the seedling to the adult stage, whereas N. dombeyi, a shade-intolerant species, maintains a high capacity for photoprotection by thermal energy dissipation from the seedling to the adult stage. To test this hypothesis, the main photoprotective mechanisms in plants - the fast- and slow-relaxing components of thermal energy dissipation (NPQ, non-photochemical quenching) NPQ(F) and NPQ(S), respectively, and state transitions - were studied in seedlings and adults of both species grown in their natural habitats and in a common garden. In adults, NPQ(F) and NPQ(S) did not differ between species and seasons. The greatest differences in these parameters were observed in seedlings. The xanthophyll cycle was more active in N. dombeyi seedlings than in N. nitida seedlings at low temperature and high irradiance, consistent with a higher NPQ(F) in N. dombeyi. Under all study conditions, N. nitida seedlings had higher NPQ(S) than N. dombeyi seedlings. The state transition capability was higher in N. nitida seedlings than in N. dombeyi seedlings. Therefore, although (shade-intolerant) N. dombeyi was able to thermally dissipate the excess absorbed energy, under natural conditions its photochemical energy quenching was efficient in both developmental stages, decreasing its need for thermal dissipation. In contrast, the seedlings of N. nitida were more sensitive to photoinhibition than the adult trees, suggesting a change from shade

  2. Effect of ectomycorrhizal colonization and drought on reactive oxygen species metabolism of Nothofagus dombeyi roots.

    PubMed

    Alvarez, Maricel; Huygens, Dries; Fernandez, Carlos; Gacitúa, Yessy; Olivares, Erick; Saavedra, Isabel; Alberdi, Miren; Valenzuela, Eduardo

    2009-08-01

    Infection with ectomycorrhizal fungi can increase the ability of plants to resist drought stress through morphophysiological and biochemical mechanisms. However, the metabolism of antioxidative enzyme activities in the ectomycorrhizal symbiosis remains poorly understood. This study investigated biomass production, reactive oxygen metabolism (hydrogen peroxide and malondialdehyde concentration) and antioxidant enzyme activity (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase) in pure cultures of the ectomycorrhizal fungi Descolea antartica Sing. and Pisolithus tinctorius (Pers.) Coker & Couch, and non-mycorrhizal and mycorrhizal roots of Nothofagus dombeyi (Mirb.) roots under well-watered conditions and drought conditions (DC). The studied ectomycorrhizal fungi regulated their antioxidative enzyme metabolism differentially in response to drought, resulting in cellular damage in D. antartica but not in P. tinctorius. Ectomycorrhizal inoculation and water treatment had a significant effect on all parameters studied, including relative water content of the plant. As such, N. dombeyi plants in symbiosis experienced a lower oxidative stress effect than non-mycorrhizal plants under DC. Additionally, ectomycorrhizal N. dombeyi roots showed a greater antioxidant enzyme activity relative to non-mycorrhizal roots, an effect which was further expressed under DC. The association between the non-specific P. tinctorius and N. dombeyi had a more effective reactive oxygen species (ROS) metabolism than the specific D. antartica-N. dombeyi symbiosis. We conclude that the combination of effective ROS prevention and ROS detoxification by ectomycorrhizal plants resulted in reduced cellular damage and increased plant growth relative to non-mycorrhizal plants under drought. PMID:19483186

  3. Ectomycorrhizal fungi enhance nitrogen and phosphorus nutrition of Nothofagus dombeyi under drought conditions by regulating assimilative enzyme activities.

    PubMed

    Alvarez, Maricel; Huygens, Dries; Olivares, Erick; Saavedra, Isabel; Alberdi, Miren; Valenzuela, Eduardo

    2009-08-01

    Drought stress conditions (DC) reduce plant growth and nutrition, restraining the sustainable reestablishment of Nothofagus dombeyi in temperate south Chilean forest ecosystems. Ectomycorrhizal symbioses have been documented to enhance plant nitrogen (N) and phosphorus (P) uptake under drought, but the regulation of involved assimilative enzymes remains unclear. We studied 1-year-old N. dombeyi (Mirb.) Oerst. plants in association with the ectomycorrhizal fungi Pisolithus tinctorius (Pers.) Coker & Couch. and Descolea antartica Sing. In greenhouse experiments, shoot and root dry weights, mycorrhizal colonization, foliar N and P concentrations, and root enzyme activities [glutamate synthase (glutamine oxoglutarate aminotransferase (GOGAT), EC 1.4.1.13-14), glutamine synthetase (GS, EC 6.3.1.2), glutamate dehydrogenase (GDH, EC 1.4.1.2-4), nitrate reductase (NR, EC 1.6.6.1), and acid phosphomonoesterase (PME, EC 3.1.3.1-2)] were determined as a function of soil-water content. Inoculation of N. dombeyi with P. tinctorius and D. antartica significantly stimulated plant growth and increased plant foliar N and P concentrations, especially under DC. Ectomycorrhizal inoculation increased the activity of all studied enzymes relative to non-mycorrhizal plants under drought. We speculate that GDH is a key enzyme involved in the enhancement of ectomycorrhizal carbon (C) availability by fuelling the tricarboxylic acid (TCA) cycle under conditions of drought-induced carbon deficit. All studied assimilative enzymes of the ectomycorrhizal associations, involved in C, N, and P transfers, are closely interlinked and interdependent. The up-regulation of assimilative enzyme activities by ectomycorrhizal fungal root colonizers acts as a functional mechanism to increase seedling endurance to drought. We insist upon incorporating ectomycorrhizal inoculation in existing Chilean afforestation programs. PMID:19470091

  4. Using Genome-Wide SNP Discovery and Genotyping to Reveal the Main Source of Population Differentiation in Nothofagus dombeyi (Mirb.) Oerst. in Chile

    PubMed Central

    González, Jorge; Fuentes, Glenda; Alarcón, Diego; Ruiz, Eduardo

    2016-01-01

    Within a woody plant species, environmental heterogeneity has the potential to influence the distribution of genetic variation among populations through several evolutionary processes. In some species, a relationship between environmental characteristics and the distribution of genotypes can be detected, showing the importance of natural selection as the main source of differentiation. Nothofagus dombeyi (Mirb.) Oerst. (Nothofagaceae) is an endemic tree species occurring both in Chile and in Argentina temperate forests. Postglacial history has been studied with chloroplast DNA and evolutionary forces shaping genetic variation patterns have been analysed with isozymes but fine-scale genetic diversity studies are needed. The study of demographic and selection histories in Nothofagus dombeyi requires more informative markers such as single nucleotide polymorphisms (SNP). Genotyping-by-Sequencing tools now allow studying thousands of SNP markers at reasonable prices in nonmodel species. We investigated more than 10 K SNP loci for signatures of local adaptation and showed that interrogation of genomic resources can identify shifts in genetic diversity and putative adaptive signals in this nonmodel woody species. PMID:27446942

  5. Using Genome-Wide SNP Discovery and Genotyping to Reveal the Main Source of Population Differentiation in Nothofagus dombeyi (Mirb.) Oerst. in Chile.

    PubMed

    Hasbún, Rodrigo; González, Jorge; Iturra, Carolina; Fuentes, Glenda; Alarcón, Diego; Ruiz, Eduardo

    2016-01-01

    Within a woody plant species, environmental heterogeneity has the potential to influence the distribution of genetic variation among populations through several evolutionary processes. In some species, a relationship between environmental characteristics and the distribution of genotypes can be detected, showing the importance of natural selection as the main source of differentiation. Nothofagus dombeyi (Mirb.) Oerst. (Nothofagaceae) is an endemic tree species occurring both in Chile and in Argentina temperate forests. Postglacial history has been studied with chloroplast DNA and evolutionary forces shaping genetic variation patterns have been analysed with isozymes but fine-scale genetic diversity studies are needed. The study of demographic and selection histories in Nothofagus dombeyi requires more informative markers such as single nucleotide polymorphisms (SNP). Genotyping-by-Sequencing tools now allow studying thousands of SNP markers at reasonable prices in nonmodel species. We investigated more than 10 K SNP loci for signatures of local adaptation and showed that interrogation of genomic resources can identify shifts in genetic diversity and putative adaptive signals in this nonmodel woody species. PMID:27446942

  6. Ectomycorrhizas naturally established in Nothofagus nervosa seedlings under different cultivation practices in a forest nursery.

    PubMed

    Fernández, Natalia V; Marchelli, Paula; Fontenla, Sonia B

    2013-10-01

    Mycorrhizas are mutualistic associations between soil fungi and plant roots which usually improve water and nutrient uptake, influencing plant fitness. Nothofagus nervosa (Raulí) is an ecologically and economically important species of South American temperate forests. Since this native tree species yields valuable timber, it was overexploited and its natural distribution area was critically reduced, so it is currently included in domestication and conservation programs. Among the factors that should be considered in these programs are the ectomycorrhizas (EcM), which would be important for the successful establishment and survival of outplanted seedlings. The aim of this work was to analyze the abundance and diversity of EcM in N. nervosa nursery-cultivated seedlings assessed by morphotyping, fungal isolation, and DNA sequencing. Arbuscular mycorrhiza (AM) occurrence was also studied. A 2-year trial was conducted following the cultivation conditions used for domestication programs. Seedlings were cultivated under two different cultivation practices (greenhouse and nursery soil) without artificial inoculation of mycorrhizal fungi. Seedlings' roots were examined at different times. It was observed that they developed EcM between 6 and 12 months after germination and AMs were not detected in any plant. The most abundant ectomycorrhizal fungi present in seedlings' roots were Tomentella ellisii (Basidiomycota) and an unidentified fungus named Ascomicetous EcM sp. 1. Abundance and diversity of EcM varied between the two cultivation techniques analyzed in this study, since seedlings that continued growing in the greenhouse had higher colonization values, but those transplanted to the nursery soil were colonized by a higher diversity of fungal taxa. PMID:23636582

  7. Foliar anatomical and morphological variation in Nothofagus pumilio seedlings under controlled irradiance and soil moisture levels.

    PubMed

    Ivancich, Horacio S; Lencinas, María V; Pastur, Guillermo J Martínez; Esteban, Rosina M Soler; Hernández, Luis; Lindstrom, Ivone

    2012-05-01

    Foliar anatomy and morphology are strongly related to physiological performance; therefore, phenotypic plasticity in leaves to variations in environmental conditions, such as irradiance and soil moisture availability, can be related to growth rate and survivorship, mainly during critical growth phases, such as establishment. The aim of this work was to analyze changes in the foliar internal anatomy (tissue proportions and cell dimensions) and external morphology (leaf length, width and area) of Nothofagus pumilio (Poepp. et Endl.) Krasser seedlings growing in a greenhouse under controlled irradiance (three levels) and soil moisture (two levels) during one growing season (measured three times), and to relate them to physiological traits. Three irradiance levels (4, 26 and 64% of the natural incident light) and two soil moisture levels (40 and 80% soil capacity) were evaluated during November, January and March. Internal foliar anatomy of seedlings was analyzed using digital photographs of histological cuttings, while leaf gross morphology was measured using digital calipers and image analysis software. Most internal anatomical variables presented significant differences under different irradiance levels during the growing season, but differences were not detected between soil moisture levels. Palisade parenchyma was the tissue most sensitive to irradiance levels, and high irradiance levels (64% natural incident light) produced greater values in most of the internal anatomical variables than lower irradiance levels (4-24% natural incident light). Complementarily, larger leaves were observed in medium and low irradiance levels, as well as under low soil moisture levels (40% soil capacity). The relationship of main results with some eco-physiological traits was discussed. Foliar internal anatomical and external morphological plasticity allows quick acclimation of seedlings to environmental changes (e.g., during harvesting). These results can be used to propose new

  8. Selection of Nothofagus host trees by the aphids Neuquenaphis staryi and Neuquenaphis edwardsi.

    PubMed

    Russell, Graeme B; Faundez, Eric H; Niemeyer, Hermann M

    2004-11-01

    Leaf volatiles were collected from three Nothofagus species growing in close proximity in Los Ruiles National Reserve, Chile. The volatile preparation from leaves of No. alessandrii were attractive to the specialist aphid, Neuquenaphis staryi, but not to the generalist aphid, Ne. edwardsi, while the volatile preparations of No. dombeyi and No. glauca were attractive to Ne. edwardsi, but not to Ne. staryi. This reflects the pattern of aphid/host-plant associations. Alpha-Agarofuran was found to occur in all leaf volatile preparations and was shown by electroantennography and olfactometry to be attractive for both Neuquenaphis spp., suggesting it may be the Nothofagus host-recognition factor for Neuquenaphis. The factor(s) mediating Ne. stayi's specialization on No. alessandrii remain to be identified. PMID:15672667

  9. Physiological responses to water stress and waterlogging in Nothofagus species.

    PubMed

    Sun, O J; Sweet, G B; Whitehead, D; Buchan, G D

    1995-10-01

    Gas exchange and water relations were investigated in Nothofagus solandri var. cliffortioides (Hook. f.) Poole (mountain beech) and Nothofagus menziesii (Hook. f.) Oerst (silver beech) seedlings in response to water stress and waterlogging. At soil matric potentials (Psi(soil)) above -0.005 MPa, N. solandri had significantly higher photosynthetic rates (A), and stomatal and residual conductances (g(sw) and g(rc)), and lower predawn xylem water potentials (Psi(predawn)) than N. menziesii. The relative tolerance of plants to water stress was defined in terms of critical soil matric potential (Psi(cri)) and lethal xylem water potential (Psi(lethal)). The estimated values of Psi(cri) and Psi(lethal) were -1.2 and -7 MPa, respectively, for N. solandri, and -0.7 and -4 MPa, respectively, for N. menziesii. Photosynthesis was sustained to a xylem water potential (Psi(xylem)) of -7 MPa in N. solandri compared with -4 MPa in N. menziesii. Following rewatering, both A and Psi(xylem) recovered quickly in N. solandri, whereas the two variables recovered more slowly in N. menziesii. During the development of water stress, nonstomatal inhibition significantly affected A in both N. solandri and N. menziesii. Nothofagus menziesii was more susceptible to inhibition of A by waterlogging than N. solandri. However, the tolerance of N. solandri to severe waterlogging was also limited as a result of a failure to form adventitious roots, suggesting a lack of adaptation to these conditions. The differences in tolerance to water stress and waterlogging between the two species are consistent with the distribution patterns of N. solandri and N. menziesii in New Zealand. PMID:14965996

  10. Retracing the evolutionary history of Nothofagus in its geo-climatic context: new developments in the emerging field of phylogeology.

    PubMed

    Acosta, M C; Mathiasen, P; Premoli, A C

    2014-11-01

    Phylogeographic studies have made a significant contribution to the interpretation of genetic lineage distribution in response to climate changes, such as during glaciation events of the Neogene. However, the effects of ancient landscapes associated with global sea level rises, tectonic processes, and climatology driving lineage evolution have been largely overlooked. These effects can be tested in widespread lineages of cold-tolerant species that have endured cooling, and thus, phylogeographic patterns may reflect large-scale processes that were not reset by the ice ages. We hereby combine geological evidence from marine sedimentary basins, Andean orogeny, and climatology with molecular dating and statistical phylogeography to infer how geological and climatic processes affected the distribution of lineages in cold-tolerant Nothofagus species during the Cenozoic. A total of 239 populations along the entire range of all species within the genus Nothofagus (N. antarctica, N. betuloides, N. dombeyi, N. nitida, and N. pumilio) were sampled and analyzed by sequencing three non-coding regions of the chloroplast. We found 30 chloroplast DNA haplotypes that were geographically structured. Molecular dating calibrated with fossils revealed that ancestral lineages appeared in Eocene/Oligocene, whereas most divergences took place during the Miocene; in turn, Bayesian skyline plots showed that population expansion occurred in the Early Pleistocene (1.5-1 million years ago). Lineage divergence from all wide-ranging Nothofagus was spatially and temporally concordant with episodic marine transgressions and warmer times in Patagonia during Eocene/Miocene Epochs. Long-lasting stable raised areas preserved haplotype diversity throughout Patagonia, from where cold-tolerant taxa expanded their ranges during pre-Quaternary times. The detailed study of such ancient divergences is novel and allows us to infer the effects of geological processes on distribution patterns of ancient

  11. Introduced species and management of a Nothofagus/Austrocedrus forest.

    PubMed

    Simberloff, Daniel; Relva, Maria Andrea; Nunez, Martin

    2003-02-01

    Isla Victoria (Nahuel Huapi National Park, Argentina), a large island dominated by native Nothofagus and Austrocedrus forest, has old plantations of many introduced tree species, some of which are famed invaders of native ecosystems elsewhere. There are also large populations of introduced deer and shrubs that may interact in a complex way with the introduced trees, as well as a recently arrived population of wild boar. Long-standing concern that the introduced trees will invade and transform native forest may be unwarranted, as there is little evidence of progressive invasion, even close to the plantations, despite over 50 years of opportunity. Introduced and native shrubs allow scattered introduced trees to achieve substantial size in abandoned pastures, but in almost all areas neither the trees nor the shrubs appear to be spreading beyond these sites. These shrub communities may be stable rather than successional, but the technology for restoring them to native forest is uncertain and probably currently impractical. Any attempt to remove the exotic tree seedlings and saplings from native forest would probably create the very conditions that would favor colonization by exotic plants rather than native trees, while simply clear-cutting the plantations would be unlikely to lead to regeneration of Nothofagus or Austrocedrus. The key to maintaining native forest is preventing catastrophic fire, as several introduced trees and shrubs would be favored over native dominant trees in recolonization. Deer undoubtedly interact with both native and introduced trees and shrubs, but their net effect on native forest is not yet clear, and specific management of deer beyond the current hunting by staff is unwarranted, at least if preventing tree invasion is the goal. The steep terrain and shallow soil make the recently arrived boar a grave threat to the native forest. Eradication is probably feasible and should be attempted quickly. PMID:12520381

  12. Relaxed molecular clock provides evidence for long-distance dispersal of Nothofagus (southern beech).

    PubMed

    Knapp, Michael; Stöckler, Karen; Havell, David; Delsuc, Frédéric; Sebastiani, Federico; Lockhart, Peter J

    2005-01-01

    Nothofagus (southern beech), with an 80-million-year-old fossil record, has become iconic as a plant genus whose ancient Gondwanan relationships reach back into the Cretaceous era. Closely associated with Wegener's theory of "Kontinentaldrift", Nothofagus has been regarded as the "key genus in plant biogeography". This paradigm has the New Zealand species as passengers on a Moa's Ark that rafted away from other landmasses following the breakup of Gondwana. An alternative explanation for the current transoceanic distribution of species seems almost inconceivable given that Nothofagus seeds are generally thought to be poorly suited for dispersal across large distances or oceans. Here we test the Moa's Ark hypothesis using relaxed molecular clock methods in the analysis of a 7.2-kb fragment of the chloroplast genome. Our analyses provide the first unequivocal molecular clock evidence that, whilst some Nothofagus transoceanic distributions are consistent with vicariance, trans-Tasman Sea distributions can only be explained by long-distance dispersal. Thus, our analyses support the interpretation of an absence of Lophozonia and Fuscospora pollen types in the New Zealand Cretaceous fossil record as evidence for Tertiary dispersals of Nothofagus to New Zealand. Our findings contradict those from recent cladistic analyses of biogeographic data that have concluded transoceanic Nothofagus distributions can only be explained by vicariance events and subsequent extinction. They indicate that the biogeographic history of Nothofagus is more complex than envisaged under opposing polarised views expressed in the ongoing controversy over the relevance of dispersal and vicariance for explaining plant biodiversity. They provide motivation and justification for developing more complex hypotheses that seek to explain the origins of Southern Hemisphere biota. PMID:15660155

  13. Declining moisture availability in late Eocene Antarctica as deduced from Nothofagus sporopollenin δ13C

    NASA Astrophysics Data System (ADS)

    Griener, K. W.; Nelson, D. M.; Warny, S.

    2012-12-01

    Palynological data demonstrate that significant changes in vegetation and climate occurred at the Eocene-Oligocene (E-O) Boundary on the Antarctic Peninsula. These changes include decreases in terrestrial palynomorph abundance and diversity as well as dinoflagellate assemblages that reflect colder sea surface temperatures and increased glaciation (Warny and Askin, 2011). Understanding the factors controlling these changes in climate and vegetation is a topic of great interest. One area of remaining uncertainty is how the hydrologic regime varied during Antarctica's shift from greenhouse to icehouse conditions. For example, estimates of Antarctic precipitation from around the E-O boundary based on plant leaf margins (e.g. Francis et al., 2008), clay mineralogy (e.g. Christian and Kennett, 1997), and models (Thorn and DeConto 2006) are vastly different. We used a moving-wire device interfaced with an isotope-ratio mass spectrometer (Sessions et al., 2005; Nelson et al., 2008) to analyze δ13C of small quantities of Nothofagus sporopollenin extracted from Antarctic Eocene SHALDRIL cores from ~35.9 Mya, just prior to the E-O Boundary (Bohaty et al., 2011). We also analyzed δ13C of modern Nothofagus sporopollenin from herbaria specimens and related these results to historical climate data. Our modern data show that carbon isotope discrimination (Δ) of Nothofagus sporopollenin is positively correlated with mean annual and growing-season precipitation, consistent with prior studies that demonstrate a strong relationship between Δ and water availability in C3 plants. Eocene Nothofagus Δ values progressively decreased through time, implying a decline in moisture availability. There is a close correlation between Nothofagus palynomorph abundance (Warny and Askin, 2011) and Δ, indicating that Nothofagus abundance declined in response to decreasing moisture availability. We consider changes in sea surface temperatures as well as increased glaciation as possible causes

  14. Effectiveness of fencing and hunting to control Lama guanicoe browsing damage: Implications for Nothofagus pumilio regeneration in harvested forests.

    PubMed

    Martínez Pastur, Guillermo; Soler, Rosina; Ivancich, Horacio; Lencinas, María V; Bahamonde, Héctor; Peri, Pablo L

    2016-03-01

    Browsing damage by native ungulates is often to be considered one of the reasons of regeneration failure in Nothofagus pumilio silvicultural systems. Fencing and hunting in forests at regeneration phase have been proposed to mitigate browsing effects. This study aims to determine effectiveness of these control methods in harvested forests, evaluating browsing damage over regeneration, as well as climate-related constraints (freezing or desiccation). Forest structure and regeneration plots were established in two exclosures against native ungulates (Lama guanicoe) by wire fences in the Chilean portion of Tierra del Fuego island, where tree regeneration density, growth, abiotic damage and quality (multi-stems and base/stem deformation) were assessed. Exclosures did not influence regeneration density (at the initial stage with < 1.3 m high, and at the advanced stage with >1.3 m high). However, sapling height at 10-years old was significantly lower outside (40-50 cm high) than inside exclosures (80-100 cm), and also increased their annual height growth, probably as a hunting effect. Likewise, quality was better inside exclosures. Alongside browsing, abiotic conditions negatively influenced sapling quality in the regeneration phase (20%-28% of all seedlings), but greatly to taller plants (as those from inside exclosure). This highlights the importance of considering climatic factors when analysing browsing effects. For best results, control of guanaco in recently harvested areas by fencing should be applied in combination with a reduction of guanaco density through continuous hunting. The benefits of mitigation actions (fencing and hunting) on regeneration growth may shorten the regeneration phase period in shelterwood cutting forests (30-50% less time), but incremental costs must be analysed in the framework of management planning by means of long-term studies. PMID:26708647

  15. Gymnopanella nothofagi, a new genus and species of gymnopoid fungi (Omphalotaceae) from Chilean Nothofagus forest.

    PubMed

    Sandoval-Leiva, Pablo Andrés; McDonald, Jennifer V; Thorn, R Greg

    2016-01-01

    A novel, lignicolous agaric from Nothofagus forests of southern Chile is described as a new genus and species, Gymnopanella nothofagi This taxon falls within the family Omphalotaceae as a sister group to Gymnopus in phylogenetic analyses based on sequences spanning the internal transcribed spacer region and D1/D2 region of nuclear 28S rDNA. Morphologically it is characterized by convex to flabellate basidiomata with distinctly gelatinized trama, pileipellis in the form of a cutis with erect fascicles of cylindrical, spirally incrusted hyphae and nonamyloid, broadly ellipsoid basidiospores. This combination of features, in particular the lack of a rameales structure, serve to distinguish Gymnopanella from Gymnopus, Marasmiellus and other similar genera of the Omphalotaceae or Marasmiaceae. The new taxon is known only from Chilean Nothofagus forests at approximately 45-46° south latitude, but concerted searching in similar habitats in surrounding areas or in New Zealand may extend the known range considerably. PMID:27055572

  16. Early Miocene Nothofagus in Antarctica based on fossil leaves from the Transantarctic Mountains

    NASA Astrophysics Data System (ADS)

    Wrobleski, S. A.; Ashworth, A. C.; Lewis, A. R.

    2014-12-01

    Nothofagus (Southern Beech) is the most widely reported plant from Cenozoic Antarctic fossil assemblages. Most of the fossils are of pollen morphotypes and it is assumed that the plants the pollen represents were growing on the continent. However, because of the uncertainties with systematics, long-distance dispersal, and reworking, it has been difficult to interpret the assemblages in terms of paleoenvironments and paleoclimate. Here, we report an in situ assemblage of Nothofagus leaves and pollen from the Friis Hills (77⁰ 45'S, 161⁰ 28'E). The leaves are preserved as carbonaceous impressions in brown, fissile shales that represent the deposits of a lake occupying a glacial valley. The leaves most probably accumulated from deciduous shrubs. Based on the stratigraphic relationship to a tephra with a 40 Ar/39 Ar age of c. 20 Ma, the leaf assemblage is of early Miocene age. Nothofagus pollen from the shale suggests that at least 3 species were represented. A total of 227 leaves were examined and lengths, widths, and areas recorded. The preservation is generally good but only a few of the specimens represent complete leaves; the spectrum is 30-100%. Plots of the measurements of the leaves provide a summary of size variation but were otherwise not useful for separating out different taxa . The most useful characters for establishing differences between the leaves were the leaf margins, of which three or four types were distinguished: 1. margins entire or finely serrate between ribs; 2. margins with one or two convex lobes between the ribs; 3. margins with convex lobes over the ribs. The leaf study indicates that three or possibly four species were co-inhabiting the valley in the early Miocene and were part of a dynamic vegetation that colonized the valley with each deglaciation. A possible analog today would be at low elevations in Tierra del Fuego where three species of Nothofagus coexist. The stem diameters of abundant wood preserved in adjacent facies indicates

  17. Halfway encounters: meeting points of colonization routes among the southern beeches Nothofagus pumilio and N. antarctica.

    PubMed

    Soliani, Carolina; Tsuda, Yoshiaki; Bagnoli, Francesca; Gallo, Leonardo A; Vendramin, Giovanni G; Marchelli, Paula

    2015-04-01

    The Patagonian region is characterized by a complex biogeographic history, with evidence of deep phylogeographic breaks shared among species. Of particular interest to conservation is the nature of colonization and settlement patterns after the last glacial period, including the detection of secondary contact between different lineages and/or hybridization among related species around phylogeographic breaks. Here we studied population demography and past hybridization of two widespread tree species endemic to South America, Nothofagus pumilio and N. antarctica. Using 8 nuclear microsatellites we genotyped 41 populations of both species. Genetic variation and structure across the geographic region were evaluated within and among species and the past demographic history of hybridization between the two species was inferred using Approximate Bayesian Computation (ABC). Northern and southern lineages were identified in each species, and Bayesian clustering revealed their convergence at mid latitudes (42°S). Spatial genetic structure (SGS) also indicated the existence of a genetic discontinuity at these latitudes, which is in agreement with previous data from maternal DNA markers. Several populations around 42-44°S presented high levels of genetic diversity with a decrease toward southern populations. Even though the species are clearly differentiated (G'ST=0.335), admixed gene pools were observed in both species. Two independent runs of ABC suggested that inter species admixture-like patterns occurred within the timescale of the Last Glacial Maximum (around 20,000 BP). We also provide evidences of recent and bi-directional hybridization/introgression between the two Nothofagus species and describe features of the populationś demography in the past. The settlement of a secondary contact zone in Nothofagus species around 42-44°S coincides with the phylogeographic breaks and hotspots of genetic diversity found in other plant and animal species in Patagonia

  18. Seed dormancy responses to temperature relate to Nothofagus species distribution and determine temporal patterns of germination across altitudes in Patagonia.

    PubMed

    Arana, María V; Gonzalez-Polo, Marina; Martinez-Meier, Alejandro; Gallo, Leonardo A; Benech-Arnold, Roberto L; Sánchez, Rodolfo A; Batlla, Diego

    2016-01-01

    Seeds integrate environmental cues that modulate their dormancy and germination. Although many mechanisms have been identified in laboratory experiments, their contribution to germination dynamics in existing communities and their involvement in defining species habitats remain elusive. By coupling mathematical models with ecological data we investigated the contribution of seed temperature responses to the dynamics of germination of three Nothofagus species that are sharply distributed across different altitudes in the Patagonian Andes. Seed responsiveness to temperature of the three Nothofagus species was linked to the thermal characteristics of their preferred ecological niche. In their natural distribution range, there was overlap in the timing of germination of the species, which was restricted to mid-spring. By contrast, outside their species distribution range, germination was temporally uncoupled with altitude. This phenomenon was described mathematically by the interplay between interspecific differences in seed population thermal parameters and the range in soil thermic environments across different altitudes. The observed interspecific variations in seed responsiveness to temperature and its environmental regulation, constitute a major determinant of the dynamics of Nothofagus germination across elevations. This phenomenon likely contributes to the maintenance of patterns of species abundance across altitude by placing germinated seeds in a favorable environment for plant growth. PMID:26306993

  19. Surface-bound phosphatase activity in living hyphae of ectomycorrhizal fungi of Nothofagus obliqua.

    PubMed

    Alvarez, Maricel; Godoy, Roberto; Heyser, Wolfgang; Härtel, Steffen

    2004-01-01

    We determined the location and the activity of surface-bound phosphomonoesterase (SBP) of five ectomycorrhizal (EM) fungi of Nothofagus oblique. EM fungal mycelium of Paxillus involutus, Austropaxillus boletinoides, Descolea antartica, Cenococcum geophilum and Pisolithus tinctorius was grown in media with varying concentrations of dissolved phosphorus. SBP activity was detected at different pH values (3-7) under each growth regimen. SBP activity was assessed using a colorimetric method based on the hydrolysis of p-nitrophenyl phosphate (pNPP) to p-nitrophenol phosphate (pNP) + P. A new technique involving confocal laser-scanning microscopy (LSM) was used to locate and quantify SBP activity on the hyphal surface. EM fungi showed two fundamentally different patterns of SBP activity in relation to varying environmental conditions (P-concentrations and pH). In the cases of D. antartica, A. boletinoides and C. geophilum, changes in SBP activity were induced primarily by changes in the number of SBP-active centers on the hyphae. In the cases of P. tinctorius and P. involutus, the number of SBP-active centers per μm hyphal length changed much less than the intensity of the SBP-active centers on the hyphae. Our findings not only contribute to the discussion about the role of SBP-active centers in EM fungi but also introduce LSM as a valuable method for studying EM fungi. PMID:21148871

  20. Preformation and Neoformation in Shoots of Nothofagus antarctica (G. Forster) Oerst. (Nothofagaceae) Shrubs from Northern Patagonia

    PubMed Central

    PUNTIERI, J. G.; STECCONI, M.; BARTHÉLÉMY, D.

    2002-01-01

    The size (length and diameter) and number of leaf primordia of winter buds of Nothofagus antarctica (G. Forster) Oerst. shrubs were compared with the size and number of leaves of shoots derived from buds in equivalent positions. Buds developed in two successive years were compared in terms of size and number of leaf primordia. Bud size and the number of leaf primordia per bud were greater for distal than for proximally positioned buds. Shoots that developed in the five positions closest to the distal end of their parent shoots had significantly more leaves than more proximally positioned shoots of the same parent shoots. The positive relationship between the size of a shoot and that of its parent shoot was stronger for proximal than for distal positions on the parent shoots. For each bud position on the parent shoots there were differences in the number of leaf primordia per bud between consecutive years. The correlations between the number of leaf primordia per bud and bud size, bud position and parent shoot size varied between years. Only shoots produced close to the distal end of a parent shoot developed neoformed leaves; more proximal sibling shoots consisted entirely of preformed leaves. Leaf neoformation, a process usually linked with high shoot vigour in woody plants, seems to be widespread among the relatively small shoots developed in N. antarctica shrubs, which may relate to the species’ opportunistic response to disturbance. PMID:12102521

  1. Seedling disease in Michigan

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sugar beet seedlings (24 entries of a larger genetic population constructed to dissect Rhizoctonia disease reaction in sugar beet) were screened for their response to a highly virulent isolate of Rhizoctonia solani AG 2-2. Seedlings were grown to the two-leaf stage in the greenhouse, thinned to 15 p...

  2. Size-Specific Tree Mortality Varies with Neighbourhood Crowding and Disturbance in a Montane Nothofagus Forest

    PubMed Central

    Hurst, Jennifer M.; Allen, Robert B.; Coomes, David A.; Duncan, Richard P.

    2011-01-01

    Tree mortality is a fundamental process governing forest dynamics, but understanding tree mortality patterns is challenging because large, long-term datasets are required. Describing size-specific mortality patterns can be especially difficult, due to few trees in larger size classes. We used permanent plot data from Nothofagus solandri var. cliffortioides (mountain beech) forest on the eastern slopes of the Southern Alps, New Zealand, where the fates of trees on 250 plots of 0.04 ha were followed, to examine: (1) patterns of size-specific mortality over three consecutive periods spanning 30 years, each characterised by different disturbance, and (2) the strength and direction of neighbourhood crowding effects on size-specific mortality rates. We found that the size-specific mortality function was U-shaped over the 30-year period as well as within two shorter periods characterised by small-scale pinhole beetle and windthrow disturbance. During a third period, characterised by earthquake disturbance, tree mortality was less size dependent. Small trees (<20 cm in diameter) were more likely to die, in all three periods, if surrounded by a high basal area of larger neighbours, suggesting that size-asymmetric competition for light was a major cause of mortality. In contrast, large trees (≥20 cm in diameter) were more likely to die in the first period if they had few neighbours, indicating that positive crowding effects were sometimes important for survival of large trees. Overall our results suggest that temporal variability in size-specific mortality patterns, and positive interactions between large trees, may sometimes need to be incorporated into models of forest dynamics. PMID:22046327

  3. Chemical and Antioxidant Properties of Wild Edible Mushrooms from Native Nothofagus spp. Forest, Argentina.

    PubMed

    Toledo, Carolina V; Barroetaveña, Carolina; Fernandes, Ângela; Barros, Lillian; Ferreira, Isabel C F R

    2016-01-01

    This study addresses issues regarding chemical and bioactive properties of nine wild edible mushrooms from native Nothofagus forest from Patagonia, Argentina. Macronutrients, sugars, fatty acids, tocopherols, organic acids, phenolic compounds and antioxidant properties were determined. Protein was found in high levels and varied between 3.35 g/100 g dw in Cyttaria hariotii and 22.29 g/100 g dw in Lepista nuda. All of them presented mannitol and trehalose as main sugars. Mannitol was significantly higher in Ramaria patagonica, although absent in Fistulina endoxantha, whereas trehalose predominated in Aleurodiscus vitellinus, Hydropus dusenii, Cortinarius magellanicus, C. hariotii, Grifola gargal and L. nuda, ranging from 1.15 to 10.26 g/100 g dw; it was absent in R. patagonica. The major fatty acid found was linoleic acid, followed by oleic acid and palmitic acid. All species presented oxalic and fumaric acids, while some also had malic, quinic and citric acids. Tocopherols composition was variable. Cortinarius magellanicus presented significantly higher contents of both α-tocopherol and β-tocopherol. R. patagonica presented the best results in all the antioxidant activity assays (EC50 values ≤ 1 mg/mL) and the highest content of phenolic compounds presenting gallic, p-hydroxybenzoic, p-coumaric and cinnamic acids. This study constitutes the first report on chemical composition and nutritional value of most of these edible mushroom species. Furthermore, it provides important information necessary to characterize and define the use of these species as gastronomic delicacies, functional foods and sources of bioactive compounds. PMID:27617993

  4. Solar radiation transmission in and around canopy gaps in an uneven-aged Nothofagus betuloides forest

    NASA Astrophysics Data System (ADS)

    Promis, Alvaro; Schindler, Dirk; Reif, Albert; Cruz, Gustavo

    2009-07-01

    The transmission of direct, diffuse and global solar radiation in and around canopy gaps occurring in an uneven-aged, evergreen Nothofagus betuloides forest during the growing season (October 2006-March 2007) was estimated by means of hemispherical photographs. The transmission of solar radiation into the forest was affected not only by a high level of horizontal and vertical heterogeneity of the forest canopy, but also by low angles of the sun’s path. The below-canopy direct solar radiation appeared to be variable in space and time. On average, the highest amount of transmitted direct solar radiation was estimated below the undisturbed canopy at the southeast of the gap centre. The transmitted diffuse and global solar radiation above the forest floor exhibited lower variability and, on average, both were higher at the centre of the canopy gaps. Canopy structure and stand parameters were also measured to explain the variation in the below-canopy solar radiation in the forest. The model that best fit the transmitted below-canopy direct solar radiation was a growth model, using plant area index with an ellipsoidal angle distribution as the independent variable ( R 2 = 0.263). Both diffuse and global solar radiation were very sensitive to canopy openness, and for both cases a quadratic model provided the best fit for these data ( R 2 = 0.963 and 0.833, respectively). As much as 75% and 73% of the variation in the diffuse and global solar radiation, respectively, were explained by a combination of stand parameters, namely basal area, crown projection, crown volume, stem volume, and average equivalent crown radius.

  5. REFORESTATION AND SEEDLING SYMBIONTS

    EPA Science Inventory

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

  6. Preformation and distribution of staminate and pistillate flowers in growth units of Nothofagus alpina and N. obliqua (Nothofagaceae)

    PubMed Central

    Puntieri, Javier G.; Grosfeld, Javier E.; Heuret, Patrick

    2009-01-01

    Background and Aims The distribution and differentiation times of flowers in monoecious wind-pollinated plants are fundamental for the understanding of their mating patterns and evolution. Two closely related South American Nothofagus species were compared with regard to the differentiation times and positions of staminate and pistillate flowers along their parent growth units (GUs) by quantitative means. Methods Two samples of GUs that had extended in the 2004–2005 growing season were taken in 2005 and 2006 from trees in the Lanín National Park, Patagonia, Argentina. For the first sample, axillary buds of the parent GUs were dissected and the leaf, bud and flower primordia of these buds were identified. The second sample included all branches derived from the parent GUs in the 2005–2006 growing season. Key Results Both species developed flowering GUs with staminate and/or pistillate flowers; GUs with both flower types were the most common. The position of staminate flowers along GUs was similar between species and close to the proximal end of the GUs. Pistillate flowers were developed more distally along the GUs in N. alpina than in N. obliqua. In N. alpina, the nodes bearing staminate and pistillate flowers were separated by one to several nodes with axillary buds, something not observed in N. obliqua. Markovian models supported this between-species difference. Flowering GUs, including all of their leaves and flowers were entirely preformed in the winter buds. Conclusions Staminate and pistillate flowers of N. alpina and N. obliqua are differentiated at precise locations on GUs in the growing season preceding that of their antheses. The differences between N. alpina and N. obliqua (and other South American Nothofagus species) regarding flower distribution might relate to the time of anthesis of each flower type and, in turn, to the probabilities of self-pollination at the GU level. PMID:19033286

  7. Germination and seedling development

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  8. The southernmost Andean Mountain soils: a toposequence from Nothofagus Forest to Sub Antarctic Tundra at Ushuaia, Tierra del Fuego

    NASA Astrophysics Data System (ADS)

    Firme Sá, Mariana M.; Schaefer, Carlos E.; Loureiro, Diego C.; Simas, Felipe N.; Francelino, Marcio R.; Senra, Eduardo O.

    2015-04-01

    Located at the southern tip of the Fuegian Andes Cordilhera, the Martial glacier witnessed a rapid process of retreat in the last century. Up to now little is known about the development and genesis of soils of this region. A toposequence of six soils, ranging from 430-925 m a.s.l, was investigated, with emphasis on genesis, chemical and mineralogical properties. The highest, youngest soil is located just below the Martial Glacier Martial Sur sector, and the lowest soils occur on sloping moraines under Nothofagus pumilio forests. Based on chemical, physical and mineralogical characteristics, the soils were classified according to the Soil taxonomy, being keyed out as Inceptisols and Entisols. Soil parent material of the soil is basically moraines, in which the predominant lithic components dominated by metamorphic rocks, with allochthonous contributions of wind-blown materials (very small fragments of volcanic glass) observed by hand lens in all horizons, except the highest profile under Tundra. In Nothofagus Deciduous Forests at the lowest part of the toposequence, poorly developed Inceptisols occur with Folistic horizons, with mixed "andic" and "spodic" characters, but with a predominance of andosolization (Andic Drystrocryepts). Under Tundra vegetation, Inceptisols are formed under hydromorphism and andosolization processes (Oxiaquic Dystrocrepts and Typic Dystrocrepts). On highland periglacial environments, soils without B horizon with strong evidence of cryoturbation and cryogenesis occur, without present-day permafrost down to 2 meters (Typic Cryorthents and Lithic Haploturbels). The mountain soils of Martial glacier generalize young, stony and rich in organic matter, with the exception of barely vegetated Tundra soils at higher altitudes. The forest soils are more acidic and have higher Al3+activity. All soils are dystrophic, except for the highest profile of the local periglacial environment. The organic carbon amounts are higher in forest soils and

  9. Genetic Diversity in Nothofagus alessandrii (Fagaceae), an Endangered Endemic Tree Species of the Coastal Maulino Forest of Central Chile

    PubMed Central

    Torres-Díaz, Cristian; Ruiz, Eduardo; González, Fidelina; Fuentes, Glenda; Cavieres, Lohengrin A.

    2007-01-01

    Background and Aims The endemic tree Nothofagus alessandrii (Fagaceae) has been historically restricted to the coastal range of Region VII of central Chile, and its forests have been increasingly destroyed and fragmented since the end of the 19th century. In this study, the patterns of within- and among-population genetic diversity in seven fragments of this endangered narrowly endemic tree were examined. Methods Allozyme electrophoresis of seven loci of N. alessandrii was used to estimate genetic diversity, genetic structure and gene flow. Key Results High levels of genetic diversity were found as shown by mean expected heterozygosity (He = 0·182 ± 0·034), percentage of polymorphic loci (Pp = 61·2 %), mean number of alleles per locus (A = 1·8) and mean number of alleles per polymorphic locus (Ap = 2·3). Genetic differentiation was also high (GST = 0·257 and Nm = 0·7). These values are high compared with more widespread congeneric species. Conclusions Despite its endemic status and restricted geographical range N. alessandrii showed high levels of genetic diversity. The observed patterns of diversity are explained in part by historical processes and more recent human fragmentation. PMID:17513870

  10. Yeast and yeast-like fungi associated with dry indehiscent fruits of Nothofagus nervosa in Patagonia, Argentina.

    PubMed

    Fernández, Natalia V; Mestre, M Cecilia; Marchelli, Paula; Fontenla, Sonia B

    2012-04-01

    Nothofagus nervosa (Raulí) is a native tree species that yields valuable timber. It was overexploited in the past and is currently included in domestication and conservation programs. Several research programs have focused on the characterization of epiphytic microorganisms because it has been demonstrated that they can affect plant-pathogen interactions and/or promote plant growth. Although the microbial ecology of leaves has been well studied, less is known about microorganisms occurring on seeds and noncommercial fruits. In this work, we analyzed the yeast and yeast-like fungi present on N. nervosa fruits destined for the propagation of this species, as well as the effects of fruit preservation and seed dormancy-breaking processes on fungal diversity. Morphological and molecular methods were used, and differences between fungal communities were analyzed using a similarity index. A total of 171 isolates corresponding to 17 species were recovered, most of which belong to the phylum Ascomycota. The majority of the species develop mycelia, produce pigments and mycosporines, and these adaptation strategies are discussed. It was observed that the preservation process considerably reduced yeast and yeast-like fungal diversity. This is the first study concerning microbial communities associated with this ecologically and economically important species, and the information presented is relevant to domestication programs. PMID:22224476

  11. Are the oxygen isotopic compositions of Fitzroya cupressoides and Nothofagus pumilio cellulose promising proxies for climate reconstructions in northern Patagonia?

    NASA Astrophysics Data System (ADS)

    Lavergne, Aliénor; Daux, Valérie; Villalba, Ricardo; Pierre, Monique; Stievenard, Michel; Vimeux, Françoise; Srur, Ana Marina

    2016-03-01

    Tree ring δ18O chronologies from two native species (Fitzroya cupressoides and Nothofagus pumilio) in northern Patagonia were developed to assess their potential for paleoclimate reconstructions. The five annually resolved cellulose δ18O chronologies (two for F. cupressoides and three for N. pumilio) are located on the Andes along the steep west-to-east precipitation gradient. Over the common 60 years long interval, the five site-δ18Ocell chronologies exhibit a strong common signal as indicated by the significant mean intercorrelation (r = 0.61, p < 0.05) and the high percentage (65%) of total variance explained by the first empirical orthogonal function. Although correlation analyses reveal that the two mean species-δ18Ocell chronologies are mainly modulated by December-May temperature, the N. pumilio chronology shows a greater sensitivity to record temperature variations (r = 0.57, p < 0.05). The δ18Ocell of N. pumilio contains a regional temperature signal representative of a large area in southern South America under the influence of the Southern Annular Mode. This study indicates that δ18Ocell in N. pumilio is a promising proxy to reconstruct past variations in temperature in South America south of 38°S.

  12. Seedling Disease Survey in Michigan

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  13. Genetic differentiation in spite of high gene flow in the dominant rainforest tree of southeastern Australia, Nothofagus cunninghamii.

    PubMed

    Duncan, C J; Worth, J R P; Jordan, G J; Jones, R C; Vaillancourt, R E

    2016-01-01

    Nothofagus cunninghamii is a long-lived, wind-pollinated tree species that dominates the cool temperate rainforests of southeastern Australia. The species' distribution is more or less continuous in western Tasmania but is fragmented elsewhere. However, it is unknown whether this fragmentation has affected the species' genetic architecture. Thus, we examined N. cunninghamii using 12 nuclear microsatellites and 633 individuals from 18 populations spanning the species' natural range. Typical of wind-pollinated trees, there was low range-wide genetic structure (FST=0.04) consistent with significant gene flow across most of the species' range. However, gene flow was not high enough to overcome the effects of drift across some disjunctions. Victorian populations (separated from Tasmania by the 240 km wide Bass Strait) formed a genetic group distinct from Tasmanian populations, had lower diversity (mean allelic richness (Ar)=5.4 in Victoria versus 6.9 in Tasmania) and were significantly more differentiated from one another than those in Tasmania (FST=0.045 in Victoria versus 0.012 in Tasmania). Evidence for bottlenecking was found in small populations that were at least 20 km from other populations. Interestingly, we found little divergence in microsatellite markers between the extremes of genetically based morphological and physiological altitudinal clines suggesting adaptive differentiation is strongly driven by selection because it is likely to be occurring in the presence of gene flow. Even though the cool temperate rainforests of Australia are highly relictual, the species is relatively robust to population fragmentation due to high levels of genetic diversity and gene flow, especially in Tasmania. PMID:26350630

  14. No evidence of carbon limitation with tree age and height in Nothofagus pumilio under Mediterranean and temperate climate conditions

    PubMed Central

    Piper, Frida I.; Fajardo, Alex

    2011-01-01

    Background and Aims Trees universally decrease their growth with age. Most explanations for this trend so far support the hypothesis that carbon (C) gain becomes limited with age; though very few studies have directly assessed the relative reductions of C gain and C demand with tree age. It has also been suggested that drought enhances the effect of C gain limitation in trees. Here tests were carried out to determine whether C gain limitation is causing the growth decay with tree age, and whether drought accentuates its effect. Methods The balance between C gain and C demand across tree age and height ranges was estimated. For this, the concentration of non-structural carbohydrates (NSCs) in stems and roots of trees of different ages and heights was measured in the deciduous temperate species Nothofagus pumilio. An ontogenetic decrease in NSCs indicates support for C limitation. Furthermore, the importance of drought in altering the C balance with ontogeny was assessed by sampling the same species in Mediterranean and humid climate locations in the southern Andes of Chile. Wood density (WD) and stable carbon isotope ratios (δ13C) were also determined to examine drought constraints on C gain. Key Results At both locations, it was effectively found that tree growth ultimately decreased with tree age and height. It was found, however, that NSC concentrations did not decrease with tree age or height when WD was considered, suggesting that C limitation is not the ultimate mechanism causing the age/height-related declining tree growth. δ13C decreased with tree age/height at the Mediterranean site only; drought effect increased with tree age/height, but this pattern was not mirrored by the levels of NSCs. Conclusions The results indicate that concentrations of C storage in N. pumilio trees do not decrease with tree age or height, and that reduced C assimilation due to summer drought does not alter this pattern. PMID:21852277

  15. Multi-stemmed trees of Nothofagus pumilio second-growth forest in Patagonia are formed by highly related individuals

    PubMed Central

    Till-Bottraud, Irène; Fajardo, Alex; Rioux, Delphine

    2012-01-01

    Background and Aims Multi-stemmed trees (tree clusters) in Nothofagus pumilio, a dominant tree species in Patagonia, are very uncommon and are restricted to the edge of second-growth forests following human-provoked fires. No vegetative reproduction has been reported so far. The genetic structure of multi-stemmed trees of this species was investigated and it was hypothesized that genets within a cluster were more closely related than average in the population. Methods Fifteen clusters (composed of at least three purported stems) and 15 single trees were sampled at the edge of a second-growth forest and genotyped using two amplified fragment length polymorphism (AFLP) primer pairs. We obtained 119 polymorphic markers that allowed clonality to be determined, together with sibship structure and relatedness among samples. Key Results Clonality was detected in seven clusters but all clusters had at least two different genotypes. Full sibs were found exclusively within clusters and in all clusters. Within a cluster, stems that were not identified as full sibs were often half sibs. Relatedness values for the full sibs and half sibs were higher than the theoretical values of 0·5 and 0·25 but the relatedness between clusters was very low. Conclusions Tree clusters that are merged at the edge of the second-growth forest of N. pumilio are composed of stems of the same genotype and of other genotypes that are highly related (but not always). It is suggested that this peculiar genetic structure results from a combination of several causes, including selection for merging of related individuals. PMID:22782238

  16. Solar UV-B radiation affects leaf quality and insect herbivory in the southern beech tree Nothofagus antarctica.

    PubMed

    Rousseaux, M Cecilia; Julkunen-Tiitto, Riitta; Searles, Peter S; Scopel, Ana L; Aphalo, Pedro J; Ballaré, Carlos L

    2004-03-01

    We examined the effects of solar ultraviolet-B (UV-B) radiation on plant-insect interactions in Tierra del Fuego (55 degrees S), Argentina, an area strongly affected by ozone depletion because of its proximity to Antarctica. Solar UV-B under Nothofagus antarctica branches was manipulated using a polyester plastic film to attenuate UV-B (uvb-) and an Aclar film to provide near-ambient UV-B (uvb+). The plastic films were placed on both north-facing (i.e., high solar radiation in the Southern Hemisphere) and south-facing branches. Insects consumed 40% less leaf area from north- than from south-facing branches, and at least 30% less area from uvb+ branches than from uvb- branches. The reduced herbivory on leaves from uvb+ branches occurred for both branch orientations. Leaf mass per area increased and relative water content decreased on north- versus south-facing branches, while no differences were apparent between the UV-B treatments. Solar UV-B did lead to lower gallic acid concentration and higher flavonoid aglycone concentration in uvb+ leaves relative to uvb- leaves. Both the flavonoid aglycone and quercetin-3-arabinopyranoside were higher on north-facing branches. In laboratory preference experiments, larvae of the dominant insect in the natural community, Geometridae "Brown" (Lepidoptera), consumed less area from field-grown uvb+ leaves than from uvb- leaves in 1996-97, but not in 1997-98. Correlation analyses suggested that the reduction in insect herbivory in the field under solar UV-B may be mediated in part by the UV-B effects on gallic acid and flavonoid aglycone. PMID:14740287

  17. Space Station Live: Seedling Growth

    NASA Video Gallery

    Public Affairs Officer Lori Meggs talks with Carol Jacobs, payload operations director at the Marshall Space Flight Center's POIC, about the Seedling Growth experiment talking place aboard the Inte...

  18. Tree-Ring Stable Isotopes Reveal Twentieth-Century Increases in Water-Use Efficiency of Fagus sylvatica and Nothofagus spp. in Italian and Chilean Mountains

    PubMed Central

    Tognetti, Roberto; Lombardi, Fabio; Lasserre, Bruno; Cherubini, Paolo; Marchetti, Marco

    2014-01-01

    Changes in intrinsic water use efficiency (iWUE) were investigated in Fagus sylvatica and Nothofagus spp. over the last century. We combined dendrochronological methods with dual-isotope analysis to investigate whether atmospheric changes enhanced iWUE of Fagus and Nothofagus and tree growth (basal area increment, BAI) along latitudinal gradients in Italy and Chile. Post-maturation phases of the trees presented different patterns in δ13C, Δ13C, δ18O, Ci (internal CO2 concentration), iWUE, and BAI. A continuous enhancement in isotope-derived iWUE was observed throughout the twentieth century, which was common to all sites and related to changes in Ca (ambient CO2 concentration) and secondarily to increases in temperature. In contrast to other studies, we observed a general increasing trend of BAI, with the exception of F. sylvatica in Aspromonte. Both iWUE and BAI were uncoupled with the estimated drought index, which is in agreement with the absence of enduring decline in tree growth. In general, δ13C and δ18O showed a weak relationship, suggesting the major influence of photosynthetic rate on Ci and δ13C, and the minor contribution of the regulation of stomatal conductance to iWUE. The substantial warming observed during the twentieth century did not result in a clear pattern of increased drought stress along these latitudinal transects, because of the variability in temporal trends of precipitation and in specific responses of populations. PMID:25398040

  19. Tree-ring stable isotopes reveal twentieth-century increases in water-use efficiency of Fagus sylvatica and Nothofagus spp. in Italian and Chilean mountains.

    PubMed

    Tognetti, Roberto; Lombardi, Fabio; Lasserre, Bruno; Cherubini, Paolo; Marchetti, Marco

    2014-01-01

    Changes in intrinsic water use efficiency (iWUE) were investigated in Fagus sylvatica and Nothofagus spp. over the last century. We combined dendrochronological methods with dual-isotope analysis to investigate whether atmospheric changes enhanced iWUE of Fagus and Nothofagus and tree growth (basal area increment, BAI) along latitudinal gradients in Italy and Chile. Post-maturation phases of the trees presented different patterns in δ13C, Δ13C, δ18O, Ci (internal CO2 concentration), iWUE, and BAI. A continuous enhancement in isotope-derived iWUE was observed throughout the twentieth century, which was common to all sites and related to changes in Ca (ambient CO2 concentration) and secondarily to increases in temperature. In contrast to other studies, we observed a general increasing trend of BAI, with the exception of F. sylvatica in Aspromonte. Both iWUE and BAI were uncoupled with the estimated drought index, which is in agreement with the absence of enduring decline in tree growth. In general, δ13C and δ18O showed a weak relationship, suggesting the major influence of photosynthetic rate on Ci and δ13C, and the minor contribution of the regulation of stomatal conductance to iWUE. The substantial warming observed during the twentieth century did not result in a clear pattern of increased drought stress along these latitudinal transects, because of the variability in temporal trends of precipitation and in specific responses of populations. PMID:25398040

  20. Beet Rust and Seedling Rust

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Beet rust, caused by Uromyces betae, can cause pustules on most beet types, and can be a problem in various beet growing areas. Seedling rust, caused by Puccinia subnitens can cause lesions on young beets, primarily on cotyledons, and does not cause economic damage. This chapter describes the dise...

  1. TWO NEW SPECIES OF MEALYBUGS FROM PATAGONIA, ARGENTINA (HEMIPTERA: COCCOIDEA: PSEUDOCOCCIDAE)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two new species of mealybugs have been discovered in the Patagonia Region of Argentina collected on Nothofagus dombeyi and Stipa sp. Adult females and available immature stages of each species are described and illustrated and are compared with other mealybugs from the area....

  2. Field measurement of cotton seedling evapotranspiration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Information on cotton evapotranspiration (ET) during the seedling growth stage and under field conditions is scarce because ET is a difficult parameter to measure. Our objective was to use weighable lysimeters to measure daily values of cotton seedling ET. We designed and built plastic weighable mic...

  3. Living on the edge: adaptive and plastic responses of the tree Nothofagus pumilio to a long-term transplant experiment predict rear-edge upward expansion.

    PubMed

    Mathiasen, Paula; Premoli, Andrea C

    2016-06-01

    Current climate change affects the competitive ability and reproductive success of many species, leading to local extinctions, adjustment to novel local conditions by phenotypic plasticity or rapid adaptation, or tracking their optima through range shifts. However, many species have limited ability to expand to suitable areas. Altitudinal gradients, with abrupt changes in abiotic conditions over short distances, represent "natural experiments" for the evaluation of ecological and evolutionary responses under scenarios of climate change. Nothofagus pumilio is the tree species which dominates as pure stands the montane forests of Patagonia. We evaluated the adaptive value of variation in quantitative traits of N. pumilio under contrasting conditions of the altitudinal gradient with a long-term reciprocal transplant experimental design. While high-elevation plants show little response in plant, leaf, and phenological traits to the experimental trials, low-elevation ones show greater plasticity in their responses to changing environments, particularly at high elevation. Our results suggest a relatively reduced potential for evolutionary adaptation of high-elevation genotypes, and a greater evolutionary potential of low-elevation ones. Under global warming scenarios of forest upslope migration, high-elevation variants may be outperformed by low-elevation ones during this process, leading to the local extinction and/or replacement of these genotypes. These results challenge previous models and predictions expected under global warming for altitudinal gradients, on which the leading edge is considered to be the upper treeline forests. PMID:26868524

  4. Seedling Diversity and the Homologies of Seedling Organs in the Order Poales (Monocotyledons)

    PubMed Central

    Tillich, Hans-Jürgen

    2007-01-01

    Background and Aims Seedlings of monocots are much more diverse than those of other angiosperms, often with very derived character states. This makes morphological interpretation difficult. The morphology of seedlings of most of the 16 families of the Poales alliance are only incompletely known. The present study aims first to develop an unambiguous terminology for the description of monocotyledonous seedlings. This makes possible clear morphological comparisons and the use of homologous terms for organs. Finally, plotting of well defined characters onto a molecular tree allows the polarization of character states. Method Seedlings were grown in Petri dishes on moist filter paper under permanent light conditions and analysed using light and scanning electron microscopy. Only seeds collected at natural habitats or from plants with a well documented source were used. Seedling vouchers are deposited in the alcohol collection of Monocot seedlings in the Botanische Staatssammlung München (M). Key Results Based on an unambiguous terminology, seedlings of a great number of genera are described and presented as figures, representing all families of Poales except Ecdeiocoleaceae. Seedlings of Rapateaceae, Joinvilleaceae and Mayacaceae are described for the first time. Morphological comparisons reveal a plausible interpretation of even very modified organ structures, including those of the grass seedling. Conclusions This study demonstrates that detailed studies of seedling morphology can provide interesting morphological insights and also new facts for phylogenetic analyses. However, the morphological diversity of seedlings in the monocots is as yet incompletely known, and in some, e.g. Alismatales or Zingiberales, the seedling structure is particularly poorly understood in terms of comparative morphology. PMID:17933843

  5. Continental and local climatic influences on hydrology of eucalypt-Nothofagus ecosystems revealed by δ2H, δ13C, and δ18O of ecosystem samples

    NASA Astrophysics Data System (ADS)

    Pfautsch, Sebastian; Gessler, Arthur; Rennenberg, Heinz; Weston, Christopher J.; Adams, Mark A.

    2010-03-01

    Marrying knowledge of variation in large-scale climatic parameters such as rainfall and evaporation to physiological ecology has long been argued as a powerful approach to advancing understanding of hydrology of catchments. Widely used hydrological models for assessing water yield depend on key plant attributes such as whether or not plant water use is coupled to atmospheric and/or soil water status. We analyzed δ2H and δ18O signatures of long-term rainwater collections from coastal sites near Melbourne, Australia, and in northwest Tasmania and compared them with their counterparts in rainwater, stream water, soil water, and twig water data collected over a 2 year period from south facing Eucalyptus-Nothofagus forests in the Cement Creek catchment of Mt. Donna Buang, about 70 km east of the city of Melbourne. Within the catchment, progressive evaporative enrichment among rain, soil, and twig water accounted for observed δ2H and δ18O signatures. We observed a major shift in both δ2H and δ18O signatures of rain and stream water between 2001/2002 and 2003. The shift was likely due to changes in atmospheric conditions and especially relative contributions to rainwater from oceanic and continental sources. Our plant isotope data argue strongly that radiation, not water, is a primary limitation for Nothofagus on Mt. Donna Buang. The δ18O and δ13C signatures of foliage varied with season and with topography. For the wettest and driest years in the 1978-2000 record, strong and consistent altitudinal gradients in δ13C of tree rings had a slope of between 4‰ and 5‰ km-1 of altitude. Our data highlight the importance of background (e.g., rainfall and atmospheric CO2) isotope data to interpretation of plant isotope data. Taken together with the literature, our isotope data lead us to conclude that (1) in periods of close to average rainfall, the observed meteoric water line at Mt. Donna Buang and at other stations in southeast Australia departs strongly in slope

  6. Population genetic structure, genetic diversity, and natural history of the South American species of Nothofagus subgenus Lophozonia (Nothofagaceae) inferred from nuclear microsatellite data

    PubMed Central

    Vergara, Rodrigo; Gitzendanner, Matthew A; Soltis, Douglas E; Soltis, Pamela S

    2014-01-01

    The effect of glaciation on the levels and patterns of genetic variation has been well studied in the Northern Hemisphere. However, although glaciation has undoubtedly shaped the genetic structure of plants in the Southern Hemisphere, fewer studies have characterized the effect, and almost none of them using microsatellites. Particularly, complex patterns of genetic structure might be expected in areas such as the Andes, where both latitudinal and altitudinal glacial advance and retreat have molded modern plant communities. We therefore studied the population genetics of three closely related, hybridizing species of Nothofagus (N. obliqua, N. alpina, and N. glauca, all of subgenus Lophozonia; Nothofagaceae) from Chile. To estimate population genetic parameters and infer the influence of the last ice age on the spatial and genetic distribution of these species, we examined and analyzed genetic variability at seven polymorphic microsatellite DNA loci in 640 individuals from 40 populations covering most of the ranges of these species in Chile. Populations showed no significant inbreeding and exhibited relatively high levels of genetic diversity (HE = 0.502–0.662) and slight, but significant, genetic structure (RST = 8.7–16.0%). However, in N. obliqua, the small amount of genetic structure was spatially organized into three well-defined latitudinal groups. Our data may also suggest some introgression of N. alpina genes into N. obliqua in the northern populations. These results allowed us to reconstruct the influence of the last ice age on the genetic structure of these species, suggesting several centers of genetic diversity for N. obliqua and N. alpina, in agreement with the multiple refugia hypothesis. PMID:25360279

  7. Intraspecific Relationships among Wood Density, Leaf Structural Traits and Environment in Four Co-Occurring Species of Nothofagus in New Zealand

    PubMed Central

    Richardson, Sarah J.; Allen, Robert B.; Buxton, Rowan P.; Easdale, Tomás A.; Hurst, Jennifer M.; Morse, Christopher W.; Smissen, Rob D.; Peltzer, Duane A.

    2013-01-01

    Plant functional traits capture important variation in plant strategy and function. Recent literature has revealed that within-species variation in traits is greater than previously supposed. However, we still have a poor understanding of how intraspecific variation is coordinated among different traits, and how it is driven by environment. We quantified intraspecific variation in wood density and five leaf traits underpinning the leaf economics spectrum (leaf dry matter content, leaf mass per unit area, size, thickness and density) within and among four widespread Nothofagus tree species in southern New Zealand. We tested whether intraspecific relationships between wood density and leaf traits followed widely reported interspecific relationships, and whether variation in these traits was coordinated through shared responses to environmental factors. Sample sites varied widely in environmental variables, including soil fertility (25–900 mg kg–1 total P), precipitation (668–4875 mm yr–1), temperature (5.2–12.4 °C mean annual temperature) and latitude (41–46 °S). Leaf traits were strongly correlated with one another within species, but not with wood density. There was some evidence for a positive relationship between wood density and leaf tissue density and dry matter content, but no evidence that leaf mass or leaf size were correlated with wood density; this highlights that leaf mass per unit area cannot be used as a surrogate for component leaf traits such as tissue density. Trait variation was predicted by environmental factors, but not consistently among different traits; e.g., only leaf thickness and leaf density responded to the same environmental cues as wood density. We conclude that although intraspecific variation in wood density and leaf traits is strongly driven by environmental factors, these responses are not strongly coordinated among functional traits even across co-occurring, closely-related plant species. PMID:23527041

  8. DESIGN ISSUES FOR EVALUATING SEEDLING EXPOSURE STUDIES

    EPA Science Inventory

    Tree seedling studies, covering a wide range of experimental conditions in pollutant treatment, species, facilities, and exposure regimes, have become commonplace in forestry research for assessing the actual and potential environmental effects of air pollutants on forest ecosyst...

  9. Line-scan inspection of conifer seedlings

    NASA Astrophysics Data System (ADS)

    Rigney, Michael P.; Kranzler, Glenn A.

    1993-05-01

    Almost two billion conifer seedlings are produced in the U.S. each year to support reforestation efforts. Seedlings are graded manually to improve viability after transplanting. Manual grading is labor-intensive and subject to human variability. Our previous research demonstrated the feasibility of automated tree seedling inspection with machine vision. Here we describe a system based on line-scan imaging, providing a three-fold increase in resolution and inspection rate. A key aspect of the system is automatic recognition of the seedling root collar. Root collar diameter, shoot height, and projected shoot and root areas are measured. Sturdiness ratio and shoot/root ratio are computed. Grade is determined by comparing measured features with pre-defined set points. Seedlings are automatically sorted. The precision of machine vision and manual measurements was determined in tests at a commercial forest nursery. Manual measurements of stem diameter, shoot height, and sturdiness ratio had standard deviations three times those of machine vision measurements. Projected shoot area was highly correlated (r2 equals 0.90) with shoot volume. Projected root area had good correlation (r2 equals 0.80) with root volume. Seedlings were inspected at rates as high as ten per second.

  10. Clinorotation affects soybean seedling morphology

    NASA Technical Reports Server (NTRS)

    Hilaire, Emmanuel; Guikema, James A.; Brown, Christopher S.

    1995-01-01

    Although spaceflight does not appear to significantly affect seed germination, it can influence subsequent plant growth. On STS-3 and SL-2, decreased growth (measured as plant length, fresh weight, and dry weight) was noted for pine, oat, and mung bean. In the CHROMEX-01 and 02 experiments with Haplopappus and in the CHROMEX-03 experiment with Arabidopsis, enhanced root growth was noted in the space-grown plants. In the CHROMEX-04 experiments with wheat, both leaf fresh weight and leaf area were diminished in the space-grown plants but there was no difference in total plant height (CS Brown, HG Levine, and AD Krikorian, unpublished data). These data suggest that microgravity impacts growth by whole plant partitioning of the assimilates. The objective of the present study was to determine the influence of clinorotation on the growth and the morphology of soybean seedlings grown in the Biological Research In Canister (BRIC) flight hardware. This experiment provided baseline data for a spaceflight experiment (BRIC-3) flown on STS-63 (February 3-11, 1995).

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

    SciTech Connect

    McDonald, P.M.; Fiddler, G.O. ); Kitzmiller, J.H. . Chico Tree Improvement Center)

    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 seedlings 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.

  12. Anaerobic metabolism in Brassica seedlings

    NASA Astrophysics Data System (ADS)

    Park, Myoung-Ryoul; Hasenstein, Karl H.

    Germination typically depends on oxidative respiration. The lack of convection under space conditions may create hypoxic or conditions during seed germination. We investigated the effect of reduced oxygen on seed germination and metabolism to understand how metabolic constraints affect seed growth and responsiveness to reorientation. Germination was completely inhibited when seeds were imbibed in the absence of oxygen; germination occurred at 5% oxygen and higher levels. Adding oxygen after 72 h resulted in immediate germination (protrusion of the radicle). Hypoxia typically activates alcohol dehydrogenase (ADH, EC 1.1.1.1) and lactate dehydrogenase (LDH, EC 1.1.1.27) which produce ethanol and/or L-lactate, respectively. We report on the expression of ADH1 and LDH1, and changes in total soluble sugars, starch, pH, and L-lactate in seedlings grown at 28°C in 0, 2.5, 5, 10% and ambient (21%) oxygen conditions as controls. The highest consumption (lowest level) of sugars was seen at 0% oxygen but the lowest level of starch occurred 24 h after imbibition under ambient condition. Expression levels of ADH1 in ambient oxygen condition increased within 24 h but increased threefold under hypoxic conditions; LDH1 increased up to 8-fold under hypoxia compared to controls but ADH1 and LDH1 were less expressed as the oxygen levels increased. The intracellular pH of seeds decreased as the content of L-lactate increased for all oxygen concentrations. These results indicate that germination of Brassica is sensitive to oxygen levels and that oxygen availability during germination is an important factor for metabolic activities. (Supported by NASA grant NNX10AP91G)

  13. Seedling growth and development on space shuttle

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  14. USE OF SEWAGE SLUDGE FOR FOREST-TREE SEEDLING PRODUCTION

    EPA Science Inventory

    Research was undertaken to determine the beneficial and harmful effects of using dewatered, digested sewage sludge in: (1) containerized production of forest tree seedlings, (2) tree seedling production in a conventional outdoor nursery, (3) establishment and growth of transplant...

  15. STATISTICAL ISSUES FOR SEEDLING STUDIES IN AIR POLLUTION RESEARCH

    EPA Science Inventory

    By the very nature that seedlings represent the future forests, they are an important population for exposure studies. he experimental conditions for seedling studies cover a wide range of treatment combinations, facilities, and exposure regimes. he experimental utilization of ex...

  16. Changes of nucleic acids of wheat seedlings under spaceflight conditions

    NASA Technical Reports Server (NTRS)

    Sytnyk, K. M.; Musatenko, L. I.

    1983-01-01

    The effects of space flight on the growth of wheat seedlings and their nucleic acid content were studied. It was shown that both space and ground seedlings have almost the same appearance, dry weight and nucleic acid content in the root, coleoptile and leaves. The only difference found is in the RNA and DNA content, which is twice as much in the ground seedling apices as in the space-grown seedlings.

  17. Fusarium wilt of Prunus armeniaca seedlings.

    PubMed

    Afifi, A F

    1977-01-01

    Fusarium solani (Mart.) Sacc. was found to be the causal pathogen of Fusarium wilt of Prunus armeniaca seedlings. The fungus pathogenicity could be correlated with the increase in its mycelial growth and conidial germination under the influence of the host root exudates, volatile and gaseous exudates of either germinating seeds or roots, and the content of the host seedlings. Chromatographic and biological detection for indol derivatives in host root exudates indicated the presence of beta-indolacetic acid and indol-3-carbonic acid. Benzaldehyde, acetaldehyde, ethanol, ethylene, in addition to carbon dioxide, were among the volatile and gaseous exudates of either germinating seeds or roots of the host. PMID:878711

  18. Rhizoctonia seedling damping-off in sugar beet in Michigan

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rhizoctonia solani is an important seedling pathogen of sugar beet, causing damping-off following seedling emergence. Anastomosis group (AG)-4 has been the primary seedling pathogen reported on sugar beet, however, recent screening has found high incidence of infection by AG-2-2. Isolations of R. so...

  19. Analysis for an environmental friendly seedling breeding system

    NASA Astrophysics Data System (ADS)

    Qu, Y. H.; Wei, X. M.; Hou, Y. F.; Chen, B.; Chen, G. Q.; Lin, C.

    2009-04-01

    Most seedlings of crops are produced in solar greenhouse or nursery, from which some problems about energy waste and environment pollution arise. This study aims at investigating the characteristics and effect of an environmental friendly type seedling breeding system. The results demonstrate that crops can grow with a short period and little pollution in the new seedling breeding system with total manpower controllable environment that is not influenced by geography, climate and other natural conditions. By multilayer, nonplanar seedling breeding and annual batches arrangement, utilization ratio of unit area land and seedlings yield can be improved for several times and even more than 10 times. Conclusions can be obtained from the tomato seedling breeding experiments: (1) each growth index of tomato seedlings that are under the conditions of 291 μmol/m2 s artificial illumination intensity is remarkably better than those produced in greenhouse with natural lights. (2) The environment of the seedling breeding system can be accurately controlled. The segmented temperature changed management can be applied according to the photosynthetic characteristics of plants, and not affected by the outside environment, which makes each growth index of tomato seedling constant in different seasons. The seedlings thus grow strong and can achieve the level of commodity seedlings after 20-30 days. (3) The temperature and humidity environment of the seedling breeding system can be accurately controlled according to plants growth demands.

  20. Seed Mucilage Improves Seedling Emergence of a Sand Desert Shrub

    PubMed Central

    Yang, Xuejun; Baskin, Carol C.; Baskin, Jerry M.; Liu, Guangzheng; Huang, Zhenying

    2012-01-01

    The success of seedling establishment of desert plants is determined by seedling emergence response to an unpredictable precipitation regime. Sand burial is a crucial and frequent environmental stress that impacts seedling establishment on sand dunes. However, little is known about the ecological role of seed mucilage in seedling emergence in arid sandy environments. We hypothesized that seed mucilage enhances seedling emergence in a low precipitation regime and under conditions of sand burial. In a greenhouse experiment, two types of Artemisia sphaerocephala achenes (intact and demucilaged) were exposed to different combinations of burial depth (0, 5, 10, 20, 40 and 60 mm) and irrigation regimes (low, medium and high, which simulated the precipitation amount and frequency in May, June and July in the natural habitat, respectively). Seedling emergence increased with increasing irrigation. It was highest at 5 mm sand burial depth and ceased at burial depths greater than 20 mm in all irrigation regimes. Mucilage significantly enhanced seedling emergence at 0, 5 and 10 mm burial depths in low irrigation, at 0 and 5 mm burial depths in medium irrigation and at 0 and 10 mm burial depths in high irrigation. Seed mucilage also reduced seedling mortality at the shallow sand burial depths. Moreover, mucilage significantly affected seedling emergence time and quiescence and dormancy percentages. Our findings suggest that seed mucilage plays an ecologically important role in successful seedling establishment of A. sphaerocephala by improving seedling emergence and reducing seedling mortality in stressful habitats of the sandy desert environment. PMID:22511952

  1. ACID FOG EFFECTS ON CONIFER SEEDLINGS

    EPA Science Inventory

    Experiments were performed to assess the effects of acid fog on foliar injury, biomass production, and nutrient leaching in selected conifers. ne-year old seedlings of Pseudotsuga menzieii, Pinus ponderosa, Tsuga heterophylla and Thuja plicata were exposed episodically to fog eve...

  2. Rhizoctonia seedling disease on sugar beet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rhizoctonia seedling damping-off can cause losses in sugar beet as well as providing inoculum for later root rot. The disease is caused by Rhizoctonia solani. The pathogen has several subgroups, anastomosis groups (AG), of which AG-4 has historically been associated with damping-off, while AG-2-2 is...

  3. Nursery performance of peach seedling rootstocks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The nursery performance of a cross-section of both historically important and current commercial peach [Prunus persica (L.) Batsch] seedling type rootstocks was studied over three growing seasons at six nurseries serving the southeastern US peach industry. Rootstock lines differed significantly in ...

  4. Rhizoctonia seed, seedling, and wet root rot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wet root rot caused by Rhizoctonia solani Kühn can cause seed and seedling rot of both lentil and chickpea as well as many other agricultural crops worldwide. The pathogen is favored in cool, sandy soil with high organic matter under no-till or reduced-till soil management practices. Survival spor...

  5. Grass seedling demography and sage steppe restoration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seeding is a key management tool for semi-arid and arid rangeland. In these systems, however, seeded species often fail to establish. The objectives of this study were to identify demographic transitions limiting seedling recruitment in a disturbed, sage steppe system and determine the degree to w...

  6. Seedling recruitment in forests: Calibrating models to predict patterns of tree seedling dispersion

    SciTech Connect

    Ribbens, E.; Silander, J.A. Jr.; Pacala, S.W. )

    1994-09-01

    Recruitment, the addition of new individuals into a community, is an important factor that can substantially affect community composition and dynamics. We present a method for calibrating spatial models of plant recruitment that does not require identifying the specific parent of each recruitment. This method calibrates seedling recruitment functions by comparing tree seedling distributions with adult distributions via a maximum likelihood analysis. The models obtained from this method can then be used to predict the spatial distributions of seedlings from adult distributions. We calibrated recruitment functions for 10 tree species characteristic of transition oak-northern hardwood forests. Significant differences were found in recruitment abundances and spatial distributions. Predicted seedling recruitment limitation for test stands varied substantially between species, with little recruitment limitation for some species and strong recruitment limitation for others. Recruitment was limited due to low overall recruit production or to restricted recruit dispersion. When these seedling recruitment parameters were incorporated into a spatial, individual-based model of forest dynamics, called SOR-TIE, alterations of recruitment parameters produced substantial changes in species abundance, providing additional support for the potential importance of seedling recruitment processes in community structure and dynamics. 45 refs., 9 figs., 3 tabs.

  7. Lectins in Castor Bean Seedlings 1

    PubMed Central

    Harley, Suzanne M.; Beevers, Harry

    1986-01-01

    The amounts of the two lectins (ricin and Ricinus communis agglutinin) in tissues of castor bean seedlings were followed during germination and early growth. For measurement, lectins in extracts were separately eluted from Sepharose columns; an antibody to the agglutinin was also used to detect the lectins by immunodiffusion. The endosperm of the dry seed contains 3.5 mg total lectin (5.6% of the total seed protein), which declines by 50% by day 4 and more rapidly thereafter as the tissue is completely consumed. The cotyledons of the dry seed also contain lectins but the amounts are less than 1% of those in the endosperm, and, as in the endosperm, they are constituents of the albumin fraction of the isolated protein bodies. No lectins were detected in the green cotyledons of 10-day seedlings that had been exposed to light from day 5. The embryonic axes of 2-day seedlings contained very small amounts of lectins but they were not detectable in the aerial parts of seedlings grown for 3 weeks or in cells from endosperm grown in tissue culture. The ability of proteinases and glycosidases (isolated from endosperm of 4-day seedlings) to hydrolyze the lectins was examined. No hydrolysis of the two lectins was observed, but the subunits, separated by reduction with 2-mercaptoethanol, were hydrolyzed slowly by a proteinase and some release of mannose was observed in the presence of the glycosidases. Ricin was converted to its subunits by cysteine and an enzyme in an endosperm extract accelerated chain separation by glutathione. Images Fig. 3 PMID:16664561

  8. On the biomechanics of seedling anchorage

    NASA Astrophysics Data System (ADS)

    Crouzy, Benoît; Edmaier, Katharina; Perona, Paolo

    2014-05-01

    We propose a minimal model for the response of vegetation to pullout constraints at early development stage. We try to capture both the average mechanical properties of the root system and the stochastic component of the uprooting process of seedlings. We identify a minimal set of relevant physical components in the purpose of quantifying the uprooting process: length of the root fibres, elastic response of the fibres and adhesion between the roots and the soil matrix. We present for validation a dataset extracted from Edmaier et al. (under revision), accounting for 98 uprooting experiments using Avena sativa L. seedlings (common oat), growing in non-cohesive sediment under controlled conditions. The corresponding root system has a very simple architecture, with three root fibres of different lengths. The response of the system to the constraint is however complex: the stress-strain signal presents sudden jumps followed by partial elastic recoveries. The analysis of the jumps and partial recoveries gives an insight into the resilience of the system. The anchorage of less mature seedlings rapidly collapses after the peak force has been reached, while more mature seedlings usually recover from partial failures. We explore this crossover with our validation dataset. The type of seedlings we study has been used in flume experiments investigating the feedbacks between the vegetation and the river morphodynamics (see for example Perona et al. (2012)). An understanding of the characteristics of the uprooting curve (maximal uprooting force and total uprooting work) of such vegetation reveals the ability of seedlings to withstand environmental constraints in terms of duration or intensity (see Edmaier et al., under revision), and is therefore helpful for planning future experiments. REFERENCES - P. Perona, P. Molnar, B. Crouzy, E. Perucca, Z. Jiang, S. McLelland, D. Wüthrich, K. Edmaier, R. Francis, C. Camporeale, et al., Biomass selection by floods and related timescales

  9. Early events in geotropism of seedling shoots

    NASA Technical Reports Server (NTRS)

    Pickard, B. G.

    1985-01-01

    Developments during the first ten minutes of geotropic stimulation in plant seedling shoots are reviewed. Topics include induction and curvature; early processes; the relationship between auxin, electric field, calcium, and differential growth; gravity reception leading to Went-Cholodny transport; and comparison of root and shoot. Early processes reviewed are sedimentation of amyloplasts, release of ethylene, rise of electrical and auxin asymmetry, redistribution of calcium, asymmetric vascular transport, increase in tendency to deposit callose, and simulation of putative exocytotic voltage transients.

  10. TEMPORAL ALLOCATION OF 14C TO EXTRAMATRICAL HYPHAE OF ECTOMYCORRHIZAL PONDEROSA PINE SEEDLINGS

    EPA Science Inventory

    Ponderosa pine seedlings were inoculated with Hebeloma crustuliniforme either in growth pouches before they were transplanted to root-mycocosms (P seedlings), or at the time of transfer to root-mycocosms (V seedlings). ninoculated seedlings served as controls (U seedlings). he us...

  11. Enhancement of American chestnut somatic seedling production.

    PubMed

    Andrade, G M; Merkle, S A

    2005-08-01

    Somatic embryogenesis holds promise for mass propagation of American chestnut trees bred or genetically engineered for resistance to chestnut blight. However, low germination frequency of chestnut somatic embryos has limited somatic seedling production for this forest tree. We tested the effects of culture regime (semi-solid versus liquid), cold treatment, AC and somatic embryo morphology (i.e., cotyledon number) on germination and conversion of the somatic embryos. Cold treatment for 12 weeks was critical for conversion of chestnut somatic embryos to somatic seedlings, raising conversion frequencies for one line to 47%, compared to 7% with no cold treatment. AC improved germination and conversion frequency for one line to 77% and 59%, respectively, and kept roots from darkening. For two lines that produced embryos with one, two or three-plus cotyledons, cotyledon number did not affect germination or conversion frequency. We also established embryogenic American chestnut suspension cultures and adapted a fractionation/plating system that allowed us to produce populations of relatively synchronous somatic embryos for multiple lines. Embryos derived from suspension cultures of two lines tested had higher conversion frequencies (46% and 48%) than those from cultures maintained on semi-solid medium (7% and 30%). The improvements in manipulation of American chestnut embryogenic cultures described in this study have allowed over a 100-fold increase in somatic seedling production efficiency over what we reported previously and thus constitute a substantial advance toward the application of somatic embryogenesis for mass clonal propagation of the tree. PMID:15789206

  12. 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.

  13. Habitat-related variation in seedling recruitment of Gentiana pannonica

    NASA Astrophysics Data System (ADS)

    Ekrtová, Ester; Košnar, Jan

    2012-11-01

    Differences in seedling recruitment of Gentiana pannonica were investigated between the primary (relict) and the secondary (semi-natural) forest-free habitats of the Bohemian Forest (870-1200 m a.s.l.) and of the Alps (1045-1935 m a.s.l.) to understand the factors promoting the seedling recruitment of G. pannonica and their importance for species distribution, population structure, and conservation. In the communities with adult plants of G. pannonica, we recorded environmental variables (the slope, the altitude, and the covers of bare ground, litter, and rocks), estimated parameters of the vegetation (the covers of herbs, bryophytes, and dwarf shrubs), and counted the seedlings of G. pannonica. In a field experiment, we investigated seedling survival under different soil moisture regimes. We also observed seasonal dynamics of seedling recruitment in permanent plots over the course of three years. In the primary habitats of both regions, G. pannonica grew in a relatively wide range of communities, and its seedlings occurred in each area. In the secondary habitats of the Bohemian Forest, a very low frequency of the seedlings was recorded. The number of seedlings increased with the covers of the moss layer and of bare soil and decreased with the cover of the herb layer, especially of graminoids. The seedling mortality was significantly lower in the plots with higher soil moistures, and the emergence of new-born seedlings was concentrated in the spring season, when the soil received a high water supply due to melting of snow. For the successful generative reproduction of G. pannonica, our findings highlight the critical importance of the microsites with low levels of competition and of sufficient soil moisture G. pannonica. It seems that because of the long-term lack of grazing disturbances, the structures of the secondary habitats of G. pannonica in the Bohemian Forest have become unfavourable for seedling establishment and generative reproduction of this threatened

  14. Seedlings Finally Get Their Due: Book Review of Seedling Ecology and Evolution

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Book Review of: Seedling Ecology and Evolution. Ed. Leck, Mary Allessio, Parker, V. Thomas and Simpson, Robert L. Cambridge University Press, Cambridge, UK. 2008. Many plant demographers find themselves, at some point, staring at a dataset full of detailed information on juvenile and adult plants,...

  15. Radiation effects on Brassica seeds and seedlings

    NASA Astrophysics Data System (ADS)

    Deoli, Naresh; Hasenstein, Karl H.

    2016-07-01

    Space radiation consists of high energy charged particles and affects biological systems, but because of its stochastic, non-directional nature is difficult to replicate on Earth. Radiation damages biological systems acutely at high doses or cumulatively at low doses through progressive changes in DNA organization. These damages lead to death or cause of mutations. While radiation biology typically focuses on mammalian or human systems, little is known as to how radiation affects plants. In addition, energetic ion beams are widely used to generate new mutants in plants considering their high-LET (Linear Energy Transfer) as compared to gamma rays and X-rays. Understanding the effect of ionizing radiation on plant provides a basis for studying effects of radiation on biological systems and will help mitigate (space) radiation damage in plants. We exposed dry and imbibed Brassica rapa seeds and seedling roots to proton beams of varying qualities and compared the theoretical penetration range of different energy levels with observable growth response. We used 1, 2 and 3 MeV protons in air at the varying fluences to investigate the effect of direct irradiation on the seeds (1012 - 1015 ions/cm2) and seedlings (1013 ions/cm2). The range of protons in the tissue was calculated using Monte-Carlo based SRIM (Stopping and Range of Ions in Matter) software. The simulation and biological results indicate that ions did not penetrate the tissue of dry or hydrated seeds at all used ion energies. Therefore the entire energy was transferred to the treated tissue. Irradiated seeds were germinated vertically under dim light and roots growth was observed for two days after imbibition. The LD50 of the germination was about 2×1014 ions/cm2 and about 5×1014 ions/cm2 for imbibed and dry seeds, respectively. Since seedlings are most sensitive to gravity, the change in gravitropic behavior is a convenient means to assess radiation damage on physiological responses other than direct tissue

  16. Sand abrasion injury and biomass partitioning in cotton seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind blown soil particle abrasion negatively impacts millions of hectares of crops annually. The goal of this study was to examine the effects of wind and wind blown sand abrasion damage on cotton (Gossypium hirsutum L.) seedling biomass partitioning to leaves, stems, and roots. Seedlings of three ...

  17. Evaluation of Promalin to promote growth of young mangosteen seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A major impediment to the development of a mangosteen (Garcinia mangostana L.) industry is the long pre-bearing stage that seedlings take to produce fruits. A field study was conducted to determine the effect of Promalin on the growth of mangosteen seedlings. Promalin was applied as a foliar spray...

  18. [Experimental studies on growing seedlings of Morinda officinalis How].

    PubMed

    Wei, X; Pang, F; He, M; Hu, T

    1992-10-01

    By using the techniques of growing seedlings in bowshaped shed covered with plastic sheeting plus treatment with plant growth regulator, vegetative and generative propagation tests have been made of Morinda officinalis. Scientific evidences have thus been provided for growing seedlings of Morinda officinalis. PMID:1294174

  19. Seedling diseases of sugar beet – diversity and host interactions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seedling diseases cause loss of plant stand due to pre- and post-emergence damping-off and weakened plants due to root or hypocotyl infection. Several pathogens cause seedling disease of sugar beet, including Rhizoctonia solani, Aphanomyces cochlioides, Pythium species, and Fusarium species. Differe...

  20. Competitive suppression of Quercus douglasii (Fagaceae) seedling emergence and growth.

    PubMed

    Gordon, D R; Rice, K J

    2000-07-01

    Reduced recruitment of blue oak (Quercus douglasii) seedlings in California grasslands and woodlands may result from shifts in seasonal soil water availability coincident with replacement of the native perennial herbaceous community by Mediterranean annuals. We used a combination of container and field experiments to examine the interrelationships between soil water potential, herbaceous neighborhood composition, and blue oak seedling shoot emergence and growth. Neighborhoods of exotic annuals depleted soil moisture more rapidly than neighborhoods of a perennial grass or "no-neighbor" controls. Although effects of neighborhood composition on oak seedling root elongation were not statistically significant, seedling shoot emergence was significantly inhibited in the annual neighborhoods where soil water was rapidly depleted. Seedling water status directly reflected soil water potential, which also determined the extent and duration of oak seedling growth during the first year. End-of-season seedling height significantly influenced survival and growth in subsequent years. While growth and survival of blue oak seedlings may be initially constrained by competition with herbaceous species, subsequent competition with adult blue oak trees may further contribute to reduced sapling recruitment. PMID:10898776

  1. A hydrothermal seedling emergence model for giant ragweed (Ambrosia trifida)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Late-season seedling emergence of giant ragweed in Ohio crop fields complicates efforts for predicting the optimum time to implement control measures for minimizing crop-yield losses. Our objectives were to develop a hydrothermal seedling emergence model for a late-emerging biotype in Ohio and valid...

  2. Examining salt stress for improvement of seedling vigor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Emergence and stand establishment through the first 10 weeks after planting continue to be primary concerns of sugar beet growers worldwide. Our goal is to understand the genes and genetics of seedling vigor, with vigor defined here as the ability of seedlings to tolerate adverse environments. Ongoi...

  3. Seedling emergence of yellow woodsorrel in eastern South Dakota

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yellow woodsorrel is a perennial weed invading no-till rotations in eastern South Dakota. This study quantified the seedling emergence pattern of yellow woodsorrel across a four-year period. Yellow woodsorrel began emerging in early May and continued for 14 weeks. Approximately 80% of seedlings em...

  4. Chilling stress response of post-emergent cotton seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    • Early season development of cotton is often impaired by sudden episodes of chilling temperature. We determined the chilling response specific to post-emergent 13-d-old cotton seedlings. • Seedlings were gradually chilled during the dark period and rewarmed during the night-to-day transition. Fo...

  5. Sand abrasion injury and biomass partitiioning in cotton seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind blown soil particle abrasion negatively impacts millions of hectares of crops annually. The goal of this study was to examine the effects of wind and wind blown sand abrasion damage on cotton (Gossypium hirsutum L.) seedling biomass partitioning to leaves, stems, and roots. Seedlings of three ...

  6. Sand abrasion injury and biomass partitioning in cotton seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of acres of crops are exposed to wind blown sand abrasion injury each year and in many instances the damage is thought to be sufficiently severe to require replanting. The goal of this study was to determine the effects of wind blown sand abrasion duration on cotton seedlings. Seedlings of ...

  7. Evolutionary history and distance dependence control survival of dipterocarp seedlings.

    PubMed

    Bagchi, Robert; Press, Malcolm C; Scholes, Julie D

    2010-01-01

    One important hypothesis to explain tree-species coexistence in tropical forests suggests that increased attack by natural enemies near conspecific trees gives locally rare species a competitive advantage. Host ranges of natural enemies generally encompass several closely related plant taxa suggesting that seedlings should also do poorly around adults of closely related species. We investigated the effects of adult Parashorea malaanonan on seedling survival in a Bornean rain forest. Survival of P. malaanonan seedlings was highest at intermediate distances from parent trees while heterospecific seedlings were unaffected by distance. Leaf herbivores did not drive this relationship. Survival of seedlings was lowest for P. malaanonan, and increased with phylogenetic dissimilarity from this species, suggesting that survival of close relatives of common species is reduced. This study suggests that distance dependence contributes to species coexistence and highlights the need for further investigation into the role of shared plant enemies in community dynamics. PMID:19849708

  8. Enantioselective Phytotoxicity of Imazamox Against Maize Seedlings.

    PubMed

    Wei, Jing; Zhang, Xiaoxiao; Li, Xuesheng; Zeng, Dongqiang; Tan, Huihua

    2016-02-01

    There is increasing concern about the enantioselective effects of chiral herbicides. To study the enantioselective toxicity of the chiral herbicide imazamox on maize, maize seedlings (Zhengda 619, Zea mays L.) were exposed to imazamox racemate and enantiomers in hydroponic experiments. The results showed that imazamox enantiomers selectively affected maize. The effective concentration of Rac-, S- and R-imazamox that caused 50 % inhibition after 5 days treatments (EC50,5d) were 0.4212, 1.2142 and 0.2460 mg L(-1), respectively, for maize root length; 0.0002, 0.1005, 0.0032 mg L(-1), respectively, for maize root fresh weight; 0.7114, 1.4056 and 0.4530 mg L(-1), respectively, for maize shoot height; 0.6220, 1.5418, 0.2286 mg L(-1), respectively, for maize shoot fresh weight; and 0.1100, 0.3306, 0.0307 mg L(-1), respectively, for the total chlorophyll content of leaves. The root morphological parameters and root activity reflected the toxicity effects in the order R-imazamox > Rac-imazamox > S-imazamox. Maize roots were more sensitive to imazamox than maize shoots. The chiral herbicide imazamox poses enantioselective phytotoxicity on maize seedlings: the order of toxicity is R-imazamox > Rac-imazamox > S-imazamox. PMID:26508428

  9. Process-based modeling of temperature and water profiles in the seedling recruitment zone: Part II. Seedling emergence timing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Predictions of seedling emergence timing for spring wheat are facilitated by process-based modeling of the microsite environment in the shallow seedling recruitment zone. Hourly temperature and water profiles within the recruitment zone for 60 days after planting were simulated from the process-base...

  10. 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

  11. Flow and scour constraints on uprooting of pioneer woody seedlings

    NASA Astrophysics Data System (ADS)

    Bywater-Reyes, Sharon; Wilcox, Andrew C.; Stella, John C.; Lightbody, Anne F.

    2015-11-01

    Scour and uprooting during flood events is a major disturbance agent that affects plant mortality rates and subsequent vegetation composition and density, setting the trajectory of physical-biological interactions in rivers. During flood events, riparian plants may be uprooted if they are subjected to hydraulic drag forces greater than their resisting force. We measured the resisting force of woody seedlings established on river bars with in situ lateral pull tests that simulated flood flows with and without substrate scour. We quantified the influence of seedling size, species (Populus and Tamarix), water-table depth, and scour depth on resisting force. Seedling size and resisting force were positively related with scour depth and water-table depth—a proxy for root length—exerting strong and opposing controls on resisting force. Populus required less force to uproot than Tamarix, but displayed a greater increase in uprooting force with seedling size. Further, we found that calculated mean velocities required to uproot seedlings were greater than modeled flood velocities under most conditions. Only when plants were either shallowly rooted or subjected to substrate scour (≥0.3 m) did the calculated velocities required for uprooting decrease to within the range of modeled flood velocities, indicating that drag forces alone are unlikely to uproot seedlings in the absence of extreme events or bar-scale sediment transport. Seedlings on river bars are most resilient to uprooting when they are large, deeply rooted, and unlikely to experience substrate scour, which has implications for ecogeomorphic evolution and river management.

  12. Effects of "short" photoperiods on seedling growth of Pinus brutia.

    PubMed

    Iakovoglou, V; Radoglou, K; Kostopoulou, P; Dini-Papanastasi, O

    2012-03-01

    This study investigated how nurseries could benefit by inducing "short" photoperiods as low as 4 hr to produce "better" seedlings characterized by more vigorous roots; a substantial feature to overcome transplanting stress. The carryover effect of the photoperiod was also investigated on seedlings that grew for 30 days more underthe consistent 14 hr photoperiod. Seedlings of Pinus brutia were subjected to 4, 6, 8 and 14 hr photoperiod for 3 week. Fifteen seedlings were used to evaluate the leaf area, the root and shoot dry weight and their ratio. Six and sixteen seedlings were used to evaluate the shoot electrolyte leakage and the root growth potential, respectively. Based on the results, the 6 and 8 hr photoperiod indicated greater root allocation (4.8 and 4.9 mg, respectively) and chlorophyll content (3.7 and 4.4, respectively). They also indicated greater leaf area values (3.3 and 3.5 cm2, respectively) along with the 14 hr (3.4 cm2). The photoperiod effect continued even after seedlings were subjected at consistent photoperiod. Overall, "short" photoperiods could provide "better" P. brutia seedlings to accommodate immediate massive reforestation and afforestation needs. PMID:23033672

  13. Photomodulation of strigolactone biosynthesis and accumulation during sunflower seedling growth

    PubMed Central

    Bharti, Niharika; Tripathi, Smita; Bhatla, Satish Chander

    2015-01-01

    Present investigations report the presence of strigolactones (SLs) and photomodulation of their biosynthesis in sunflower seedlings (roots, cotyledons and first pair of leaves) during early phase of seedling development. Qualitative analyses and characterization by HPLC, ESI-MS and FT-IR revealed the presence of more than one type of SLs. Orobanchyl acetate was detected both in roots and leaves. Five-deoxystrigol, sorgolactone and orobanchol were exclusively detected in seedling roots. Sorgomol was detectable only in leaves. HPLC eluted fraction from seedling roots and leaves co-chromatographing with GR24 (a synthetic SL) could also bring about germination in Orobanche cernua (a weed) seeds, which are established to exhibit SL – mediated germination, thereby indicating the SL identity of the eluates using this bioassay. SLs accumulation was always more in the roots of light-grown seedlings, it being maximum at 4 d stage. Although significant activity of carotenoid cleavage dioxygenase (CCD, the enzyme critical for SL biosynthesis) was detected in 2 d old seedling roots, SLs remained undetectable in cotyledons at all stages of development and also in the roots of 2 d old light and dark-grown seedlings. Roots of light-grown seedlings showed maximum CCD activity during early (2 d) stage of development, thereby confirming photomodulation of enzyme activity. These observations indicate the migration of a probable light-sensitized signaling molecule (yet to be identified) or a SL precursor from light exposed aerial parts to the seedling roots maintained in dark. Thus, a photomodulation and migration of SL precursor/s is evident from the present work. PMID:26252191

  14. Photomodulation of strigolactone biosynthesis and accumulation during sunflower seedling growth.

    PubMed

    Bharti, Niharika; Tripathi, Smita; Bhatla, Satish Chander

    2015-01-01

    Present investigations report the presence of strigolactones (SLs) and photomodulation of their biosynthesis in sunflower seedlings (roots, cotyledons and first pair of leaves) during early phase of seedling development. Qualitative analyses and characterization by HPLC, ESI-MS and FT-IR revealed the presence of more than one type of SLs. Orobanchyl acetate was detected both in roots and leaves. Five-deoxystrigol, sorgolactone and orobanchol were exclusively detected in seedling roots. Sorgomol was detectable only in leaves. HPLC eluted fraction from seedling roots and leaves co-chromatographing with GR24 (a synthetic SL) could also bring about germination in Orobanche cernua (a weed) seeds, which are established to exhibit SL - mediated germination, thereby indicating the SL identity of the eluates using this bioassay. SLs accumulation was always more in the roots of light-grown seedlings, it being maximum at 4 d stage. Although significant activity of carotenoid cleavage dioxygenase (CCD, the enzyme critical for SL biosynthesis) was detected in 2 d old seedling roots, SLs remained undetectable in cotyledons at all stages of development and also in the roots of 2 d old light and dark-grown seedlings. Roots of light-grown seedlings showed maximum CCD activity during early (2 d) stage of development, thereby confirming photomodulation of enzyme activity. These observations indicate the migration of a probable light-sensitized signaling molecule (yet to be identified) or a SL precursor from light exposed aerial parts to the seedling roots maintained in dark. Thus, a photomodulation and migration of SL precursor/s is evident from the present work. PMID:26252191

  15. Growth of ponderosa pine seedlings as affected by air pollution

    NASA Astrophysics Data System (ADS)

    Momen, B.; Anderson, P. D.; Houpis, J. L. J.; Helms, J. A.

    The effect of air pollution on seedling survival and competitive ability is important to natural and artificial regeneration of forest trees. Although biochemical and physiological processes are sensitive indicators of pollution stress, the cumulative effects of air pollutants on seedling vigor and competitive ability may be assessed directly from whole-plant growth characteristics such as diameter, height, and photosynthetic area. A few studies that have examined intraspecific variation in seedling response to air pollution indicate that genotypic differences are important in assessing potential effects of air pollution on forest regeneration. Here, we studied the effects of acid rain (no-rain, pH 5.1 rain, pH 3.0 rain) and ozone (filtered, ambient, twice-ambient) in the field on height, diameter, volume, the height:diameter ratio, maximum needle length, and time to reach maximum needle length in seedlings of three families of ponderosa pine ( Pinus ponderosa Dougl. ex Laws). Seedling diameter, height, volume, and height:diameter ratio related significantly to their pre-treatment values. Twice-ambient ozone decreased seedling diameter compared with ozone-filtered air. A significant family-by-ozone interaction was detected for seedling height, as the height of only one of the three families was decreased by twice-ambient ozone compared with the ambient level. Seedling diameter was larger and the height:diameter ratio was smaller under pH 3.0 rain compared to either the no-rain or the pH 5.1-rain treatment. This suggests greater seedling vigor, perhaps due to a foliar fertilization effect of the pH 3.0 rain.

  16. BIM LAU-PE: Seedlings in Microgravity

    NASA Astrophysics Data System (ADS)

    Gass, S.; Pennese, R.; Chapuis, D.; Dainesi, P.; Nebuloni, S.; Garcia, M.; Oriol, A.

    2015-09-01

    The effect of gravity on plant roots is an intensive subject of research. Sounding rockets represent a costeffective platform to study this effect under microgravity conditions. As part of the upcoming MASER 13 sounding rocket campaign, two experiments on Arabidopsis thaliana seedlings have been devised: GRAMAT and SPARC. These experiments are aimed at studying (1) the genes that are specifically switched on or off during microgravity, and (2) the position of auxin-transporting proteins during microgravity. To perform these experiments, RUAG Space Switzerland site of Nyon, in collaboration with the Swedish Space Corporation (SSC) and the University of Freiburg, has developed the BIM LAU-PE (Biolology In Microgravity Late Access Unit Plant Experiment). In the following an overview of the BIM LAU-PE design is presented, highlighting specific module design features and verifications performed. A particular emphasis is placed on the parabolic flight experiments, including results of the micro-g injection system validation.

  17. Arborescent palm seed morphology and seedling distribution.

    PubMed

    Salm, Rodolfo

    2005-11-01

    This study examines how the seed morphology of two large arborescent palms, Attalea maripa (Aubl.) Mart. and Astrocaryum aculeatum G. Mey, may affect their seed shadow in a seasonally dry Amazonian forest. In addition to being smaller and produced in larger numbers than those of A. aculeatum, A. maripa seeds also presented a substantially lower amount of nutritional reserves available for the embryo. However, A. maripa seedlings were found in much higher numbers than those of A. aculeatum. The results suggest that, within the spatial scale considered, the seed rain of A. maripa is more restricted to the area surrounding around reproductive conspecifics than that of A. aculeatum. Furthermore, in comparison with those of A. aculeatum, the smaller seeds of A. maripa might be less attractive to scatterhoarding rodents (e.g. Dasyprocta aguti). The pattern observed emphasizes the importance of scatterhoarding rodents as dispersers of large-seeded plant species in Neotropical forests. PMID:16532195

  18. Substrate influences ecophysiological performance of tree seedlings.

    PubMed

    Pröll, Gisela; Hietz, Peter; Delaney, Christina M; Katzensteiner, Klaus

    2016-01-01

    Unfavourable soil conditions frequently limit tree regeneration in mountain forests on calcareous bedrock. Rocky, shallow organic soils on dolomite pose a particular problem for tree regeneration due to commonly restricted water and nutrient supplies. Moreover, an often dense layer of understorey vegetation competes for the limited resources available. Hence, an array of interacting factors impairs tree seedlings' performance on dolomite, but there is little information on the ecophysiological mechanisms. We studied the effects of substrate, competing vegetation and foliar nutrient concentrations on the photosynthetic rate (A), stomatal conductance (gs) and leaf water potentials (ψ) of sycamore (Acer pseudoplatanus L.), beech (Fagus sylvatica L.), spruce [Picea abies (L.) Karst.] and larch (Larix decidua Mill.) under controlled (well-watered/drought-stressed) conditions and under prevailing field conditions. While A and gs of well-watered spruce in the pot experiment were reduced by the mineral substrate, the organic dolomite substrate with dense competing vegetation reduced gs and ψ of sycamore, spruce and larch under drought-stressed conditions in the field. For sycamore and spruce, A and gs were strongly correlated with foliar nitrogen (N) and potassium (K) concentrations in the pot experiment. In contrast, soil water primarily affected beech and larch. Finally, dense competing vegetation negatively affected A and gs of spruce and A of larch on dolomite. Our results highlight the critical role of N, K and water availability for tree seedlings in shallow soils on calcareous bedrock. On these sites, natural tree regeneration is at particular risk from episodic drought, a likely consequence of climate change. PMID:26446268

  19. Identification of chromosome regions associated with seedling vigor in rice.

    PubMed

    Huang, Zheng; Yu, Ting; Su, Li; Yu, Si-Bin; Zhang, Zhi-Hong; Zhu, Ying-Guo

    2004-06-01

    Seedling vigor is important for optimum stand establishment in rice cropping. In this paper,a set of 264 F12 recombinant inbred lines (RILs) derived by single seed descent from a cross between Lemont (japonica) and Teqing (indica) was phenotyped for three seedling vigor related traits, including seed germination rate (GR), seedling shoot length and dry weight by the rolled paper towel tests. The phenotype data and a linkage map consisting of 198 DNA markers were combined to map quantitative trait loci (QTL) for seedling vigor by using a computer program QTLMapper1.0. A total of 13 putative main-effect QTL were detected. All of these QTL had much smaller effects on the traits with a mean R2 of 6.2%, ranging from 2.9% to 12.7%. As for digenic interaction, 18 pairs of epistatic loci with R2 > or = 5% were resolved with a mean R2 of 6.9% ,ranging from 5.1% to 11.8%, which was slightly larger than that of the main-effect QTL identified for the traits. The majority of the main-effect and epistatic loci detected for seedling vigor related traits were clustered in a few chromosome regions. Together, seven such chromosome regions (CRs), each with three or more seedling vigor main-effect and epistatic loci, were found to be highly associated with seedling vigor. These CRs can be classified into three types, i.e. M-CRs, E-CRs and ME-CRs. For some CRs just like CR(SV-6), the QTL within one CR were found to interact simultaneously with QTL within more than one other CRs to affect different seedling vigor related traits. The above results revealed that seedling vigor in rice is controlled by many loci, most of which have relatively small effects. Comparatively, epistasis as a genetic factor would be more important than main-effects of QTL for seedling vigor in rice. Nevertheless, the effects of the QTL are still large enough to be detected and in fact several chromosome regions were found to be highly associated with seedling vigor in very different populations as compared with

  20. A leaf phosphorus assay for seedlings of Acacia mangium.

    PubMed

    Sun, J S; Simpson, R J; Sands, R

    1992-10-01

    Concentrations of extractable and total phosphorus in leaves, stem, root and nodules of 12-week-old seedlings of two provenances of Acacia mangium Willd. were analyzed to identify the fraction of phosphorus and the plant part most suitable for predicting the phosphorus nutritional status of the seedlings.For both provenances, concentrations of extractable phosphorus were more sensitive to changes in soil phosphorus status and varied less among different plant parts than concentrations of total phosphorus. Concentrations of extractable phosphorus in the youngest fully expanded leaf (Leaf 3 from the apex) and the next two older leaves correlated closely with seedling dry mass and may be used to assess the phosphorus nutritional status of Acacia mangium seedlings. PMID:14969954

  1. ARC EMCS Experiments (Seedling Growth-2) Experiment Status

    NASA Technical Reports Server (NTRS)

    Heathcote, David; Steele, Marianne

    2015-01-01

    Presentation of the status of the ARC ISS (International Space Station) Experiment, Seedling Growth-2 to the Payload Operations Investigator Working Group meeting at MSFC, Huntsville AL. The experiment employs the European Modular Cultivation System (ECMS).

  2. [Development strategies on seed seedling of Chinese medicinal materials].

    PubMed

    Li, Longyun; Peng, Rui; Li, Hongli; Wu, Yekuan; Cui, Guanglin

    2010-01-01

    This paper analyzed the development status, industrialization system, standardization system and new variety breeding of seed and seedling of Chinese medicinal materials. Based on the development status and problems facing to the seed and seedling industry in China, some reasonable countermeasures are proposed in this article. The main measures include strengthening new variety breeding, establishing experiment site, protecting new variety and standardizing the market and quality management. PMID:20394305

  3. Actin of Beta vulgaris seedlings under the clinorotation

    NASA Astrophysics Data System (ADS)

    Kozeko, L. Ye.

    We study the influence of altered gravity on actin expression in roots of Beta vulguris seedlings grown on the horizontal clinostat (2 rpm) from seed germination for three days. It is shown that the total actin quantity was not influenced. Three actin isoforms are revealed; a relative protein quantity of these isoforms was similar both in clinorotated seedlings and in ones grown in norm. This point to stable expression of actin under the altered gravity conditions.

  4. Eucalyptus obliqua seedling growth in organic vs. mineral soil horizons

    PubMed Central

    Barry, Karen M.; Janos, David P.; Nichols, Scott; Bowman, David M. J. S.

    2015-01-01

    Eucalyptus obliqua, the most widespread timber tree in Tasmania, is a pioneer after fire which can eliminate the organic layer of forest soil, exposing the underlying mineral soil. We compared seedling growth, mycorrhiza formation, and mineral nutrient limitation in organic layer vs. mineral soil. We grew E. obliqua seedlings separately in pots of organic layer and mineral soil in a glasshouse. Additional treatments of organic soil only, involved fully crossed methyl-bromide fumigation and fertilization. Fertilization comprised chelated iron for 121 days after transplant (DAT) followed by soluble phosphorus. At 357 DAT, whole plant dry weight was three times greater in ambient organic than in mineral soil. In organic soil, fumigation halved ectomycorrhiza abundance and reduced seedling growth at 149 DAT, but by 357 DAT when negative effects of fumigation on seedling growth had disappeared, neither fumigation nor fertilization affected mycorrhiza abundance. Iron fertilization diminished seedling growth, but subsequent phosphorus fertilization improved it. E. obliqua seedlings grow much better in organic layer soil than in mineral soil, although phosphorus remains limiting. The prevalent forestry practice of burning to mineral soil after timber harvest exposes a poor growth medium likely only partially compensated by fire-induced mineral soil alterations. PMID:25750650

  5. Eucalyptus obliqua seedling growth in organic vs. mineral soil horizons.

    PubMed

    Barry, Karen M; Janos, David P; Nichols, Scott; Bowman, David M J S

    2015-01-01

    Eucalyptus obliqua, the most widespread timber tree in Tasmania, is a pioneer after fire which can eliminate the organic layer of forest soil, exposing the underlying mineral soil. We compared seedling growth, mycorrhiza formation, and mineral nutrient limitation in organic layer vs. mineral soil. We grew E. obliqua seedlings separately in pots of organic layer and mineral soil in a glasshouse. Additional treatments of organic soil only, involved fully crossed methyl-bromide fumigation and fertilization. Fertilization comprised chelated iron for 121 days after transplant (DAT) followed by soluble phosphorus. At 357 DAT, whole plant dry weight was three times greater in ambient organic than in mineral soil. In organic soil, fumigation halved ectomycorrhiza abundance and reduced seedling growth at 149 DAT, but by 357 DAT when negative effects of fumigation on seedling growth had disappeared, neither fumigation nor fertilization affected mycorrhiza abundance. Iron fertilization diminished seedling growth, but subsequent phosphorus fertilization improved it. E. obliqua seedlings grow much better in organic layer soil than in mineral soil, although phosphorus remains limiting. The prevalent forestry practice of burning to mineral soil after timber harvest exposes a poor growth medium likely only partially compensated by fire-induced mineral soil alterations. PMID:25750650

  6. Molecular biology of Ganoderma pathogenicity and diagnosis in coconut seedlings.

    PubMed

    Kandan, A; Radjacommare, R; Ramanathan, A; Raguchander, T; Balasubramanian, P; Samiyappan, R

    2009-01-01

    The pathogenicity of Ganoderma boninense was tested on coconut seedlings under greenhouse conditions and infection confirmed by using immunological and molecular diagnostic tools. Desiccation of older leaves and the emergence of sporophores were observed from pathogen-inoculated seedlings, whereas a control seedling does not show any pathogenic symptoms. Mature sporophores were formed within 10-13 weeks after inoculation. Polyclonal antibodies raised against mycelial proteins of Ganoderma were used for detection of Ganoderma in infected field palm and seedlings through indirect enzyme-linked immunosorbent assay technique. We adopted dot-immunobinding assay for the detection of Ganoderma from greenhouse and field samples. Under nucleic-acid-based diagnosis, G. boninense (167 bp) was detected from artificially inoculated seedlings and infected field palms by polymerase chain reaction. Apart from these, histopathological studies also support the Ganoderma pathogenicity in coconut seedlings. The pathogenicity test and combination of all the three diagnostic methods for Ganoderma could be highly reliable, rapid, sensitive and effective screening of resistance in planting material in the future. PMID:19418253

  7. Lignification in young plant seedlings grown on earth and aboard the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Cowles, Joe R.; Lemay, R.; Jahns, G.; Scheld, W. H.; Peterson, C.

    1989-01-01

    The Space Shuttle era has provided an opportunity for investigators to conduct experiments in a microgravity environment. Two Shuttle flights, STS-3 and STS-51F, each contained an experiment designed principally to determine whether young plant seedlings exposed to microgravity had reduced lignin content in comparison to seedlings grown at one gravity. Three different plant species, pine, oats, and mung beans, were exposed for eight days to the microgravity environment of the Shuttle. The lignin content of in-flight seedlings was less than the control seedlings in all seven sets of seedlings included in these two experiments. In five sets of seedlings, the reduction in lignin content in flight seedlings ranged from 6 to 24 percent and was statistically significant. In addition, the activity of two enzymes involved in lignin synthesis, phenylalanine ammonia lyase and peroxidase, were significantly reduced in pine seedlings. It was therefore concluded that microgravity, as perceived by young plant seedlings, results in reduced lignin synthesis.

  8. The Vibration Ring. Phase 1; [Seedling Fund

    NASA Technical Reports Server (NTRS)

    Asnani, Vivake M.; Krantz, Timothy L.; Delap, Damon C.; Stringer, David B.

    2014-01-01

    The vibration ring was conceived as a driveline damping device to prevent structure-borne noise in machines. It has the appearance of a metal ring, and can be installed between any two driveline components like an ordinary mechanical spacer. Damping is achieved using a ring-shaped piezoelectric stack that is poled in the axial direction and connected to an electrical shunt circuit. Surrounding the stack is a metal structure, called the compression cage, which squeezes the stack along its poled axis when excited by radial driveline forces. The stack in turn generates electrical energy, which is either dissipated or harvested using the shunt circuit. Removing energy from the system creates a net damping effect. The vibration ring is much stiffer than traditional damping devices, which allows it to be used in a driveline without disrupting normal operation. In phase 1 of this NASA Seedling Fund project, a combination of design and analysis was used to examine the feasibility of this concept. Several designs were evaluated using solid modeling, finite element analysis, and by creating prototype hardware. Then an analytical model representing the coupled electromechanical response was formulated in closed form. The model was exercised parametrically to examine the stiffness and loss factor spectra of the vibration ring, as well as simulate its damping effect in the context of a simplified driveline model. The results of this work showed that this is a viable mechanism for driveline damping, and provided several lessons for continued development.

  9. Amino acids in seeds and seedlings of the genus Lens.

    PubMed

    Rozan, P; Kuo, Y H; Lambein, F

    2001-09-01

    The amino acid content of seeds and 4-day-old seedlings were studied in five species of lentil: Lens culinaris, L. orientalis, L. ervoides, L. nigricans and L. odemensis. Free amino acid and also total protein amino acid content after HCl hydrolysis were determined by HPLC. The nonprotein UV-absorbing amino acids were determined by capillary zone electrophoresis (CZE). The content of free protein amino acids in seeds varied among species and increased dramatically after germination. Asparagine is quantitatively most important in both seed and seedling. The content of free nonprotein amino acids is variable in seeds and seedlings. gamma-Hydroxyarginine, gamma-hydroxyornithine, alpha-aminobutyric acid and taurine were found in both seeds and seedlings. Homoarginine was found in four species but not in L. orientalis while gamma-aminobutyric acid (GABA), alpha-aminoadipic acid (alpha-aaa) and three isoxazolinone derivatives: beta-(isoxazolin-5-on-2-yl)-alanine (BIA), gamma-glutamyl-BIA (gamma-glu-BIA) and 2-carboxymethyl-isoxazolin-5-one (CMI) were found exclusively in the seedlings. CMI was identified for the first time in lentil species. Lathyrine, beta-(2-amino-pyrimidine-4-yl)-alanine, which was reported to be in the seeds of some Lathyrus species was confirmed to be present also in the seedling of L. culinaris (trace amount), L. nigricans and L. odemensis. Trigonelline (N-methyl-nicotinic acid), a plant hormone, is present both in seeds and seedlings in different concentrations except in L. ervoides. The different combination of nonprotein amino acids among the species gives indication of their genetic relationship and might partly explain the varying compatibility for interspecies crossing. PMID:11551552

  10. Forest tree seedlings may suffer from predicted future winters

    NASA Astrophysics Data System (ADS)

    Domisch, Timo; Repo, Tapani; Martz, Françoise; Rautio, Pasi

    2016-04-01

    Future climate scenarios predict increased precipitation and air temperatures, particularly at high latitudes, and especially so during winter, spring and autumn. However, soil temperatures are more difficult to predict, since they depend strongly on the insulating snow cover. Warm periods during winter can lead to thaw-freeze cycles and flooding, which again can result in the formation of ice layers, affecting soil properties, soil gas concentrations and the survival of tree seedlings. We conducted two laboratory experiments of 20 weeks duration each, simulating winter, spring and early summer, and imposed Scots pine (Pinus sylvestris L.) or downy birch (Betula pubescens Ehrh.) seedlings to four different winter scenarios: (1) ambient snow cover, (2) compressed snow and ice encasement, (3) frozen flood and (4) no snow. We estimated the stress that the seedlings experienced by means of gas exchange, chlorophyll fluorescence and determining above- and belowground biomass and carbohydrate contents, as well as measuring soil oxygen and carbon dioxide concentrations. The seedlings in the snow and compressed snow treatments survived until the end of the experiments, although only those covered with an ambient snow cover showed normal height growth and typical carbohydrate contents. The seedlings in the other treatments showed symptoms of dieback already during early spring and had almost completely died at the end of the experiment. Our results suggest the crucial significance of the protective snow cover, and that a missing soil cover or soil hypoxia and anoxia during winter can be lethal for seedlings, and that respiratory losses and winter desiccation of aboveground organs can further lead to the death of tree seedlings.

  11. Gene Expression in Plant Lipid Metabolism in Arabidopsis Seedlings

    PubMed Central

    Hsiao, An-Shan; Haslam, Richard P.; Michaelson, Louise V.; Liao, Pan; Napier, Johnathan A.; Chye, Mee-Len

    2014-01-01

    Events in plant lipid metabolism are important during seedling establishment. As it has not been experimentally verified whether lipid metabolism in 2- and 5-day-old Arabidopsis thaliana seedlings is diurnally-controlled, quantitative real-time PCR analysis was used to investigate the expression of target genes in acyl-lipid transfer, β-oxidation and triacylglycerol (TAG) synthesis and hydrolysis in wild-type Arabidopsis WS and Col-0. In both WS and Col-0, ACYL-COA-BINDING PROTEIN3 (ACBP3), DIACYLGLYCEROL ACYLTRANSFERASE1 (DGAT1) and DGAT3 showed diurnal control in 2- and 5-day-old seedlings. Also, COMATOSE (CTS) was diurnally regulated in 2-day-old seedlings and LONG-CHAIN ACYL-COA SYNTHETASE6 (LACS6) in 5-day-old seedlings in both WS and Col-0. Subsequently, the effect of CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY) from the core clock system was examined using the cca1lhy mutant and CCA1-overexpressing (CCA1-OX) lines versus wild-type WS and Col-0, respectively. Results revealed differential gene expression in lipid metabolism between 2- and 5-day-old mutant and wild-type WS seedlings, as well as between CCA1-OX and wild-type Col-0. Of the ACBPs, ACBP3 displayed the most significant changes between cca1lhy and WS and between CCA1-OX and Col-0, consistent with previous reports that ACBP3 is greatly affected by light/dark cycling. Evidence of oil body retention in 4- and 5-day-old seedlings of the cca1lhy mutant in comparison to WS indicated the effect of cca1lhy on storage lipid reserve mobilization. Lipid profiling revealed differences in primary lipid metabolism, namely in TAG, fatty acid methyl ester and acyl-CoA contents amongst cca1lhy, CCA1-OX, and wild-type seedlings. Taken together, this study demonstrates that lipid metabolism is subject to diurnal regulation in the early stages of seedling development in Arabidopsis. PMID:25264899

  12. Assessing Posidonia oceanica Seedling Substrate Preference: An Experimental Determination of Seedling Anchorage Success in Rocky vs. Sandy Substrates

    PubMed Central

    Alagna, Adriana; Fernández, Tomás Vega; Anna, Giovanni D; Magliola, Carlo; Mazzola, Salvatore; Badalamenti, Fabio

    2015-01-01

    In the last decades the growing awareness of the ecological importance of seagrass meadows has prompted increasing efforts to protect existing beds and restore degraded habitats. An in-depth knowledge of factors acting as major drivers of propagule settlement and recruitment is required in order to understand patterns of seagrass colonization and recovery and to inform appropriate management and conservation strategies. In this work Posidonia oceanica seedlings were reared for five months in a land-based culture facility under simulated natural hydrodynamic conditions to identify suitable substrates for seedling anchorage. Two main substrate features were investigated: firmness (i.e., sand vs. rock) and complexity (i.e., size of interstitial spaces between rocks). Seedlings were successfully grown in culture tanks, obtaining overall seedling survival of 93%. Anchorage was strongly influenced by substrate firmness and took place only on rocks, where it was as high as 89%. Anchorage occurred through adhesion by sticky root hairs. The minimum force required to dislodge plantlets attached to rocky substrates reached 23.830 N (equivalent to 2.43 kg), which would potentially allow many plantlets to overcome winter storms in the field. The ability of rocky substrates to retain seedlings increased with their complexity. The interstitial spaces between rocks provided appropriate microsites for seedling settlement, as seeds were successfully retained, and a suitable substrate for anchorage was available. In conclusion P. oceanica juveniles showed a clear-cut preference for hard substrates over the sandy one, due to the root system adhesive properties. In particular, firm and complex substrates allowed for propagule early and strong anchorage, enhancing persistence and establishment probabilities. Seedling substrate preference documented here leads to expect a more successful sexual recruitment on hard bottoms compared with soft ones. This feature could have influenced P

  13. Rhizotoxic effects of silver in cowpea seedlings.

    PubMed

    Blamey, F Pax C; Kopittke, Peter M; Wehr, J Bernhard; Kinraide, Thomas B; Menzies, Neal W

    2010-09-01

    Silver (Ag) is highly toxic to aquatic organisms, including algae, invertebrate animals, and fish, but little information exists on Ag rhizotoxicity in higher plants. In two solution culture experiments with approximately 1,000 microM Ca(NO3)2 and 5 microM H3BO3 (pH 5.4), 20 to 80% of added Ag (< or =2 microM) was lost from solution within approximately 30 min, with a further decrease after 48 h root growth. Using measured Ag concentrations at the start of the experiments, the median effective concentration (EC50) for root elongation rate of cowpea (Vigna unguiculata [L.] Walp. cv. Caloona) was 0.010 microM Ag in the first 4 h of exposure (0.021 microM in the first 8 h). This demonstrates that Ag (as Ag+) is rapidly rhizotoxic to cowpea seedlings at concentrations similar to those that are toxic to freshwater biota. Rupturing of rhizodermal and outer cortical layers was evident after 48 h with 0.13 to 0.57 microM Ag initially in solution, being most severe at 0.13 or 0.25 microM Ag. An additional experiment showed that ruptures were first evident after 20 h exposure to 0.17 microM Ag, with increased severity of rupturing over time. The rhizotoxic effects of Ag are similar to those of some other trace metals (e.g., Cu, Al, La) that bind strongly to hard ligands and weakly to soft ligands. The similarity of rupturing effects, despite the difference in strong binding to soft ligands by Ag and to hard ligands by the other metals, suggests a distinctive metabolic effect of Ag that binds only weakly to hard ligands. PMID:20821665

  14. Degraded dryland rehabilitation: boosting seedling survival using zeolitic tuff

    NASA Astrophysics Data System (ADS)

    Alhamad, Mohammad Noor; Alrbabah, Mohammad; Athamneh, Hana

    2016-04-01

    More than 90% of Jordan is broadly defined as rangelands. Most rangelands are located within the arid zone of the country. Extensive grazing occurs across much of the natural pastures resulting in serious environmental degradation of natural resources in these rangelands. Several programs were carried out for rangeland conservation and rehabilitation in the country. However, these programs face a major challenge of the low survival rate of transplanted shrub seedlings. Seeking innovative approaches to assure healthy establishment of seedling is a big challenge to achieve successful rehabilitation programs. Drought is considered one of the major problems in rehabilitation. Promoting survival and growth, using zeolitic tuff added to planting holes is suggested to be a possible solution. The experiment was conducted on a factorial arrangement within RCBD design. Two shrub species (Atriplex halimus, Atriplex nummularia) were transplanted into holes prepared with three levels of tuff treatments (mulching, mixing and control) under rainfed condition. The result showed insignificant effect of tuff on seedling survival percentage, when mixing tuff with plantation soil or adding tuff as mulch. Also, the two species showed similar survival percentages over two measured dates. However, mixing tuff with soil during hole preparation significantly enhanced seedling heights. Furthers, The Australian atriplex (Atriplex nummularia) species significantly grow higher than Atriplex halimus. The study results suggested that mixing zeoltic tuff with soil during transplantation of seedling is promising in improving the success of rangeland rehabilitation in dry areas in Jordan.

  15. Seedling mortality from litterfall increases with decreasing latitude.

    PubMed

    Gillman, Len N

    2016-02-01

    Global patterns in ecology need to be identified and interpreted if macroecological processes are to be fully understood. Facilitating effects on seedlings such as that of nurse plants and competitive effects such as allelopathy have been well recognized but the importance of plants acting as killers through physical damage by the litterfall they produce has received relatively little attention. Here I examine latitudinal patterns of physical disturbance to seedlings (microdisturbance) due to litterfall and discuss the macroecological implications in light of current research. Analyses of results from published studies show that both the risk of litterfall disturbance, as measured using artificial model seedlings, and the proportion of seedling mortalities due to litterfall decrease significantly with increasing latitude. Patterns of microdisturbance appear to be driven by the dynamic interaction between macro-litterfall, safe sites with protective overhead vegetation, topography, and animal activity. However, we are informed on this subject by few studies. There is evidence, again from a limited number of studies, for considerable spatial heterogeneity in microdisturbance intensity and for seedling resilience to litterfall damage to differ substantially among species. Therefore, differential survival among microsites may produce regeneration niche diversity. However, more focused studies are required across a range of forest types and latitudes before these results can be generalized. Therefore, there is fertile ground for researchers to use comparable multifactorial methods to investigate the implications of microdisturbance at macro-ecological scales. PMID:27145626

  16. Why are there few seedlings beneath the myrmecophyte Triplaris americana?

    NASA Astrophysics Data System (ADS)

    Larrea-Alcázar, Daniel M.; Simonetti, Javier A.

    2007-07-01

    We compared the relative importance of chemical alellopathy, pruning behaviour of resident ants and other non-related agents to ant-plant mutualism for seedling establishment beneath Triplaris americana L. (Polygonaceae), a myrmecophyte plant. We also included a preliminary analysis of effects of fragmentation on these ecological processes. Seeds and seedlings of Theobroma cacao L. (Sterculiaceae) were used as the target species in all experiments. Leaf-tissue extracts of the myrmecophyte plant did not inhibit germination of cacao seeds. Resident Pseudomyrmex triplarinus Weddell (Pseudomyrmecinae) ants did not remove seeds under the canopy of their host plants. The main seed consumer was the leaf-cutting ant Atta sexdens L. (Myrmicinae). Leaves of cacao seedlings were partially or totally pruned by Pseudomyrmex ants mainly in forest fragments studied. We offer evidence pointing to the possibility that the absence of seedlings beneath Triplaris may result from effects of both ant species. We discuss the benefits of pruning behaviour for the resident ant colony and the effects of ant-ant interactions on seedling establishment beneath this ant-plant system.

  17. Effect of sorghum seedlings and previous crop, on soil fluorescent pseudomonas spp.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aims: The hypotheses that sorghum seedlings [Sorghum bicolor (L.) Moench] varying in sorgoleone production will differentially modify soil microorganisms and will effect subsequent planting of wheat (Triticum aestivum L.) seedlings were tested. Methods: Wheat cultivar Lewjain, and sorghum genotypes ...

  18. Seedling Interference and Niche Differentiation Between Crested Wheatgrass and Contrasting Native Great Basin Species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Interference from crested wheatgrass (Agropyron cristatum [L.} Gaertn.) seedlings is considered a major obstacle to native species establishment; however, estimates of interference at variable seedling densities have not been fully defined. We conducted greenhouse experiments using an addition seri...

  19. Active Ground Optical Remote Sensing for Improved Monitoring of Seedling Stress in Nurseries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Active ground optical remote sensing (AGORS) devices mounted on overhead irrigation booms could help to improve seedling quality by autonomously monitoring seedling stress. In contrast to traditionally used passive optical sensors, AGORS devices operate independently of ambient light conditions and ...

  20. Effects of Simulated Microgravity on Thermotolerance of Pea Seedlings

    NASA Astrophysics Data System (ADS)

    Kozeko, L.

    2008-06-01

    A coordinated plant response to simulated microgravity (clinorotation) and heat stress was analyzed. 5-d pea seedlings grown on a horizontal clinostat or in the stationary conditions were exposed to different heat treatments (mild, severe and severe after pretreatment). Temperature-dependent quantitative changes in the heat stress response were revealed in the clinorotated seedlings comparatively to the stationary grown ones: less growth activity, an increase in the production of high levels of heat shock proteins Hsp70 and Hsp90, a higher extent of the membrane damage. Thus, clinorotated seedlings were more sensitive to heat stress. The data suggest that clinorotation may influence distinct functions, including Hsps synthesis and protection of membrane integrity, that affect plant growth activity and thermotolerance as a result.

  1. Nitrogen ion utilization by tulip poplar (Liriodendron tulipifera L. ) seedlings

    SciTech Connect

    Mann, L.K.

    1982-01-01

    Growth responses of one-year-old tulip poplar seedlings were determined for different nitrogen sources (HN/sub 4/NO/sub 3/, NH+/sub 4/, NO-/sub 3/, no nitrogen) at 336 ppm N in nutrient culture. At the end of three months, there were no significant differences in growth observed among treatments in terms of stem elongation, leaf area, and leaf size. After four months, however, seedlings of the NH/sub 4/NO/sub 3/ treatment exhibited significantly (P<0.05) greater growth (final weight gain and stem elongation) than all other nitrogen sorces. Growth was slightly less for the NO-/sub 3/ treatment plants, but compared with NH+/sub 4/ and no nitrogen treatment, both NH/sub 4/NO/sub 3/ and NO-/sub 3/ treatments exhibited significantly greater growth responses. NO-/sub 3/ is recommended as the sole nitrogen source, especially for small seedlings of tulip poplar.

  2. Endophytic fungi reduce leaf-cutting ant damage to seedlings

    PubMed Central

    Bittleston, L. S.; Brockmann, F.; Wcislo, W.; Van Bael, S. A.

    2011-01-01

    Our study examines how the mutualism between Atta colombica leaf-cutting ants and their cultivated fungus is influenced by the presence of diverse foliar endophytic fungi (endophytes) at high densities in tropical leaf tissues. We conducted laboratory choice trials in which ant colonies chose between Cordia alliodora seedlings with high (Ehigh) or low (Elow) densities of endophytes. The Ehigh seedlings contained 5.5 times higher endophyte content and a greater diversity of fungal morphospecies than the Elow treatment, and endophyte content was not correlated with leaf toughness or thickness. Leaf-cutting ants cut over 2.5 times the leaf area from Elow relative to Ehigh seedlings and had a tendency to recruit more ants to Elow plants. Our findings suggest that leaf-cutting ants may incur costs from cutting and processing leaves with high endophyte loads, which could impact Neotropical forests by causing variable damage rates within plant communities. PMID:20610420

  3. Endophytic Chaetomium globosum enhances maize seedling copper stress tolerance.

    PubMed

    Abou Alhamed, M F; Shebany, Y M

    2012-09-01

    This study aims at characterisation of the impact of Chaetomium globosum on copper stress resistance of maize seedlings. Higher levels of copper treatment decreased maize dry weight and induced a marked increase in osmotic solutes, antioxidant enzyme activity and the level of lipid peroxidation. On the other hand, addition of the endophytic C. globosum alleviated the toxic effect of copper on maize growth. The combination of copper sulphate and Chaetomium increased seedling dry weight, osmotic solute content and antioxidant enzyme activity compared to copper sulphate alone, while lipid peroxidation levels were also decreased. The fungal scavenger system might be important for supporting the ability of maize seedlings to resist copper toxicity. PMID:22672065

  4. Machine vision system for measuring conifer seedling morphology

    NASA Astrophysics Data System (ADS)

    Rigney, Michael P.; Kranzler, Glenn A.

    1995-01-01

    A PC-based machine vision system providing rapid measurement of bare-root tree seedling morphological features has been designed. The system uses backlighting and a 2048-pixel line- scan camera to acquire images with transverse resolutions as high as 0.05 mm for precise measurement of stem diameter. Individual seedlings are manually loaded on a conveyor belt and inspected by the vision system in less than 0.25 seconds. Designed for quality control and morphological data acquisition by nursery personnel, the system provides a user-friendly, menu-driven graphical interface. The system automatically locates the seedling root collar and measures stem diameter, shoot height, sturdiness ratio, root mass length, projected shoot and root area, shoot-root area ratio, and percent fine roots. Sample statistics are computed for each measured feature. Measurements for each seedling may be stored for later analysis. Feature measurements may be compared with multi-class quality criteria to determine sample quality or to perform multi-class sorting. Statistical summary and classification reports may be printed to facilitate the communication of quality concerns with grading personnel. Tests were conducted at a commercial forest nursery to evaluate measurement precision. Four quality control personnel measured root collar diameter, stem height, and root mass length on each of 200 conifer seedlings. The same seedlings were inspected four times by the machine vision system. Machine stem diameter measurement precision was four times greater than that of manual measurements. Machine and manual measurements had comparable precision for shoot height and root mass length.

  5. Germination and seedling establishment in orchids: a complex of requirements

    PubMed Central

    Rasmussen, Hanne N.; Dixon, Kingsley W.; Jersáková, Jana; Těšitelová, Tamara

    2015-01-01

    Background Seedling recruitment is essential to the sustainability of any plant population. Due to the minute nature of seeds and early-stage seedlings, orchid germination in situ was for a long time practically impossible to observe, creating an obstacle towards understanding seedling site requirements and fluctuations in orchid populations. The introduction of seed packet techniques for sowing and retrieval in natural sites has brought with it important insights, but many aspects of orchid seed and germination biology remain largely unexplored. Key Considerations The germination niche for orchids is extremely complex, because it is defined by requirements not only for seed lodging and germination, but also for presence of a fungal host and its substrate. A mycobiont that the seedling can parasitize is considered an essential element, and a great diversity of Basidiomycota and Ascomycota have now been identified for their role in orchid seed germination, with fungi identifiable as imperfect Rhizoctonia species predominating. Specificity patterns vary from orchid species employing a single fungal lineage to species associating individually with a limited selection of distantly related fungi. A suitable organic carbon source for the mycobiont constitutes another key requirement. Orchid germination also relies on factors that generally influence the success of plant seeds, both abiotic, such as light/shade, moisture, substrate chemistry and texture, and biotic, such as competitors and antagonists. Complexity is furthermore increased when these factors influence seeds/seedling, fungi and fungal substrate differentially. Conclusions A better understanding of germination and seedling establishment is needed for conservation of orchid populations. Due to the obligate association with a mycobiont, the germination niches in orchid species are extremely complex and varied. Microsites suitable for germination can be small and transient, and direct observation is difficult

  6. Effect of soil bulk density on forest tree seedlings

    NASA Astrophysics Data System (ADS)

    Kormanek, Mariusz; Banach, Jacek; Sowa, Paweł

    2015-01-01

    The paper presents the results of an analysis of the influence of soil bulk density in a forest nursery plot on the growth and quality parameters of Scots pine and European beech seedlings. Particular density variants were obtained using a tractor device exerting controlled pressure on the soil, while field examinations were performed on an area of `Kłaj' forest nursery in Niepołomice Forest District. Three series of plots were prepared for each species, applying a unit pressure of the values of 50, 100, 150, 200, 250 kPa, corresponding to the dry bulk density in the range of 1.03-1.19 g cm-3, and control plots without the pressure. Seeds of the examined species were sown on the prepared plots, and after 6 months of growth the seedlings were subjected to biometric analysis determining differentiation in root neck diameter, length of the above-ground part and root system, as well as dry mass of particular parts of the plant. The quality of the seedlings was also determined using the method of Schmidt-Vogt. The results obtained show that the change in dry bulk density soil significantly affected most of the growth parameters of the examined seedlings. Especially high negative correlations were obtained for the length and dry mass of the root system. A significant influence of dry bulk density variant on all growth parameters of Scots pine seedlings, and on some parameters of European beech was demonstrated. An increase in soil bulk density clearly caused also a deterioration of European beech seedlings quality

  7. The pea seedling mitochondrial Nε-lysine acetylome.

    PubMed

    Smith-Hammond, Colin L; Hoyos, Elizabeth; Miernyk, Ján A

    2014-11-01

    Posttranslational lysine acetylation is believed to occur in all taxa and to affect thousands of proteins. In contrast to the hundreds of mitochondrial proteins reported to be lysine-acetylated in non-plant species, only a handful have been reported from the plant taxa previously examined. To investigate whether this reflects a biologically significant difference or merely a peculiarity of the samples thus far examined, we immunoenriched and analyzed acetylated peptides from highly purified pea seedling mitochondria using mass spectrometry. Our results indicate that a multitude of mitochondrial proteins, involved in a variety of processes, are acetylated in pea seedlings. PMID:24780491

  8. SPATIAL EFFECTS OF RETENTION TREES ON MYCORRHIZAS OF DOUGLAS-FIR SEEDLINGS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Retention forestry places seedlings in proximity to residual trees, exposing seedlings to additional sources of ectomycorrhizal fungus (EMF) inoculum. To investigate this, Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were planted near (2-6 m) and far (16-30 m) from 44- to 72-year-ol...

  9. Hessian fly (Mayetiola destructor) interactions with barley, rice, and wheat seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A choice test revealed that Hessian fly adults deposited approximately three times more eggs on wheat seedlings than on barley or rice seedlings. On a barley seedling, 49.4% of eggs were deposited on either the abaxial leaf-surface or the coleoptile and first leaf-sheath (C&FLS), where newly hatche...

  10. Chromosome doubling of haploid maize seedlings by various in vitro treatments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A two-year study was conducted on methods for doubling haploid maize plants with elite temperate backgrounds following various seed treatments. Seedlings were treated with colchicine or other chemicals by 1) injecting plants and 2) a soak method using various seedling treatments. Treated seedlings...

  11. Impact of corn gluten meal on direct-seeded vegetable seedling establishment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn gluten meal (CGM) may be used as a preemergent or preplant-incorporated herbicide for organic weed control of young developing or emerging weed seedlings; unfortunately, CGM can also adversely impact seedling survival of certain direct-seeded vegetable crops. Various vegetable crop seedlings re...

  12. Seedling Vigor in Beta vulgaris: The Artistry of Germination

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  13. Seedling vigor in Beta vulgaris: The artistry of germination

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Emergence and stand establishment through the first 10 weeks after planting continue to be primary concerns of sugar beet growers. Our goal is to understand the genes and genetics of seedling vigor in order to overcome beet’s inherent disadvantages of small seed size and encapsulation in a corky fru...

  14. Soybean seedlings tolerate abrasion from air-propelled grit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    New tools for controlling weeds would be useful for soybean production in organic systems. Air-propelled abrasive grit is one such tool that performs well for in-row weed control in corn, but crop safety in soybean is unknown. We examined responses to abrasion by corn-cob grit of soybean seedlings a...

  15. Seedling emergence of horseweed in no-till

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Density of horseweed is increasing in no-till cropping systems because horseweed seed is transported by wind and seedlings can establish from seeds lying on the soil surface. Also, horseweed has developed resistance to commonly-used herbicides, thus control tactics are often ineffective. This repo...

  16. The vestigial root of dodder (Cuscuta pentagona) seedlings.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seedlings of dodder have no leaves nor cotyledons and the terminal root-like structure lasts only a few days before death. Structural and biochemical studies indicate that the terminal appendage of the dodder, although differentiated from the shoot, has few characteristics of root tissue. The root...

  17. Weed Seedling Emergence and Survival as Affected by Crop Canopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study measured impact of cool-season crops on seedling emergence, survival, and seed production of weeds common in corn and soybean. Weed dynamics were monitored in permanently-marked quadrats in winter wheat, spring wheat, and canola. Three species, green foxtail, yellow foxtail, and common ...

  18. Validation of a metabolic cotton seedling emergence model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A seedling emergence model based on thermal dependence of enzyme activity in germinating cotton was developed. The model was validated under both laboratory and field conditions with several cotton lines under diverse temperature regimes. Four commercial lines were planted on four dates in Lubbock T...

  19. Utilization of Amygdalin during Seedling Development of Prunus serotina.

    PubMed Central

    Swain, E.; Poulton, J. E.

    1994-01-01

    Cotyledons of mature black cherry (Prunus serotina Ehrh.) seeds contain the cyanogenic diglucoside (R)-amygdalin. The levels of amygdalin, its corresponding monoglucoside (R)-prunasin, and the enzymes that metabolize these cyanoglycosides were measured during the course of seedling development. During the first 3 weeks following imbibition, cotyledonary amygdalin levels declined by more than 80%, but free hydrogen cyanide was not released to the atmosphere. Concomitantly, prunasin, which was not present in mature, ungerminated seeds, accumulated in the seedling epicotyls, hypocotyls, and cotyledons to levels approaching 4 [mu]mol per seedling. Whether this prunasin resulted from amygdalin hydrolysis remains unclear, however, because these organs also possess UDPG:mandelonitrile glucosyltransferase, which catalyzes de novo prunasin biosynthesis. The reduction in amygdalin levels was paralleled by declines in the levels of amygdalin hydrolase (AH), prunasin hydrolase (PH), mandelonitrile lyase (MDL), and [beta]-cyanoalanine synthase. At all stages of seedling development, AH and PH were localized by immunocytochemistry within the vascular tissues. In contrast, MDL occurred mostly in the cotyledonary parenchyma cells but was also present in the vascular tissues. Soon after imbibition, AH, PH, and MDL were found within protein bodies but were later detected in vacuoles derived from these organelles. PMID:12232341

  20. Burst of ethylene upon horizontal placement of tomato seedlings

    NASA Technical Reports Server (NTRS)

    Harrison, M.; Pickard, B. G.

    1984-01-01

    Seedlings of Lycopersicon esculentum Mill. cv Rutgers emit a pulse of ethylene during the first 2 to 4 minutes following horizontal placement. Because this burst appears too rapid and brief to be mediated by increase in net activity of 1-aminocyclopropane-1-carboxylic acid synthase, it might result form accelerated transformation of vacuolar 1-aminocyclopropane-1-carboxylic acid to ethylene.

  1. [Characterization of growth-promoting rhizobacteria in Eucalyptus nitens seedlings].

    PubMed

    Angulo, Violeta C; Sanfuentes, Eugenio A; Rodríguez, Francisco; Sossa, Katherine E

    2014-01-01

    Rhizospheric and endophytic bacteria were isolated from the rizosphere and root tissue of Eucalyptus nitens. The objective of this work was to evaluate their capacity to promote growth in seedlings of the same species under greenhouse conditions. The isolates that improved seedling growth were identified and characterized by their capacity to produce indoleacetic acid (IAA), solubilize phosphates and increase 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. One hundred and five morphologically different strains were isolated, 15 of which promoted E. nitens seedling growth, significantly increasing the height (50%), root length (45%) as well as the aerial and root dry weight (142% and 135% respectively) of the plants. Bacteria belonged to the genus Arthrobacter, Lysinibacillus, Rahnella and Bacillus. Isolates A. phenanthrenivorans 21 and B. cereus 113 improved 3.15 times the emergence of E. nitens after 12 days, compared to control samples. Among isolated R. aquatilis, 78 showed the highest production of IAA (97.5±2.87 μg/ml) in the presence of tryptophan and the highest solubilizer index (2.4) for phosphorus, while B. amyloliquefaciens 60 isolate was positive for ACC deaminase activity. Our results reveal the potential of the studied rhizobacteria as promoters of emergence and seedling growth of E. nitens, and their possible use as PGPR inoculants, since they have more than one mechanism associated with plant growth promotion. PMID:25576419

  2. Evaluation of a metabolic cotton seedling emergence model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A model for cotton seedling emergence (MaGi) based on malate synthase kinetics was evaluated in the field at two locations, Lubbock and Big Spring, TX. Cotton, cvar. DP 444, was planted through the early spring and into typical planting times for the areas. Soil temperatures at seed depth was used a...

  3. Heat Stress Screening of Peanut Seedlings for Acquired Thermotolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to develop a user-friendly and medium throughput laboratory protocol using acquired thermotolerance (ATT) in peanut seedlings as a measure of one mechanism of heat stress tolerance. Sixteen genotypes, including selected accessions of the U.S. peanut min...

  4. Identification of seedling cabbages and weeds using hyperspectral imaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  5. Regulation of Flavonoid Biosynthetic Genes in Germinating Arabidopsis Seedlings.

    PubMed Central

    Kubasek, WL; Shirley, BW; McKillop, A; Goodman, HM; Briggs, W; Ausubel, FM

    1992-01-01

    Many higher plants, including Arabidopsis, transiently display purple anthocyanin pigments just after seed germination. We observed that steady state levels of mRNAs encoded by four flavonoid biosynthetic genes, PAL1 (encoding phenylalanine ammonia-lyase 1), CHS (encoding chalcone synthase), CHI (encoding chalcone isomerase), and DFR (encoding dihydroflavonol reductase), were temporally regulated, peaking in 3-day-old seedlings grown in continuous white light. Except for the case of PAL1 mRNA, mRNA levels for these flavonoid genes were very low in seedlings grown in darkness. Light induction studies using seedlings grown in darkness showed that PAL1 mRNA began to accumulate before CHS and CHI mRNAs, which, in turn, began to accumulate before DFR mRNA. This order of induction is the same as the order of the biosynthetic steps in flavonoid biosynthesis. Our results suggest that the flavonoid biosynthetic pathway is coordinately regulated by a developmental timing mechanism during germination. Blue light and UVB light induction experiments using red light- and dark-grown seedlings showed that the flavonoid biosynthetic genes are induced most effectively by UVB light and that blue light induction is mediated by a specific blue light receptor. PMID:12297632

  6. Cotton seedling abrasion and recovery from wind blown sand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of hectares of crops are exposed to wind blown sand abrasion each year and in many instances the damage is thought to be severe enough to require replanting. The goal of this study was to determine the effects of wind blown sand abrasion duration on cotton (Gossypium hirsutum L.) seedlings...

  7. Starch bioengineering affects cereal grain germination and seedling establishment

    PubMed Central

    Hebelstrup, Kim H.; Blennow, Andreas

    2014-01-01

    Cereal grain germination is central for plant early development, and efficient germination has a major role in crop propagation and malting. Endosperm starch is the prime energy reserve in germination and seedling establishment. In this study, it was hypothesized that optimized starch granule structure, and not only the endosperm starch content per se, is important for germination and seedling establishment. For that purpose, wild-type (WT), and specifically engineered degradable hyperphosphorylated (HP) starch and more resistant amylose-only (AO) starch barley lines were used. The transgenics showed no severe phenotypes and the WT and HP lines degraded the starch similarly, having 30% residual starch after 12 d of germination. However, the AO line showed significant resistance to degradation, having 57% residual starch. Interestingly, protein and β-glucan (BG) degradation was stimulated for both HP and AO lines as compared with the WT. At late seedling establishment stages, specific sugars were rapidly consumed in the AO line. α-Amylase activity was distinctly suppressed in both the HP and the AO lines. Pre-germination β-amylase deposition was low in the AO grains and β-amylase was generally suppressed in both HP and AO lines throughout germination. As further supported by scanning electron microscopy and histochemical analyses on grain and seedlings, it was concluded that inadequate starch granule deposition in combination with the suppressed hydrolase activity leads to temporal and compensating re-direction of starch, sugar, and protein catabolism important to maintain metabolic dynamics during grain germination and seedling establishment. PMID:24642850

  8. Pathogenicity of the pinewood nematode, Bursaphelenchus xylophilus, to Japanese larch, Larix kaempferi, seedlings.

    PubMed

    Mamiya, Y; Shoji, T

    2009-06-01

    Pathogenicity of the pine wood nematode, Bursaphelenchus xylophilus, to Japanese larch, Larix kaempferi, seedlings was tested with inoculation experiments under nursery conditions. Water suspensions of nematodes (mixed stages cultured on Botrytis cinerea or dispersal fourth-stage juveniles (DJ4) extracted from the adult Japanese pine sawyer, Monochamus alternatus) were injected into the stems of 2- and 3-year-old Japanese larch and Japanese black pine, Pinus thunbergii, seedlings growing in a nursery. In another treatment, Japanese pine sawyer adults holding DJ4 were released under a net that covered the upper half of the seedlings. Regardless of nematode inoculation method, Japanese larch seedlings were as susceptible as Japanese black pine seedlings to B. xylophilus under nursery conditions. The rate of disease development was similar on larch and pine seedlings. Nematode population densities were lower in the stems of dead larch seedlings than in the stems of dead pine seedlings. Histopathological observations revealed that the distribution of nematodes in the stems of dead larch seedlings was mostly limited to the cortex, phloem and cambial zone. Traumatic resin canal formation was one of the most characteristic symptoms in larch seedlings which was dissimilar to that in pine seedlings. PMID:22661789

  9. Biological seed priming mitigates the effects of water stress in sunflower seedlings.

    PubMed

    Singh, Narsingh Bahadur; Singh, Deepmala; Singh, Amit

    2015-04-01

    The sunflower (Helianthus annuus L. cv. PAC 36) seedlings were inoculated with plant growth promoting rhizobacteria (PGPR), viz. Azotobacter chroococcum (A+), Bacillus polymyxa (B+), separately and in combination of the two (AB+). Relative water content and seedling growth were maximum in AB+ seedlings under control. Water stress significantly decreased the RWC, growth and dry mass of non-inoculated seedlings. However, inoculated seedlings maintained higher growth even under water stress. Pigments and protein contents decreased under water stress, but higher amount of the same was observed in stressed AB+ seedlings. Enhanced activity of nitrate reductase was recorded in AB+ seedlings with maximum in control. Water stress significantly decreased the nitrate reductase activity. A significant increase in the activity of superoxide dismutase (SOD) in leaves was recorded under water stress except in B+ with maximum increase in non-inoculated seedlings. Catalase (CAT) activity decreased in stressed non-inoculated seedlings while increased in the leaves of A+ and AB+ seedlings. Almost similar trends were recorded for both leaves and cotyledons. PGPR improved the water status in stressed seedlings and thereby physiological and biochemical parameters and thus ameliorated the severe effects of water stress. PMID:25964714

  10. Effects of seed traits variation on seedling performance of the invasive weed, Ambrosia artemisiifolia L.

    NASA Astrophysics Data System (ADS)

    Ortmans, William; Mahy, Grégory; Monty, Arnaud

    2016-02-01

    Seedling performance can determine the survival of a juvenile plant and impact adult plant performance. Understanding the factors that may impact seedling performance is thus critical, especially for annuals, opportunists or invasive plant species. Seedling performance can vary among mothers or populations in response to environmental conditions or under the influence of seed traits. However, very few studies have investigated seed traits variations and their consequences on seedling performance. Specifically, the following questions have been addressed by this work: 1) How the seed traits of the invasive Ambrosia artemisiifolia L. vary among mothers and populations, as well as along the latitude; 2) How do seed traits influence seedling performance; 3) Is the influence on seedlings temperature dependent. With seeds from nine Western Europe ruderal populations, seed traits that can influence seedling development were measured. The seeds were sown into growth chambers with warmer or colder temperature treatments. During seedling growth, performance-related traits were measured. A high variability in seed traits was highlighted. Variation was determined by the mother identity and population, but not latitude. Together, the temperature, population and the identity of the mother had an effect on seedling performance. Seed traits had a relative impact on seedling performance, but this did not appear to be temperature dependent. Seedling performance exhibited a strong plastic response to the temperature, was shaped by the identity of the mother and the population, and was influenced by a number of seed traits.

  11. Effects of arbuscular mycorrhizae on water stress tolerance of big sagebrush seedlings

    SciTech Connect

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

    1998-12-31

    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 conducted 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.

  12. 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. PMID:17402238

  13. [Effects of arbuscular mycorrhizal fungus on the seedling growth of grafted watermelon and the defensive enzyme activities in the seedling roots].

    PubMed

    Chen, Ke; Sun, Ji-Qing; Liu, Run-Jin; Li, Min

    2013-01-01

    A greenhouse pot experiment was conducted to study the effects of arbuscular mycorrhizal fungus Glomus versiforme on the seedling growth and root membrane permeability, malondiadehyde (MDA) content, and defensive enzyme activities of non-grafted and grafted watermelon growing on the continuously cropped soil. Inoculation with G. versiforme increased the seedling biomass and root activity significantly, and decreased the root membrane permeability and MDA content. The seedling shoot fresh mass, shoot dry mass, and root activity of non-grafted watermelon increased by 57.6%, 60.0% and 142.1%, and those of grafted watermelon increased by 26.7%, 28.0% and 11.0%, respectively, compared with no G. versiforme inoculation. The root membrane permeability of non-grafted seedlings (C), grafted seedlings (G), non-grafted seedlings inoculated with G. versiforme (C+M), and grafted seedlings inoculated with G. versiforme (G+M) was in the order of C >G>C+M>G+M, and the root MDA content was in the sequence of C>G>G+M>C+M. G. versiforme inoculation increased the root phenylalanine ammonialyase (PAL), catalase (CAT), peroxidase (POD), beta-1,3-glucanase and chitinase activities of grafted and non-grafted seedlings significantly, and the peaks of the POD, PAL and beta-1,3-glucanase activities in the mycorrhizal roots appeared about two weeks earlier than those in the non-inoculated roots. These results indicated that inoculating arbuscular mycorrhizal fungus G. versiforme could activate the defensive enzyme activities of non-grafted and grafted watermelon seedlings, enable the seedling roots to produce rapid response to adversity, and thus, improve the capability of watermelon seedling against continuous cropping obstacle. PMID:23718001

  14. 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

  15. 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.

  16. Effects of invasive rats and burrowing seabirds on seeds and seedlings on New Zealand islands.

    PubMed

    Grant-Hoffman, Madeline N; Mulder, Christa P H; Bellingham, Peter J

    2010-04-01

    Rats (Rattus rattus, Rattus norvegicus, Rattus exulans) are important invaders on islands. They alter vegetation indirectly by preying on burrowing seabirds. These seabirds affect vegetation through nutrient inputs from sea to land and physical disturbance through trampling and burrowing. Rats also directly affect vegetation though consumption of seeds and seedlings. Seedling communities on northern New Zealand islands differ in composition and densities among islands which have never been invaded by rats, are currently invaded by rats, or from which rats have been eradicated. We conducted experimental investigations to determine the mechanisms driving these patterns. When the physical disturbance of seabirds was removed, in soils collected from islands and inside exclosures, seedling densities increased with seabird burrow density. For example, seedling densities inside exclosures were 10 times greater than those outside. Thus the negative effects of seabirds on seedlings, by trampling and uprooting, overwhelm the potentially beneficial effects of high levels of seed germination, seedling emergence, and possibly seed production, which result from seed burial and nutrient additions. Potential seedling density was reduced on an island where rats were present, germination of seeds from soils of this island was approximately half that found on other islands, but on this island seedling density inside exclosures was 7 times the density outside. Although the total negative effects of seabirds and rats on seedling densities are similar (reduced seedling density), the differences in mechanisms and life stages affected result in very different filters on the plant community. PMID:19921273

  17. 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.

  18. A technique for collection of exudate from pea seedlings

    NASA Technical Reports Server (NTRS)

    Hanson, S. D.; Cohen, J. D.; Bandurski, R. S. (Principal Investigator)

    1985-01-01

    Ethylenediaminetetraacetic acid (EDTA), at concentrations higher than 1.0 millimolar, is phytotoxic to etiolated seedlings of Pisum sativum. Substantial vascular exudation from pea epicotyls could be obtained without tissue damage at 0.5 millimolar EDTA if the solution was buffered at pH 7.5 with sodium N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid. Treated seedlings exuded 950 micrograms (leucine equivalents) of ninhydrin-positive material per day and 870 micrograms (glucose equivalents) of anthrone-positive material per day. Amino acid analysis showed the exudate to have glutamine as the major amido nitrogen containing compound and sucrose was shown to be the major sugar. Radiolabeled tryptophan and sucrose applied to cotyledons were transferred through the epicotyl and into the collection medium. The pH profile for exudation shows half maximal exudation at pH 7.2, indicating the promotion of exudation by EDTA is probably not due simply to Ca2+ chelation.

  19. Growth Distribution during Phototropism of Arabidopsis thaliana Seedlings.

    PubMed Central

    Orbovic, V.; Poff, K. L.

    1993-01-01

    The elongation rates of two opposite sides of hypocotyls of Arabidopsis thaliana seedlings were measured during phototropism by using an infrared imaging system. In first positive phototropism, second positive phototropism, and red light-enhanced first positive phototropism, curvature toward the light source was the result of an increase in the rate of elongation of the shaded side and a decrease in the rate of elongation of the lighted side of the seedlings. The phase of straightening that followed maximum curvature resulted from a decrease in the elongation rate of the shaded side and an increase in the elongation rate of the lighted side. These data for the three types of blue light-induced phototropism tested in this study and for the phase of straightening are all clearly consistent with the growth rate changes predicted by the Cholodny-Went theory. PMID:12231922

  20. G-proteins in etiolated Avena seedlings. Possible phytochrome regulation.

    PubMed

    Romero, L C; Sommer, D; Gotor, C; Song, P S

    1991-05-01

    The molecular mechanism of light signal transduction in plants mediated by the photosensor phytochrome is not well understood. The possibility that phytochrome initiates the signal transduction chain by modulating a G-protein-like receptor is examined in the present work. Etiolated Avena seedlings contain G-proteins as examined in terms of the binding of GTP as well as by cross-reaction with mammalian G-protein antibodies. The binding of GTP was regulated in vivo by red/far-red light. The possible involvement of G-proteins in the phytochrome-mediated signal transduction in etiolated Avena seedlings has been implicated from the study of the light regulated expression of the Cab and phy genes. PMID:1903719

  1. Phytotoxicity of arsenic compounds on crop plant seedlings.

    PubMed

    Yoon, Youngdae; Lee, Woo-Mi; An, Youn-Joo

    2015-07-01

    The effects of inorganic and organic arsenic on the germination and seedling growth of 10 crop plants were investigated to elucidate the relationship between toxicity and the arsenic chemical states. Two types of soils, soil A and B, were also tested to determine how physicochemical properties of soils were related to toxicity of arsenic and the sensitivity of the plants. All tested plant species, except mung bean and cucumber, showed inhibition of germination by two types of inorganic arsenic, arsenite, and arsenate, while the organic arsenic compound, dimethylarsinic acid (DMA), had no inhibitory effects on plants in soil A. In contrast, the growth of seedlings of all 10 plant species was sensitive to the presence of arsenic. The sensitivity of the plants toward inorganic arsenic compounds showed similar trends but differed for DMA. Overall, seedling growth was a more sensitive endpoint to arsenic toxicity than germination, and the relative toxicity of arsenic compounds on plants was arsenite > DMA > arsenate. Interestingly, the sensitivity of wheat varied significantly when the soil was changed, and the DMA was most toxic rather than arsenite in soil B. Thus, the systematic study employed here provides insights into the mechanisms of arsenic toxicity in different plant species and the role of physicochemical properties of soils. PMID:25791266

  2. Organic Matter Loading Affects Lodgepole Pine Seedling Growth

    NASA Astrophysics Data System (ADS)

    Wei, Xiaohua; Li, Qinglin; Waterhouse, M. J.; Armleder, H. M.

    2012-06-01

    Organic matter plays important roles in returning nutrients to the soil, maintaining forest productivity and creating habitats in forest ecosystems. Forest biomass is in increasing demand for energy production, and organic matter has been considered as a potential supply. Thus, an important management question is how much organic matter should be retained after forest harvesting to maintain forest productivity. To address this question, an experimental trial was established in 1996 to evaluate the responses of lodgepole pine seedling growth to organic matter loading treatments. Four organic matter loading treatments were randomly assigned to each of four homogeneous pine sites: removal of all organic matter on the forest floor, organic matter loading quantity similar to whole-tree-harvesting residuals left on site, organic matter loading quantity similar to stem-only-harvesting residuals, and organic matter loading quantity more similar to what would be found in disease- or insect-killed stands. Our 10-year data showed that height and diameter had 29 and 35 % increase, respectively, comparing the treatment with the most organic matter loading to the treatment with the least organic matter loading. The positive response of seedling growth to organic matter loading may be associated with nutrients and/or microclimate change caused by organic matter, and requires further study. The dynamic response of seedling growth to organic matter loading treatments highlights the importance of long-term studies. Implications of those results on organic matter management are discussed in the context of forest productivity sustainability.

  3. Purine Synthesis and Catabolism in Soybean Seedlings 1

    PubMed Central

    Polayes, Deborah A.; Schubert, Karel R.

    1984-01-01

    The ureides, allantoin and allantoic acid, are the major nitrogenous substances transported within the xylem of N2-fixing soybeans (Glycine max L. Merr. cv Amsoy 71). The ureides accumulated in the cotyledons, roots and shoots of soybean seedlings inoculated with Rhizobium or grown in the presence of 10 millimolar nitrate. The patterns of activity for uricase and allantoinase, enzymes involved in ureide synthesis, were positively correlated with the accumulation of ureides in the roots and cotyledons. Allopurinol and azaserine inhibited ureide production in 3-day-old cotyledons while no inhibition was observed in the roots. Incubation of 4-day-old seedlings with [14C]serine indicated that in the cotyledons ureides arose via de novo synthesis of purines. The source of ureides in both 3- and 4-day-old roots was probably the cotyledons. The inhibition of ureide accumulation by allopurinol but not azaserine in 8-day-old cotyledons suggested that ureides in these older cotyledons arose via nucleotide breakdown. Incubation of 8-day-old plants with [14C]serine suggested that the roots had acquired the capability to synthesize ureides via de novo synthesis of purines. These data indicate that both de novo purine synthesis and nucleotide breakdown are involved in the production of ureides in young soybean seedlings. PMID:16663743

  4. Effects of gravel mulch on emergency of galleta grass seedlings

    SciTech Connect

    Winkel, V.K.; Medrano, J.C.; Stanley, C.; Walo, M.D.

    1993-02-01

    Gravel mulches show promise as effective material on the US Dept. of Energy Nevada Test Site for stabilizing erosive soils and aiding plant establishment by conserving soil water. A greenhouse study was implemented to determine the effects of gravel mulch on seedling emergence and soil water, and optimal depths of gravel for various native plant species. Greenhouse flats were sown with seeds of nine species of native grasses, forbs, and shrubs. The flats were then treated with a variety of mulch treatments including, no mulch, a 1-cm layer of soil over seeds, and 2 to 3-cm and 4 to 5-cm layers of 3 to 25-mm mixed gravel. Superimposed over these treatments were 3 irrigation treatments. Seedling density data was collected daily, and soil water was monitored daily with the gravimetric method. This study showed that under a variety of soil water conditions, a 2--3 cm gravel layer may aid emergence of galleta grass. Results from this study also demonstrated that a deeper layer of gravel (4--5 cm) prohibits emergence, probably because it acts as a physical barrier to the seedlings. Galleta grass emergence can be used as a model for how other species might respond to these seedbed and irrigation treatments, provided they have adequate germination and are exposed to similar environmental conditions.

  5. Turnover of dhurrin in green sorghum seedlings. [Sorghum bicolor

    SciTech Connect

    Adewusi, S.R.A. )

    1990-11-01

    The turnover of dhurrin in green seedlings of Sorghum bicolor (Linn) Moench var Redland x Greenleaf, Sudan 70 has been investigated using glyphosate and pulse-labeling studies with {sup 14}C-tyrosine and ({sup 14}C)shikimic acid. The rate of dhurrin breakdown was 4.8 nanomoles per hour in the shoot and 1.4 nanomoles per hour in the root. The rate of dhurrin accumulation in the shoot of 4- to 5-day-old seedlings was high but decreased with age until at the peak period of dhurrin accumulation, the rates of dhurrin synthesis and breakdown were equal. Using a first order equation (an approximation) the rate of dhurrin synthesis (which equals accumulation plus breakdown rates) was 17.4 nanomoles per hour in the shoot and 4.1 nanomoles per hour in the root. In both tissues, the breakdown rate was between 27 and 34% of their synthetic capacity within the experimental period. Dhurrin synthesis in green sorghum seedlings occurred in both the light and dark photoperiods but was faster in the dark period. The result is discussed in relation to the possible metabolic roles of the turnover.

  6. Effects of Ectomycorrhizal Fungi on Growth of Seedlings of Pinus densiflora.

    PubMed

    Sim, Mi-Yeong; Eom, Ahn-Heum

    2006-12-01

    This study was conducted to investigate the different effects of ectomycorrhizal fungal (ECMF) species on the growth of seedlings of Pinus densiflora, and the effects of ECMF diversity on plant productivity. A total of five species of ECMF were isolated from root tips of pine seedlings collected from Mt. Songni and used as inocula. Pots containing pine seedlings were inoculated with either a single ECMF species or a mixture of five ECMF species. All of the seedlings formed ECM on their roots except for the control plants. The pine seedlings' growth responses varied by the different ECMF species. Also, pine seedlings inoculated with a mixture of five ECMF species showed the highest growth response. The results of the study suggest that the colonization of diverse species of ECMF will increase plant productivity, and the selection of suitable ECMF species could be an important factor for plant growth. PMID:24039497

  7. Influence of Merosesquiterpenoids from Marine Sponges on Seedling Root Growth of Agricultural Plants.

    PubMed

    Chaikina, Elena L; Utkina, Natalia K; Anisimov, Mikhail M

    2016-01-01

    The impact of the merosesquiterpenoids avarol (1), avarone (2), 18-methylaminoavarone (3), melemeleone A (4), isospongiaquinone (5), ilimaquinone (6), and smenoquinone (7), isolated from marine sponges of the Dictyoceratida order, was studied on the root growth of seedlings of buckwheat (Fagopyrumesculentum Moench), wheat (Triticumaestivum L.), soy (Glycine max (L.) Merr.), and barley (Hordeumvulgare L.). Compounds 2and 6 were effective for the root growth of wheat seedlings, compound 3 stimulated the root growth of seedlings of buckwheat and soy, compound 4 affected the roots of barley seedlings, and compound 5 stimulated the root growth of seedlings of buckwheat and barley. Compounds 1 and 7 showed no activity on the root growth of the seedlings of any of the studied plants. The stimulatory effect depends on the chemical structure of the compounds and the type of crop plant. PMID:26996006

  8. Survival of planted tupelo seedlings in F- and H-Area tree-kill zones

    SciTech Connect

    Nelson, E.A.; Rogers, V.A.

    1995-01-01

    Swamp tupelo seedlings were planted in four areas which experienced previous tree mortality at the seeplines of the F- and H-Area Seepage Basins. The sites represented a range in severity of impact and stage of recovery. Seedlings were planted in February of 1994 and followed through the first growing season in the field. Survival on all sites through the first growing season was excellent, with greater than 92% of the seedlings still alive. Most seedlings appeared healthy with few external signs of stress. The performance of the seedlings will be followed in subsequent years to determine the physical state of the soil environment on seedling growth. Hopefully, the results will indicate that artificial reforestation can begin on similarly impacted sites prior to the beginning of natural revegetation of the site.

  9. Root graviresponsiveness and columella cell structure in carotenoid-deficient seedlings of Zea mays

    NASA Technical Reports Server (NTRS)

    Moore, R.; McClelen, C. E.

    1985-01-01

    Root graviresponsiveness in normal and carotenoid-deficient mutant seedlings of Zea mays was not significantly different. Columella cells in roots of mutant seedlings were characterized by fewer, smaller, and a reduced relative volume of plastids as compared to columella cells of normal seedlings. Plastids in columella cells of mutant seedlings possessed reduced amounts of starch. Although approximately 10 per cent of the columella cells in mutant seedlings lacked starch, their plastids were located at the bottom of the cell. These results suggest that (i) carotenoids are not necessary for root gravitropism, (ii) graviresponsiveness is not necessarily proportional to the size, number, or relative volume of plastids in columella cells, and (iii) sedimentation of plastids in columella cells may not result directly from their increased density due to starch content. Plastids in columella cells of normal and mutant seedlings were associated with bands of microtubule-like structures, suggesting that these structures may be involved in 'positioning' plastids in the cell.

  10. Photosynthesis and transpiration of loblolly pine seedlings as influenced by moisture-stress conditioning

    SciTech Connect

    Seiler, J.R.; Johnson, J.D.

    1985-01-01

    One-yr-old seedlings were exposed to 8 wk of moisture stress conditioning (MSC); seedlings were watered only when pre-dawn needle water potential fell below -1.4 MPa. Water was then withheld and photosynthesis and transpiration rates recorded. Photosynthesis in well-watered controls and MSC seedlings was reduced to zero in 12 and 17 days respectively. Seedlings were harvested and water use efficiency calculated using photosynthesis and transpiration data; it was expressed as mg of CO/sub 2/ fixed per g of water lost. Seedlings exposed to MSC continued to photosynthesize to much lower needle water potentials. This response is at least partly attributed to the significant decrease (0.45 MPa) in needle osmotic potential found in MSC seedlings, which were able to maintain turgor to lower needle water potentials. Transpiration rate decreased 30% and water use efficiency increased 67% as a result of MSC. 26 references.

  11. Kinetics for Phototropic Curvature by Etiolated Seedlings of Arabidopsis thaliana 1

    PubMed Central

    Orbović, Vladimir; Poff, Kenneth 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° about 80 minutes after stimulation. The seedlings then curved upward again or straightened by about 6° 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. PMID:11538373

  12. 3D vision sensor and its algorithm on clone seedlings plant system

    NASA Astrophysics Data System (ADS)

    Hayashi, Jun-ichiro; Hiroyasu, Takehisa; Hojo, Hirotaka; Hata, Seiji; Okada, Hiroshi

    2007-01-01

    Today, vision systems for robots had been widely applied to many important applications. But 3-D vision systems for industrial uses should face to many practical problems. Here, a vision system for bio-production has been introduced. Clone seedlings plants are one of the important applications of biotechnology. Most of the production processes of clone seedlings plants are highly automated, but the transplanting process of the small seedlings plants cannot be automated because the shape of small seedlings plants are not stable and in order to handle the seedlings plants it is required to observe the shapes of the small seedlings plants. In this research, a robot vision system has been introduced for the transplanting process in a plant factory.

  13. [Radiobiological characteristics of chilled seedlings as an object for inflight experiments].

    PubMed

    Shaĭdorov, Iu I; Miller, A T; Fischere, G A

    1975-01-01

    It is recommended to use for experimentation cooled plant seedlings in the stage of delayed growth. Cooled seedlings have a high sensitivity to the environmental effects and can be used in long-term (up to 1-2 months) experiments. The influence of suboptimal temperatures on the radiosensitivity of seedlings, the development of radiation injury and maintenance of the radiobiological effect is described. PMID:1214486

  14. Analysis of the relationship between photosynthetic photon flux density and natural Taxus baccata seedlings occurrence

    NASA Astrophysics Data System (ADS)

    Iszkuło, Grzegorz; Boratyński, Adam

    2006-01-01

    The aim of the present work was to analyse the relationship of seedlings and saplings of Taxus baccata to the photosynthetic photon flux density (PPFD) reaching the forest floor under natural conditions. Two permanent plots, subdivided into 1 × 1 m square plots, were established in a naturally regenerating population of T. baccata formed during last decades in the Kórnik Arboretum, Poland. All seedlings in every 1 × 1 m plots were counted. Relative PPFD was measured for every plot at the canopy height of the yew seedlings. The dependence of seedling density upon PPFD was examined. We found, that the frequency of the smallest seedlings (to 6.0 cm tall) was highest in the most shaded plots and decreased in plots with increasing PPFD. Thus, the youngest yew seedlings can germinate and grow in very shady conditions. However, the older seedlings (6.1-25.0 and 25.1-100.0 classes) were observed most frequently in 2-7% PPFD. The small numbers of older, taller seedlings in deep shade likely indicate a higher mortality rate of seedlings less than 6 cm in height without promotion to the next height class. Probably the low value of PPFD under the canopy of the stand significantly reduces the competition of other plants with the youngest yew seedlings. At higher light levels they may not be able to compete with more light-demanding plants, such as herbs and seedlings of broad-leaved trees. The seedlings of the second (6.1-25.0 cm) and third (25.1-100.0 cm) height classes were observed most frequently in the plots with 2-7% PPFD ( Fig. 1b and c).

  15. Controlling herbaceous competition in pasture planted with loblolly pine seedlings. Forest Service research note

    SciTech Connect

    Haywood, J.D.

    1995-09-01

    Three treatments designed to control herbaceous vegetation competing with loblolly pine (Pinus taeda L.) seedlings planted in grazed and ungrazed pasture were tested. Effects of the treatments on seedling survival and growth during the first 3 years after planting were determined. The treatments were directed application of herbicides (glyphosate in the first 2 years and hexazinone in the third year), rotary mowing, and mulching with pine straw around individual pine seedlings.

  16. Effects of cryopreservation of recalcitrant Amaryllis belladonna zygotic embryos on vigor of recovered seedlings: a case of stress 'hangover'?

    PubMed

    Berjak, Patricia; Pammenter, Norman W

    2010-06-01

    Cryopreservation is the most promising long-term storage option for recalcitrant (i.e. desiccation-sensitive) seed germplasm; however, its effects on the vigor of recovered seedlings are unclear. This study looked at the vigor of seedlings recovered from partially dried (D) and cryopreserved (C) recalcitrant zygotic embryos (ZEs) of Amaryllis belladonna. Seedlings recovered from fresh (F), D- and C-embryos were regenerated in vitro, hardened-off ex vitro and then exposed to 12 days of watering (W) or 8 days of water deficit (S), followed by 3 days of re-watering. Seedling vigor was assessed in terms of physiological and growth responses to the imposed water stress. Compared with F-embryos, partial dehydration and cryopreservation reduced the number of embryos that produced seedlings, as well as the subsequent in vitro biomass of these seedlings. DW- and CW-seedlings (i.e. seedlings recovered from dried and cryopreserved ZEs that were watered for 12 days) exhibited lower CO(2)-assimilation rates and abnormal root growth. Stomatal density was also lower in C-seedlings. DS- and CS-seedlings were exposed to persistent low leaf water and pressure potentials and unlike FS-seedlings, displayed signs of having incurred damage to their photosynthetic machinery. CS-seedlings were less efficient at adjusting leaf water potential to meet transpirational demands and more susceptible to persistent turgor loss than DS- and FS-seedlings. DS-seedlings performed slightly better than CS-seedlings but drought-induced seedling mortality in both these treatments was higher than FS-seedlings. These results suggest that seedlings recovered from partially dried and cryopreserved embryos were less vigorous and more susceptible to hydraulic failure than those from fresh ZEs. PMID:20113434

  17. Community-Wide Spatial and Temporal Discordances of Seed-Seedling Shadows in a Tropical Rainforest

    PubMed Central

    Rother, Débora Cristina; Pizo, Marco Aurélio; Siqueira, Tadeu; Rodrigues, Ricardo Ribeiro; Jordano, Pedro

    2015-01-01

    Several factors decrease plant survival throughout their lifecycles. Among them, seed dispersal limitation may play a major role by resulting in highly aggregated (contagious) seed and seedling distributions entailing increased mortality. The arrival of seeds, furthermore, may not match suitable environments for seed survival and, consequently, for seedling establishment. In this study, we investigated spatio-temporal patterns of seed and seedling distribution in contrasting microhabitats (bamboo and non-bamboo stands) from the Brazilian Atlantic Forest. Spatial distribution patterns, spatial concordance between seed rain and seedling recruitment between subsequent years in two fruiting seasons (2004–2005 and 2007–2009), and the relation between seeds and seedlings with environmental factors were examined within a spatially-explicit framework. Density and species richness of both seeds and seedlings were randomly distributed in non-bamboo stands, but showed significant clustering in bamboo stands. Seed and seedling distributions showed across-year inconsistency, suggesting a marked spatial decoupling of the seed and seedling stages. Generalized linear mixed effects models indicated that only seed density and seed species richness differed between stand types while accounting for variation in soil characteristics. Our analyses provide evidence of marked recruitment limitation as a result of the interplay between biotic and abiotic factors. Because bamboo stands promote heterogeneity in the forest, they are important components of the landscape. However, at high densities, bamboos may limit recruitment for the plant community by imposing marked discordances of seed arrival and early seedling recruitment. PMID:25856393

  18. Auxins Induce Tryptophan Decarboxylase Activity in Radicles of Catharanthus Seedlings 1

    PubMed Central

    Aerts, Rob J.; Alarco, Anne-Marie; De Luca, Vincenzo

    1992-01-01

    Germinating seedlings of Catharanthus roseus produce monoterpenoid indole alkaloids as a result of a transient increase of tryptophan decarboxylase (TDC) activity. The influence of auxins on this transient rise of TDC activity was studied. External application of indolebutyric acid or 2,4-dichlorophenoxyacetic acid at a concentration of 20 to 40 μm enhanced and prolonged the rise in TDC activity in developing seedlings. Auxin treatment also influenced the morphology of the seedlings; it induced a shortening and thickening of the hypocotyl and the radicle and promoted the initiation of lateral roots in the radicle. During development, the radicles of auxin-treated seedlings displayed a gradual increase in TDC activity that was absent in the radicles of untreated controls. Examination of immunoblots revealed anti-TDC reactive proteins in extracts from radicles of auxin-treated seedlings, but none in extracts from radicles of control seedlings. In contrast, TDC activity and immunoreactive protein levels in the aerial parts of controls and auxin-treated seedlings were comparable. Our results indicate that externally applied auxins induce both abnormal development and TDC activity in the radicles of Catharanthus seedlings. Although auxins slightly delayed the light-mediated induction of the cotyledon-specific last step in vindoline biosynthesis (i.e. acetylcoenzyme A: deacetylvindolin-O-acetyltransferase activity), seedlings still synthesized vindoline, one of the major alkaloid end products. Images Figure 2 PMID:16653009

  19. Ames Research Center views of Oats, Slash-Pine and Mung bean seedlings STS-3

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Young oat seedlings are shown in a ground laboratory after being flown into space aboard the Space Shuttle Columbia on STS-3 in March of 1982. All plants were part of the experimental Plant Growth Unit. They appear to have grown to look similar to the control seedlings on earth. A few small roots can be seen growing upward from the soil (33915); Young slash-pine seedlings are shown upon returning from the STS-3 mission (33916); Mung bean seedlings are shown after their return from space aboard the STS-3 (37917).

  20. Adventitious roots, leaf abscission and nutrient status of flooded Gmelina and Tectona seedlings.

    PubMed

    Osundina, M A; Osonubi, O

    1989-12-01

    When flooded, seedlings of Gmelina arborea Roxb. produced more adventitious roots, had lower foliar Mn concentrations and lost fewer leaves than seedlings of Tectona grandis L.f. Severing the adventitious roots produced by flooded Gmelina seedlings increased leaf Mn concentration and leaf abscission and reduced whole-plant dry matter production. Flooded Gmelina cuttings, which do not produce adventitious roots, abscised few leaves until foliar concentrations of Mn and Fe had risen substantially above those of unflooded cuttings, at which time most leaves were shed. The results indicate that the development of adventitious roots in flooded seedlings of Gmelina suppressed uptake of Mn thereby minimizing leaf abscission. PMID:14972970

  1. Community-wide spatial and temporal discordances of seed-seedling shadows in a tropical rainforest.

    PubMed

    Rother, Débora Cristina; Pizo, Marco Aurélio; Siqueira, Tadeu; Rodrigues, Ricardo Ribeiro; Jordano, Pedro

    2015-01-01

    Several factors decrease plant survival throughout their lifecycles. Among them, seed dispersal limitation may play a major role by resulting in highly aggregated (contagious) seed and seedling distributions entailing increased mortality. The arrival of seeds, furthermore, may not match suitable environments for seed survival and, consequently, for seedling establishment. In this study, we investigated spatio-temporal patterns of seed and seedling distribution in contrasting microhabitats (bamboo and non-bamboo stands) from the Brazilian Atlantic Forest. Spatial distribution patterns, spatial concordance between seed rain and seedling recruitment between subsequent years in two fruiting seasons (2004-2005 and 2007-2009), and the relation between seeds and seedlings with environmental factors were examined within a spatially-explicit framework. Density and species richness of both seeds and seedlings were randomly distributed in non-bamboo stands, but showed significant clustering in bamboo stands. Seed and seedling distributions showed across-year inconsistency, suggesting a marked spatial decoupling of the seed and seedling stages. Generalized linear mixed effects models indicated that only seed density and seed species richness differed between stand types while accounting for variation in soil characteristics. Our analyses provide evidence of marked recruitment limitation as a result of the interplay between biotic and abiotic factors. Because bamboo stands promote heterogeneity in the forest, they are important components of the landscape. However, at high densities, bamboos may limit recruitment for the plant community by imposing marked discordances of seed arrival and early seedling recruitment. PMID:25856393

  2. Monitoring Acacia seedlings establishment and survival for a geo-spatial analysis model

    NASA Astrophysics Data System (ADS)

    Isaacson, Sivan; Winters, Gidon; Blumberg, Dan G.; Rachmilevitch, shimon; Ephrath, Jhonathan E.

    2016-04-01

    Seedlings are considered the stage most vulnerable to environmental conditions in the life cycle of plants. For plants in general but even more so for desert plants, seedling survival during the first years is crucial to the longevity of the population. Within the study area, Arava valley, southern Israeli Negev desert, flood events have been known to induce germination of seedlings, with only a small percentage (if any) of such seedlings surviving the dry summer. Following the floods of the 2013 winter (Jan-April 2013), we identified a 50 x 50 m section within the Gidron Wadi (Ephemeral river), in which we located and marked some 50 acacia (Acacia tortilis and Acacia raddiana) seedlings. We monitored the seedlings survival, growth and trunk diameter over the period of three years as well as taking periodical thermal and near infra-red (NIR) photographs. In order to better understand the geohydrology conditions we created a digital elevation model of the Wadi segment that includes the seedlings location, using total station theodolite. The survey will enable us to locate and map hotspots in the Wadi, which have high potential for seedling establishment and survival. Understanding the conditions (micro-topographic, radiative, plant competition) effect on seedling germination and establishment, can be translated into a spatial rule set of recruitment probability for population dynamic spatial models.

  3. Piriformospora indica rescues growth diminution of rice seedlings during high salt stress

    PubMed Central

    Jogawat, Abhimanyu; Saha, Shreya; Bakshi, Madhunita; Dayaman, Vikram; Kumar, Manoj; Dua, Meenakshi; Varma, Ajit; Oelmüller, Ralf; Tuteja, Narendra; Johri, Atul Kumar

    2013-01-01

    Piriformospora indica association has been reported to increase biotic as well as abiotic stress tolerance of its host plants. We analyzed the beneficial effect of P. indica association on rice seedlings during high salt stress conditions (200 and 300 mM NaCl). The growth parameters of rice seedlings such as root and shoot lengths or fresh and dry weights were found to be enhanced in P. indica-inoculated rice seedlings as compared with non-inoculated control seedlings, irrespective of whether they are exposed to salt stress or not. However, salt-stressed seedlings performed much better in the presence of the fungus compared with non-inoculated control seedlings. The photosynthetic pigment content [chlorophyll (Chl) a, Chl b, and carotenoids] was significantly higher in P. indica-inoculated rice seedlings under high salt stress conditions as compared with salt-treated non-inoculated rice seedlings, in which these pigments were found to be decreased. Proline accumulation was also observed during P. indica colonization, which may help the inoculated plants to become salt tolerant. Taken together, P. indica rescues growth diminution of rice seedlings under salt stress.

  4. Effects of ectomycorrhizae removal on survival and growth of loblolly pine seedlings with pisolithus or natural ectomycorrhizae on an upland site in South Carolina. Progress report

    SciTech Connect

    Marx, D.H.

    1982-01-01

    This study was undertaken to ascertain the significance of mechanical loss of ectomycorrhizae formed by Pisolithus tinctorius or naturally occurring fungi encountered during lifting of nursery seedlings to the capacity of these seedlings to regenerate roots, survive, and grow. Seedlings were planted in January 1981. Seedlings with Pisolithus ectomycorrhizae formed in the nursery can tolerate more removal of ectomycorrhizae than routine nursery seedlings with natural ectomycorrhizae. However, seedlings in both ectomycorrhizal condition groups were severely impacted by removal of ectomycorrhizae. 1 table.

  5. 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.

  6. Fuel reduction at a Spanish heathland by prescribed fire and mechanical shredding: effects on seedling emergence.

    PubMed

    Fernández, Cristina; Vega, José A; Fonturbel, Teresa

    2013-11-15

    Traditional heathland burning has declined in Spain, leading to fuel accumulation and fuel reduction treatments have become common for severe wildfire hazard reduction. These methods need to maintain the botanical composition of those shrub communities. Prescribed fire has been widely used in the past, but we need to compare mechanical fuel reduction with prescribed fire because it is easier and safer to carry out in a wide range of weather conditions. This information could be particularly useful in flammable ecosystems all over the world where traditional anthropogenic burning has declined. In this study, we compared the effects of prescribed burning and mechanical shredding on the seedling emergence and its relation to the mature vegetation in a fire-prone heathland dominated by Erica australis L. and Pterospartum tridentatum (L.) Willk., in Galicia (NW Spain). We combined a greenhouse experiment with periodic field inventories of seedling emergence. In the greenhouse study, the seedling emergence was significantly higher in the soil samples after burning (383 seedlings m(-2)) than in samples before burning (242 seedlings m(-2)). In contrast, there was no significant difference in seedling density before and after mechanical shredding (243 compared with 261 seedlings m(-2)). Also, the number of seedlings that emerged after burning was significantly higher than that emerged after mechanical shredding. The maximum temperatures at the soil organic layer surface during burning were significantly and positively related to the density of Halimium lasianthum ssp. alyssoides and P. tridentatum seedlings. In the field study, the observed seedling density was very low both after prescribed burning and mechanical shredding. There was a high degree of similarity between emerged seedlings and mature vegetation in both the treated and in the untreated soils, which was probably a consequence of the dominance of resprouting species. Some consequences for the management of

  7. [Effects of sowing depth on seedling traits and root characteristics of summer maize].

    PubMed

    Cao, Hui-ying; Wang, Ding-bo; Shi, Jian-guo; Zhu, Kun-lun; Dong, Shu-ting; Liu, Peng; Zhao, Bin; Zhang, Ji-wang

    2015-08-01

    Two summer maize hybrids, Zhengdan 958 (ZD958) and Xianyu 335 (XY335), were used as experimental materials. 4 sowing depths (3, 5, 7 and 9 cm) and uneven sowing depth (CK) were designed under sand culture and field experiments to investigate the effects of sowing depth on seedling traits and root characteristics of summer maize. The results showed that the seedling emergence rate gradually decreased and seedling emergence time gradually lengthened as the sowing depth increased. Compared with the sowing depth of 3 cm, the seedling emergence rates of ZD958 and XY335 sown at the depth of 9 cm were reduced by 9.4% and 11.8%, respectively, and the seedling emergence duration was prolonged 1.5 d. With the increasing sowing depth, the seedling length and uniformity decreased significantly, the mesocotyl length increased significantly, while the coleoptile length had no significant difference; the primary radicle length gradually decreased, the total length of secondary radicle gradually increased, and the total root length had no significant difference; the total dry mass of seedling and mesocotyl increased significantly, and the total root dry mass had no significant difference. With the increasing sowing depth, the soluble sugar content in each part of seedling increased and the amount of nutritional consumption of germinating seeds increased, the seedling root growth rate increased, but the root activity decreased, and the number of total nodal root and nodal layers increased. With the increasing sowing depth, harvested ears per unit area were reduced by decreased seedling emergence rate and seedling vigor, thus influenced the yield. In addition, uniform sowing depth could improve the canopy uniformity and relative characteristics, then increase the yield. PMID:26685603

  8. Physiological effects of NaCl on Apocynum venetum seedlings

    NASA Astrophysics Data System (ADS)

    Han, Wei; Cao, Ling

    2016-04-01

    The physiological effects of NaCl on the Apocynum venetum seedlings were investigated, including the chlorophyll a fluorescence, leaf potential and growth rate, etc. The findings indicated that along with hardness index increasing, the leaf sample's chlorophyll content assumed the fluctuation condition which dropped firstly elevated again; the leaf water potential maintained stable basically; the energy of light absorption, the assignment and the dissipation balanced at 10 g/L and the growth rate presented the maximum value 9.8 mm/d; Along with the stress extension, the greatest quantum yield Fv/Fm dropped, metallic ion's absorption increased. In the 21st day, non-photochemical quenching coefficient NPQ presented the maximum value, absorbed energy proportion parameter Y(II) dropped firstly restored again, 3 kind of energy absorptions, the assignment dissipation parameter proportion stabilized in 10 g/L at Y(II):Y(NO):Y(NPQ) = 65%:20%:15%.The results suggested that in the A. venetum nursery process in the southern edge of Taklimakan Desert, phased tending should be adopted according to the seedling stage: 5-10 g/L salinity water should be used in irrigation in the seedling stage to maintain a more high leaf water potential which could prevent the decomposition of chlorophyll in which higher proportion of photochemical energy conversion could be stable using 10 g/L salt water irrigation to give A. venetum a full play of stronger salt adaptability to the southern margin of the Taklimakan Desert Oasis-Desert Ecotone in its restoration and construction. Key words: saline water irrigation; leaf water potential; energy allocation strategies; growth rate

  9. Genetic regulation and photocontrol of anthocyanin accumulation in maize seedlings.

    PubMed Central

    Taylor, L P; Briggs, W R

    1990-01-01

    The flavonoid pathway leading to anthocyanin biosynthesis in maize is controlled by multiple regulatory genes and induced by various developmental and environmental factors. We have investigated the effect of the regulatory loci R, B, and Pl on anthocyanin accumulation and on the expression of four genes (C2, A1, Bz1, and Bz2) in the biosynthetic pathway during an inductive light treatment. The results show that light-mediated anthocyanin biosynthesis is regulated solely by R; the contributions of B and Pl are negligible in young seedlings. Induction of the A1 and Bz2 genes by high fluence-rate white light requires the expression of a dominant R allele, whereas accumulation of C2 and Bz1 mRNA occurs with either a dominant or recessive allele at R. A1 and Bz2 mRNA accumulate only in response to high fluence-rate white light, but Bz1 is fully expressed in dim red light. Some C2 mRNA is induced by dim red light, but accumulation is far greater in high fluence-rate white light. Furthermore, expression from both dominant and recessive alleles of the regulatory gene R is enhanced by high fluence-rate white light. Seedlings with a recessive allele at R produce functional chalcone synthase protein (the C2 gene product) but accumulate no anthocyanins, suggesting that, in contrast to the R-mediated coordinate regulation of C2 and Bz1 observed in the aleurone, C2 expression in seedlings is independent of R and appears to be regulated by a different light-sensitive pathway. PMID:2136630

  10. Drought-Induced Leaf Proteome Changes in Switchgrass Seedlings

    PubMed Central

    Ye, Zhujia; Sangireddy, Sasikiran; Okekeogbu, Ikenna; Zhou, Suping; Yu, Chih-Li; Hui, Dafeng; Howe, Kevin J.; Fish, Tara; Thannhauser, Theodore W.

    2016-01-01

    Switchgrass (Panicum virgatum) is a perennial crop producing deep roots and thus highly tolerant to soil water deficit conditions. However, seedling establishment in the field is very susceptible to prolonged and periodic drought stress. In this study, a “sandwich” system simulating a gradual water deletion process was developed. Switchgrass seedlings were subjected to a 20-day gradual drought treatment process when soil water tension was increased to 0.05 MPa (moderate drought stress) and leaf physiological properties had expressed significant alteration. Drought-induced changes in leaf proteomes were identified using the isobaric tags for relative and absolute quantitation (iTRAQ) labeling method followed by nano-scale liquid chromatography mass spectrometry (nano-LC-MS/MS) analysis. Additionally, total leaf proteins were processed using a combinatorial library of peptide ligands to enrich for lower abundance proteins. Both total proteins and those enriched samples were analyzed to increase the coverage of the quantitative proteomics analysis. A total of 7006 leaf proteins were identified, and 257 (4% of the leaf proteome) expressed a significant difference (p < 0.05, fold change <0.6 or >1.7) from the non-treated control to drought-treated conditions. These proteins are involved in the regulation of transcription and translation, cell division, cell wall modification, phyto-hormone metabolism and signaling transduction pathways, and metabolic pathways of carbohydrates, amino acids, and fatty acids. A scheme of abscisic acid (ABA)-biosynthesis and ABA responsive signal transduction pathway was reconstructed using these drought-induced significant proteins, showing systemic regulation at protein level to deploy the respective mechanism. Results from this study, in addition to revealing molecular responses to drought stress, provide a large number of proteins (candidate genes) that can be employed to improve switchgrass seedling growth and establishment under

  11. Drought-Induced Leaf Proteome Changes in Switchgrass Seedlings.

    PubMed

    Ye, Zhujia; Sangireddy, Sasikiran; Okekeogbu, Ikenna; Zhou, Suping; Yu, Chih-Li; Hui, Dafeng; Howe, Kevin J; Fish, Tara; Thannhauser, Theodore W

    2016-01-01

    Switchgrass (Panicum virgatum) is a perennial crop producing deep roots and thus highly tolerant to soil water deficit conditions. However, seedling establishment in the field is very susceptible to prolonged and periodic drought stress. In this study, a "sandwich" system simulating a gradual water deletion process was developed. Switchgrass seedlings were subjected to a 20-day gradual drought treatment process when soil water tension was increased to 0.05 MPa (moderate drought stress) and leaf physiological properties had expressed significant alteration. Drought-induced changes in leaf proteomes were identified using the isobaric tags for relative and absolute quantitation (iTRAQ) labeling method followed by nano-scale liquid chromatography mass spectrometry (nano-LC-MS/MS) analysis. Additionally, total leaf proteins were processed using a combinatorial library of peptide ligands to enrich for lower abundance proteins. Both total proteins and those enriched samples were analyzed to increase the coverage of the quantitative proteomics analysis. A total of 7006 leaf proteins were identified, and 257 (4% of the leaf proteome) expressed a significant difference (p < 0.05, fold change <0.6 or >1.7) from the non-treated control to drought-treated conditions. These proteins are involved in the regulation of transcription and translation, cell division, cell wall modification, phyto-hormone metabolism and signaling transduction pathways, and metabolic pathways of carbohydrates, amino acids, and fatty acids. A scheme of abscisic acid (ABA)-biosynthesis and ABA responsive signal transduction pathway was reconstructed using these drought-induced significant proteins, showing systemic regulation at protein level to deploy the respective mechanism. Results from this study, in addition to revealing molecular responses to drought stress, provide a large number of proteins (candidate genes) that can be employed to improve switchgrass seedling growth and establishment under soil

  12. Enhancing seedling production of native species to restore gypsum habitats.

    PubMed

    Cañadas, E M; Ballesteros, M; Foronda, A; Navarro, F B; Jiménez, M N; Lorite, J

    2015-11-01

    Gypsum habitats are widespread globally and are important for biological conservation. Nevertheless, they are often affected by human disturbances and thus require restoration. Sowing and planting have shown positive results, but these actions are usually limited by the lack of native plant material in commercial nurseries, and very little information is available on the propagation of these species. We address this issue from the hypothesis that gypsum added to a standard nursery growing medium (peat) can improve seedling performance of gypsum species and, therefore, optimise the seedling production for outplanting purposes. We test the effect of gypsum on emergence, survival, and growth of nine native plant species, including gypsophiles (exclusive to gypsum) and gypsovags (non-exclusive to gypsum). We used four treatments according to the proportions, in weight, of gypsum:standard peat (G:S), i.e. high-g (50G:50S), medium-g (25G:75S), low-g (10G:90S), and standard-p (0G:100S). Our results showed that the gypsum treatments especially benefited the emergence stage, gypsophiles as group, and Ononis tridentata as a taxon. In particular, the gypsum treatments enhanced emergence of seven species, survival of three species, and growth of two gypsophiles, while the use of the standard peat favoured only the emergence or growth of three gypsovags. Improving emergence and survival at the nursery can provide a reduction of costs associated with seed harvesting, watering, and space, while enlarging seedlings can favour the establishment of individuals after outplanting. Thus, we suggest adding gypsum to standard peat for propagating seedlings in species from gypsum habitats, thereby potentially cutting the costs of restoring such habitats. Our assessment enables us to provide particular advice by species. In general, we recommend using between 25 and 50% of gypsum to propagate gypsophiles, and between 0 and 10% for gypsovags. The results can benefit not only the production

  13. A Chemical Genetic Screening Procedure for Arabidopsis thaliana Seedlings

    PubMed Central

    Bjornson, Marta; Song, Xingshun; Dandekar, Abhaya; Franz, Annaliese; Drakakaki, Georgia; Dehesh, Katayoon

    2016-01-01

    Unbiased screening approaches are powerful tools enabling identification of novel players in biological processes. Chemical genetic screening refers to the technique of using a reporter response, such as expression of luciferase driven by a promoter of interest, to discover small molecules that affect a given process when applied to plants. These chemicals then act as tools for identification of regulatory components that could not otherwise be detected by forward genetic screens due to gene family redundancy or mutant lethality. This protocol describes a chemical genetic screen using Arabidopsis thaliana seedlings, which has led to recognition of novel players in the plant general stress response.

  14. 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. PMID:24943713

  15. 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

  16. Effects of resource availability on seedling recruitment in a fire-maintained savanna.

    PubMed

    Iacona, Gwenllian D; Kirkman, L Katherine; Bruna, Emilio M

    2010-05-01

    The herbaceous ground cover of the longleaf pine ecosystem harbors the highest plant species richness in North America, with up to 50 species per square meter, but the mechanisms that regulate this diversity are not well understood. In this system, variability in seedling recruitment events may best explain the extremely high small-scale species richness and its relationship to soil moisture and system net primary productivity. To understand the potential mechanistic controls on species richness, we used a long-term resource manipulation study across a natural soil moisture gradient to assess environmental controls on seedling recruitment. We considered the availability of resources to be an indicator of seedling safe-site supply, and also manipulated seed availability to examine the relative importance of recruitment limitations on seedling diversity. We found that water availability regulated the number of species in the seedling community regardless of the underlying natural moisture gradient, and that this effect may result from differential responses of seedling guilds to resource availability. Water supply was more important than seed supply in determining seedling establishment, suggesting that appropriate sites for regeneration are a factor limiting seedling success. This is the first study that shows that the episodic supply of microsites for recruitment could influence species richness in the highly threatened and biodiverse longleaf pine savanna. PMID:19921271

  17. Characterization of Rhizoctonia isolates associated with damping-off and crown rot of rooibos seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rhizoctonia species were reported to be an important component of the complex involved in damping-off of rooibos (Aspalathus linearis) seedlings and cause severe crown rot of seedlings in nurseries. However, no information is available on the anastomosis groups (AGs) of Rhizoctonia associated with d...

  18. FOLIAR N RESPONSE OF PONDEROSA PINE SEEDLINGS TO ELEVATED CO2 AND O3

    EPA Science Inventory

    Interactions between needle N status and exposure to combined CO2 and O3 stresses were studied in Pinus ponderosa seedlings. The seedlings were grown for three years (April 1998 through March 2001) in outdoor chambers in native soils from eastern Oregon, and exposed to ambient ...

  19. Determining Critical Phosphorus Levels for Cool Season Seedlings Established on Calcareous Soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sufficient soil phosphorus (P) is critical for rapid seedling establishment. P-deficient seedlings lack vigor and form low density turf areas which are more susceptible to soil erosion and nutrient loss. A greenhouse study was conducted to determine the critical soil P-levels necessary to establish ...

  20. Evaluation of rice seedling tolerance to constant and intermittent low temperature stress

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low temperatures generally slow or halt the growth of rice seedlings and may result in various injuries and mortality depending on the length and severity of the cold stress. Seedling cold tolerance is complex and many quantitative trait loci (QTLs) have been identified using different conditions an...

  1. Wheat Seedlings as Food Supplement to Combat Free Radicals: An In Vitro Approach

    PubMed Central

    Ravikumar, P.; Shalini, G.; Jeyam, M.

    2015-01-01

    The present study was designed to evaluate the antioxidant activity of 5 organic solvent extracts (petroleum ether, n-hexane, chloroform, ethyl acetate and methanol) of wheat grains, 3, 5 and 7 days old wheat seedlings. To determine the antioxidant activity of five extracts of four different samples, 1,1-diphenyl-2-picrylhydrazyl and 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity, total phenolic content and ferrous reducing power ability were carried out. 1,1-Diphenyl-2-picrylhydrazyl radical scavenging effect of chloroform and ethyl acetate extracts of 3 days old wheat seedlings was higher than wheat grains. Chloroform, ethyl acetate and methanol extracts of 3 days old wheat seedlings exhibited higher 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging effcet than extracts of other samples. The phenolic content was high in chloroform, ethyl acetate and methanol extract of 5 days old wheat seedlings. When compared with wheat grain, reducing power ability was high in chloroform, ethyl acetate and methanol extract of wheat seedlings, especially in 3 and 5 days old wheat seedlings. From the above results, it was concluded that chloroform, ethyl acetate and methanol extract of 3, 5 and 7 days old wheat seedlings showed better antioxidant activity than the wheat grain extracts. Hence, the results of the present study suggest the intake of wheat seedlings as a food supplement to combat the diseases caused by free radicals. PMID:26798175

  2. Maize white seedling 3 results from disruption of homogentisate solanesyl transferase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize white seedling 3 (w3) has served as a model albino-seedling mutant since its discovery in 1923. We show here that the w3 phenotype is caused by disruptions in homogentisate solanesyl transferase (HST), an enzyme that catalyzes the committed step in plastoquinone-9 (PQ9) biosynthesis. This re...

  3. CROWN GALL INCIDENCE: SEEDLING PARADOX WALNUT ROOTSTOCK VERSUS OWN-ROOTED ENGLISH WALNUT TREES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seedling Paradox (Juglans hindsii x J. regia) has been the rootstock of choice for English walnut in California because of its vigor and greater tolerance of wet soil conditions. However, seedling Paradox rootstock is highly susceptible to crown gall, a disease caused by the soil-borne bacterium Agr...

  4. Energy biomass tree seedling production study. Fuels from woody biomass. Progress report, September 1978-January 1980

    SciTech Connect

    Foote, K.R.

    1980-03-01

    The research to date has centered around the establishment of baseline growing conditions for a number of species of tree seedlings, primarily deciduous hardwoods. As these baseline conditions were established for each specie, the shoot and root environments were manipulated in an attempt to establish techniques to increase seedling growth and reduce production times. Seedlings were outplanted in an attempt to establish baseline survival rates for seedlings grown in totally controlled environments. Studies to determine the optimum container for tree seedling production have been run and will continue as other containers are identified and made available. The most significant of the research results has been in the maximization of seedling growth. Seedling production times have been decreased in some species by as much as 50% under the baseline production times. Controlled environment production techniques provide for plant densities as high as 144 seedlings per square foot of growing space. Investigations of growing media indicate a significant species specific responses. Preliminary results of outplanting indicate survival rates as high as 90% plus.

  5. Environmental factors and seed abundance influence seedling emergence of a perennial forest herb

    NASA Astrophysics Data System (ADS)

    Kolb, Annette; Barsch, Katharina

    2010-09-01

    Seedlings are an important, but vulnerable stage in the life cycle of plants. The identification of factors affecting their recruitment is therefore fundamental for understanding basic plant population processes as well as plant distribution and abundance. In this study, we used a combined experimental and observational approach to examine how microsite quality and quantity as well as seed supply affect different processes of seedling establishment, using the perennial forest herb Phyteuma spicatum (Campanulaceae) as model species. This species reproduces exclusively by seed, and seedling emergence, growth and survival are therefore critical stages in its life cycle. Seedlings were frequent in microsites with bare soil and overall high light intensities, and were less common in sites with deep litter layers as well as dense and low vegetation. Seed addition, via experimental sowings or via the natural seed rain, consistently enhanced seedling emergence. Seed density effects, however, were variable among years; seedling emergence rates decreased at high seed densities in one of two seed cohorts. Seedling emergence time, size and survival were largely not affected by microhabitat type or seed density. In summary, our findings suggest that environmental factors and seed abundance determine recruitment success of P. spicatum and that effects on early processes of seedling establishment (emergence) are stronger than effects on late processes of establishment (growth and survival). Our work thereby contributes to a better understanding of the mechanisms underlying recruitment patterns of this species and other perennial herbs.

  6. Cotton Seedling Injury and Recovery from Wind Blown Sand Abrasion: I. Duration of Exposure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of acres of crops are exposed to wind blown sand abrasion injury each year and in many instances the damage is thought to be sufficiently severe to require replanting. The goal of this study was to determine the effects of wind blown sand abrasion duration on cotton seedlings. Seedlings of...

  7. Effects of seed-caching desert rodents on seedling survival of Indian ricegrass (Achnatherum hymenoides)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In addition to consuming seeds, many small mammals also cache seeds in shallowly buried scatterhoards, and seeds of many plant species germinate and establish aggregated clusters of seedlings from these caches. Scatterhoards made by desert heteromyid rodents provide the primary source of seedling re...

  8. ANATOMY OF THE SEED AND SEEDLING OF SPARTINA ALTERNIFLORA LOIS (POACEAE)

    EPA Science Inventory

    Members of the genus Spartina are dominant macrophytes in many salt marshes of North and South America, Europe, and Africa. Although the genus is of great ecological importance, seeds and seedlings of its 16 species have not been described. he seed and seedling of an American spe...

  9. Young restored forests increase seedling recruitment in abandoned pastures in the Southern Atlantic rainforest.

    PubMed

    Leitão, Flora H M; Marques, Marcia C M; Ceccon, Eliane

    2010-12-01

    Planting seedlings is a common technique for abandoned pastures restoration in the tropics, supposedly by increasing the seedling recruitment and accelerating succession. In this study we evaluated the role of a young restored forest (one year old) in enhancing seedling establishment from two sources (seed rain and seed bank), in the Atlantic Rainforest region in Southern Brazil. We compared abandoned pasture, young restored forest and old-growth forest with respect to the seedlings recruited from different sources, by monitoring 40 permanent plots (0.5 m x 0.5 m) over 20 months. From the three studied areas a total of 392 seedlings of 53 species were recruited. Species were mainly herbaceous (85%), pioneers (88%), zoochorous (51%) and small-seeded species (60%). Seedling recruitment from the seed bank (density and species richness) was higher and dominated by herbaceous species in the abandoned pasture and in the young restored forest; on the other hand, the recruitment of woody species from seed rain was more pronounced in the old-growth forest. The young restored forest increased the species richness of woody seedlings recruitment from the seed bank (two-fold) and from seed rain (three-fold) compared to the abandoned pasture. Also, the seedling density in young restored forest was still higher than abandoned pastures (seed bank: four times; seed rain: ten times). Our results show that even young restored areas enhance the establishment of woody species and should be considered an important step for pasture restoration. PMID:21246991

  10. Germination, survival, and growth of grass and forb seedlings: effects of soil moisture variability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seed germination and seedling growth, survivorship, and final biomass and their responses to varying numbers of days between watering were studied in two grass and six forb species native to the U.S. Central Plains grasslands. Our object was to assess the potential role of germination and seedling g...

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

    PubMed

    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

  12. Comparative transcription profiling analyses of maize reveals candidate defensive genes for seedling resistance against corn earworm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As maize seedlings germinate into the soil, they encounter an environment teaming with insects seeking rich sources of nutrition. Maize presumably has developed a number of molecular mechanisms to ensure survival at the beginning of its life cycle. Bioassays indicated maize seedlings were more toxic...

  13. 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

  14. Seed and seedling ecology research as the foundation for enhancing restoration outcomes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The success of restoration in arid and semiarid rangelands is severely limited by deficiencies in our understanding of seedling ecology and seedling recruitment. This is significant because rangelands provide sustenance for roughly one-third of the global population, and evolving challenges such as...

  15. Defoliation by pastoralists affects savanna tree seedling dynamics by limiting the facilitative role of canopy cover.

    PubMed

    Bufford, Jennifer L; Gaoue, Orou G

    2015-07-01

    Recurrent tree defoliation by pastoralists, akin to herbivory, can negatively affect plant reproduction and population dynamics. However, our understanding of the indirect role of defoliation in seedling recruitment and tree-grass dynamics in tropical savanna is limited. In West African savanna, Fulani pastoralists frequently defoliate several fodder tree species to feed livestock in the dry season. We investigated the direct and indirect effects of recurrent defoliation of African mahogany (Khaya senegalensis) by Fulani people on seedling (< 2 cm basal diameter) and sapling dynamics in West Africa using four years of demographic data on seedling and sapling density, growth, and survival, coupled with fruit production and microhabitat data over the same time period. Tree canopy cover facilitated seedlings but had negative effects on sapling growth possibly via intraspecific competition with adult plants. Interspecific competition with grasses strongly reduced seedling survival but had a weak effect on sapling growth. Fire reduced seedling survival and weakly reduced growth of seedlings and saplings, but did not affect sapling survival. These results indicate that the effect of fire on seedlings and saplings is distinct, a mechanism suitable for an episodic recruitment of seedlings into the sapling stage and consistent with predictions from the demographic bottleneck model. Defoliation affected seedling density and sapling growth through changes in canopy cover, but had no effect on seedling growth and sapling survival. In the moist region, sapling density was higher in sites with low-intensity defoliation, indicating that defoliation may strengthen the tree recruitment bottleneck. Our study suggests that large-scale defoliation can alter the facilitative role of nurse trees on seedling dynamics and tree-sapling competition. Given that tree defoliation by local people is a widespread activity throughout savanna-forest systems in West Africa, it has the potential to

  16. Cryptic coloration of Macaranga bancana seedlings: A unique strategy for a pioneer species.

    PubMed

    Fadzly, Nik; Zuharah, Wan Fatma; Mansor, Asyraf; Zakaria, Rahmad

    2016-07-01

    Macaranga bancana is considered as a successful pioneer plant species. Usually found in disturbed and open areas, most of the current research focused on its relations with ants. One of the unique feature of the plants is that the seedling leaves are red, resembling and almost matching the background. Using a portable spectrometer, we measured the color reflectance of M. bancana seedlings (less than 20 cm in height). We also measured the leaf litter reflectance, adult M. bancana leaves and also seedlings of several other species found in the vicinity of M. bancana seedlings. The reflectances of M. bancana seedlings are very similar to that of the leaf litter background. We suggest that this cryptic coloration is crucial during the early stages of the plant when it still cannot rely on the protection of ants. PMID:27315145

  17. Forty years of inoculating seedlings with truffle fungi: past and future perspectives.

    PubMed

    Murat, Claude

    2015-01-01

    The first commercialization of seedlings inoculated with truffle fungi occurred in 1973. Over the last 40 years, considerable progress has been made relative to quality control for inoculated seedlings. A recently published paper by Andrés-Alpuente and colleagues (Mycorrhiza 24:29-37, 2014) reviewed and tested the different methods of mycorrhization assessment currently used in Europe. The aim of this paper is to augment their findings by adding information to the discussion about the most important steps in seedling quality control. Additionally, the history of seedlings inoculated with truffles, procedures currently used in France for seedling control quality, and a reflection on future research aimed at increasing truffle production will be presented. PMID:24989673

  18. Sucrose Represses the Developmentally Controlled Transient Activation of the Plastocyanin Gene in Arabidopsis thaliana Seedlings.

    PubMed Central

    Dijkwel, P. P.; Kock, PAM.; Bezemer, R.; Weisbeek, P. J.; Smeekens, SCM.

    1996-01-01

    The plastocyanin (PC) gene of Arabidopsis thaliana is activated independently of light during early seedling development. In etiolated seedlings, PC mRNA levels increase transiently and a maximum dark level is reached after 2 d of growth in darkness. In etiolated transgenic seedlings carrying a chimeric PC-promoter: luciferase fusion gene, luciferase activity is similarly increased after 2 d of growth. The transient increase in PC mRNA and luciferase activity levels can be repressed by sucrose. Nonmetabolizable sugars and polyethylene glycol do not have a major effect on PC gene expression. Also, light-grown seedlings show a similar transient and sucrose-sensitive increase in PC mRNA levels and luciferase activity, as in dark-grown seedlings, but here expression levels are 15- fold higher. These findings suggest the presence of a sucrose-sensitive, developmentally controlled expression mechanism that operates independently of light. PMID:12226197

  19. Effects of Kinetin, IAA, and Gibberellin on Ethylene Production, and Their Interactions in Growth of Seedlings.

    PubMed

    Fuchs, Y; Lieberman, M

    1968-12-01

    Kinetin in concentrations of 10(-8) to 10(-4)m, stimulated ethylene production in 3 and 4-day old etiolated seedlings of Alaska pea (Pisum sativum L. var. Alaska). Seedlings of other species responded similarly. The response to kinetin depended on the age of the seedlings.Kinetin alone did not influence ethylene production in 6-day old stem sections, but it greatly increased the enhancing effect of IAA.Gibberellic acid had no effect on ethylene production by pea seedlings during the first 6 days of growth. Ethylene and gibberellic acid are antagonistic in their effects on growth of the seedlings; ethylene interfered severely with the action of gibberellic acid but did not completely suppress it.The inhibitors cycloheximide, cupferron, and N-ethylmaleimide, caused considerable inhibition of kinetin-induced ethylene production but were much less effective in the endogenous ethylene-forming system. PMID:16657004

  20. Tension wood fibers are related to gravitropic movement of red mangrove (Rhizophora mangle) seedlings.

    PubMed

    Fisher, Jack B; Tomlinson, P Barry

    2002-02-01

    Freshly collected viviparous seedlings (propagules) were collected from wild plants of Rhizophora mangle and planted in vertical or horizontal positions. A total of 80 seedlings were examined anatomically at various ages and orientations. After rooting, seedlings reoriented from horizontal to vertical by extreme bending in the hook region of the hypocotyl directly above the basal 1 cm where roots formed. Hypocotyl bending occurred over many months. Trends in position and relative abundance of tension fibers (also called gelatinous fibers) over time were followed. The erection of the seedling was related to increased secondary xylem and the number of tension wood fibers on the upper side of the hook region. However, linear regressions had low coefficient of determination (r(2)) values, presumably related to seedlings with high variability. PMID:12884047

  1. Watermelon seedling growth and mortality as affected by Anasa tristis (Heteroptera: Coreidae).

    PubMed

    Edelson, J V; Duthie, J; Roberts, W

    2002-06-01

    Adult squash bugs, Anasa tristis (De Geer), were confined on seedling watermelon plants at densities of zero, one, two, and four per plant. Squash bugs were allowed to feed on the plants until plants died or reached 30 cm in height. Number of leaves and length of plant vine were recorded at 2- or 3-d intervals. Seedling foliage, stems, and roots were harvested and dried after plants reached 30 cm in height. Growth of seedlings was regressed on number of squash bugs and results indicated that an increasing density of squash bugs feeding on seedlings resulted in a significant reduction in plant growth. Additionally, increased density of squash bugs resulted in reduced weight of foliage and root dry biomass. Seedling mortality increased as the density of squash bugs increased. PMID:12076005

  2. Root dipping of conifer seedlings shows little benefit in the northern Rocky Mountains. Forest Service research paper

    SciTech Connect

    Sloan, J.P.

    1994-07-01

    In the growth chamber, in the greenhouse, and in field studies, root dipping of bareroot lodgepole pine, ponderosa pine, Douglas-fir, and Engelmann spruce seedlings did not improve seedling survival, shoot growth, or root growth under dry soil conditions. Seedling root growth varied with tree species, soil type, and type of rood dip.

  3. Identification of Calonectria colhounii Associated with Basal Stem Rot on Blueberry Seedlings Imported from the United States of America

    PubMed Central

    Jeon, Nak Beom; Kim, Wan Gyu; Park, Myung Soo; Hyun, Ik-Hwa; Heo, Noh-Youl

    2010-01-01

    Basal stem rot symptoms were found on blueberry seedlings imported from the United States of America in 2008. The fungus obtained from the diseased seedlings was identified as Calonectria colhounii based on morphological and molecular characteristics. The consignments of the blueberry seedlings infected with C. colhounii were destroyed to prevent introduction of the fungus to Korea. PMID:23956678

  4. Enrichment and Analysis of Intact Phosphoproteins in Arabidopsis Seedlings

    PubMed Central

    Aryal, Uma K.; Ross, Andrew R. S.; Krochko, Joan E.

    2015-01-01

    Protein phosphorylation regulates diverse cellular functions and plays a key role in the early development of plants. To complement and expand upon previous investigations of protein phosphorylation in Arabidopsis seedlings we used an alternative approach that combines protein extraction under non-denaturing conditions with immobilized metal-ion affinity chromatography (IMAC) enrichment of intact phosphoproteins in Rubisco-depleted extracts, followed by identification using two-dimensional gel electrophoresis (2-DE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). In-gel trypsin digestion and analysis of selected gel spots identified 144 phosphorylated peptides and residues, of which only18 phosphopeptides and 8 phosphosites were found in the PhosPhAt 4.0 and P3DB Arabidopsis thaliana phosphorylation site databases. More than half of the 82 identified phosphoproteins were involved in carbohydrate metabolism, photosynthesis/respiration or oxidative stress response mechanisms. Enrichment of intact phosphoproteins prior to 2-DE and LC-MS/MS appears to enhance detection of phosphorylated threonine and tyrosine residues compared with methods that utilize peptide-level enrichment, suggesting that the two approaches are somewhat complementary in terms of phosphorylation site coverage. Comparing results for young seedlings with those obtained previously for mature Arabidopsis leaves identified five proteins that are differentially phosphorylated in these tissues, demonstrating the potential of this technique for investigating the dynamics of protein phosphorylation during plant development. PMID:26158488

  5. Mexican propolis flavonoids affect photosynthesis and seedling growth.

    PubMed

    King-Díaz, Beatriz; Granados-Pineda, Jessica; Bah, Mustapha; Rivero-Cruz, J Fausto; Lotina-Hennsen, Blas

    2015-10-01

    As a continuous effort to find new natural products with potential herbicide activity, flavonoids acacetin (1), chrysin (2) and 4',7-dimethylnarangenin (3) were isolated from a propolis sample collected in the rural area of Mexico City and their effects on the photosynthesis light reactions and on the growth of Lolium perenne, Echinochloa crus-galli and Physalis ixocarpa seedlings were investigated. Acacetin (1) acted as an uncoupler by enhancing the electron transport under basal and phosphorylating conditions and the Mg(2+)-ATPase. Chrysin (2) at low concentrations behaved as an uncoupler and at concentrations up to 100 μM its behavior was as a Hill reaction inhibitor. Finally, 4',7-dimethylnarangenin (3) in a concentration-dependent manner behaved as a Hill reaction inhibitor. Flavonoids 2 and 3 inhibited the uncoupled photosystem II reaction measured from water to 2,5-dichloro-1,4-benzoquinone (DCBQ), and they did not inhibit the uncoupled partial reactions measured from water to sodium silicomolybdate (SiMo) and from diphenylcarbazide (DPC) to diclorophenol indophenol (DCPIP). These results indicated that chrysin and 4',7-dimethylnarangenin inhibited the acceptor side of PS II. The results were corroborated with fluorescence of chlorophyll a measurements. Flavonoids also showed activity on the growth of seedlings of Lolium perenne and Echinochloa crus-galli. PMID:26318278

  6. Proteomics analysis of compatibility and incompatibility in grafted cucumber seedlings.

    PubMed

    Xu, Qing; Guo, Shi-Rong; Li, Lin; An, Ya-Hong; Shu, Sheng; Sun, Jin

    2016-08-01

    Graft compatibility between rootstock and scion is the most important factor influencing the survival of grafted plants. In this study, we used two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF/TOF MS) to investigate differences in leaf proteomes of graft-compatible and graft-incompatible cucumber (Cucumis sativus L.)/pumpkin (Cucurbita L.) combinations. Cucumber seedlings were used as the scions and two pumpkin cultivars with strongly contrasting grafting compatibilities were used as the rootstocks. Non-grafted and self-grafted cucumber seedlings served as control groups. An average of approximately 500 detectable spots were observed on each 2-DE gel. A total of 50 proteins were differentially expressed in response to self-grafting, compatible-rootstock grafting, and incompatible-rootstock grafting and were all successfully identified by MALDI-TOF/TOF MS. The regulation of Calvin cycle, photosynthetic apparatus, glycolytic pathway, energy metabolism, protein biosynthesis and degradation, and reactive oxygen metabolism will probably contribute to intensify the biomass and photosynthetic capacity in graft-compatible combinations. The improved physiological and growth characteristics of compatible-rootstock grafting plants are the result of the higher expressions of proteins involved in photosynthesis, carbohydrate and energy metabolism, and protein metabolism. At the same time, the compatible-rootstock grafting regulation of stress defense, amino acid metabolism, and other metabolic functions also plays important roles in improvement of plant growth. PMID:27070289

  7. Some Factors Regulating Auxin Translocation in Intact Bean Seedlings 1

    PubMed Central

    Long, John; Basler, Eddie

    1973-01-01

    Several factors which influence the translocation patterns of stem-injected indoleacetic acid, 2,4-dichlorophenoxyacetic acid, and 2,4,5-trichlorophenoxyacetic acid in bean seedlings (Phaseolus vulgaris L. cv. Stringless Greenpod) were characterized. The acropetal translocation of auxin from the site of injection is markedly sensitive to concentration in the range of 1.0 to 5.0 micrograms per plant. The antiauxin p-chlorophenoxyisobutyric acid enhanced translocation of 2,4,5-trichlorophenoxyacetic acid to the growing shoots and primary leaves. Translocation to the roots was unaffected by p-chlorophenoxyisobutyric acid while leaching of 2,4,5-trichlorophenoxyacetic acid into the nutrient solution was enhanced slightly. Steam girdling experiments revealed that translocation to the primary leaves was in the xylem. The protein synthesis inhibitor, cycloheximide, inhibited accumulation of 2,4,5-trichlorophenoxyacetic acid in young shoots, epicotyls, and roots and enhanced accumulation in the primary leaves. The relative exchangeability of auxin between xylem and phloem is discussed in terms of regulation of auxin movements in intact bean seedlings. Images PMID:16658273

  8. Arsenic toxicity in soybean seedlings and their attenuation mechanisms.

    PubMed

    Armendariz, Ana L; Talano, Melina A; Travaglia, Claudia; Reinoso, Herminda; Wevar Oller, Ana L; Agostini, Elizabeth

    2016-01-01

    Even though vast areas contaminated with arsenic (As) are under soybean (Glycine max) cultivation, little is known about the growth and intrinsic antioxidant metabolism of soybean in response to As exposure. Thus, an evaluation was carried out of plant growth, root anatomy, antioxidant system and photosynthetic pigment content under arsenate (As(V)) and arsenite (As(III)) treatment. Soybean seedling growth was significantly affected at 25 μM or higher concentrations of As(V) or As(III), and the toxic effect on root growth was associated with cell death of root tips. Microscopic analysis of cross-sections of As-treated root showed a reduction in the cortex area, dark deposits in cortex cells and broken cells in the outer layer. Similarly, in the vascular cylinder, dark deposits within xylem vessel elements and phloem cell walls were observed. In all the analyzed parameters, the deleterious effect was more evident under As(III) than As(V) treatment. Arsenic-treated soybean seedlings showed increased activity of antioxidant enzymes [total peroxidases (Px) and superoxide dismutase (SOD)] in root and shoot harvested after 2 and 5 d of treatment. However, a reduction in chlorophyll content and an increase in membrane lipids peroxidation were observed. It is suggested that root structural alterations induced by As, such as the particular pattern of dark depositions in the vascular system, could be associated with an adaptation or detoxification mechanism to prevent As translocation to the aboveground tissues. PMID:26686284

  9. Fungal communities influence root exudation rates in pine seedlings.

    PubMed

    Meier, Ina C; Avis, Peter G; Phillips, Richard P

    2013-03-01

    Root exudates are hypothesized to play a central role in belowground food webs, nutrient turnover, and soil C dynamics in forests, but little is known about the extent to which root-associated microbial communities influence exudation rates in trees. We used a novel experimental technique to inoculate loblolly pine (Pinus taeda L.) seedlings with indigenous forest fungi to examine how diverse fungal communities influence exudation. Surface-sterilized seeds were sown in intact, unsieved soil cores for 14 weeks to promote root colonization by fungi. After 14 weeks, we transferred seedlings and root-associated fungi into cuvettes and measured exudate accumulation in trap solutions. Both the abundance and identity of root-associated fungi influenced exudation. Exudation rates were greatest in root systems least colonized by ectomycorrhizal (ECM) fungi and most colonized by putative pathogenic and saprotrophic fungi. However, the ECM community composition was not a strong determinant of exudation rates. These results suggest that environmental conditions that influence the degree to which tree roots are colonized by pathogenic and saprotrophic vs. mutualistic fungi are likely to mediate fluxes of labile C in forest soils, with consequences for soil biogeochemistry and ecosystem processes. PMID:23013386

  10. Gravitropic response and circumnutation in pea (Pisum sativum) seedling roots.

    PubMed

    Kim, Hye-Jeong; Kobayashi, Akie; Fujii, Nobuharu; Miyazawa, Yutaka; Takahashi, Hideyuki

    2016-05-01

    Plant circumnutation is a helical movement of growing organs such as shoots and roots. Gravitropic response is hypothesized to act as an external oscillator in shoot circumnutation, although this is subject to debate. The relationship between circumnutational movement and gravitropic response in roots remains unknown. In this study, we analyzed circumnutation of agravitropic roots using the ageotropum pea (Pisum sativum) mutant, and compared it with that of wild-type (cv. Alaska) pea roots. We further examined the relationship of gravitropic response to circumnutation of Alaska seedling roots by removing the gravisensing tissue (the root cap) and by treating the roots with auxin transport inhibitors. Alaska roots displayed circumnutational movements with a period of approximately 150 min, whereas ageotropum roots did not exhibit distinct circumnutational movement. Removal of the root cap in Alaska roots reduced gravitropic response and circumnutational movements. Treatment of Alaska roots with auxin transport inhibitors, 2,3,5-triiodobenzoic acid (TIBA) and N-(1-naphthyl)phthalamic acid (NPA), dramatically reduced gravitropic response and circumnutational movements. These results suggest that a gravity-regulated auxin transport is involved in circumnutation of pea seedling roots. PMID:26565659

  11. [Allelopathy of different plants on wheat, cucumber and radish seedlings].

    PubMed

    Shen, Huimin; Guo, Hongru; Huang, Gaobao

    2005-04-01

    By means of bioassay in laboratory and field, this paper studied the allelopathy of 18 kinds of plants in Gansu Province on the seedlings of wheat, cucumber and radish. The results showed that the aqueous extract of the stems and leaves of Artemisia annua, Solanum nigrum and Datura stramonium had the strongest allelopathy on test receptor plants, and their synthetic inhibitory effect (SE) was 47.66%, 32.89% and 26.63%, respectively. The SE of Xanthium sibiricum, Portulaca oleraca, Cephalanoplos segetum, and Chenopodium album was 21.71%, 20.93%, 20.83% and 20.2%, respectively, while Vicia amoena (SE 3.5%), Setaria viridis (SE 2.2%), and Cymamchum chinense (SE 1.97%) had a weaker allelopathy. Chenopodium ambrosioides (SE - 1.03%), Polygonum caespitosum (SE - 1.63%) and Avena fatua (SE 5.33%) had no evident allelopathy, but Artemisia annua affected the seedling height and fresh weight of radish, cucumber, wheat and maize, with the SE being 54.07%, 38.46%, 33.35% and 20.88%, respectively. Artemisia annua had a 44.70% of SE on wheat growth, and thus, had a certain value to develop and use. PMID:16011179

  12. Lipoxygenase and Hydroperoxide Lyase in Germinating Watermelon Seedlings 1

    PubMed Central

    Vick, Brady A.; Zimmerman, Don C.

    1976-01-01

    Lipoxygenase (EC 1.13.1.13) was found in seedlings of Citrullus lanatus (Thunb.) Matsum. and Nakai (watermelon). The enzyme has pH optima of 4.4 and 5.5 and is inhibited by 0.2 mM nordihydroguaiaretic acid. It is present in two functional units with estimated molecular weights of 120,000 and 240,000, respectively. A new enzyme, tentatively termed hydroperoxide lyase, has been partially purified from watermelon seedlings. The enzyme, located principally in the region of the hypocotyl-root junction, catalyzes the conversion of 13-l-hydroperoxy-cis-9-trans-11-octadecadienoic acid to 12-oxo-trans-10-dodecenoic acid and hexanal. The hydroperoxide lyase enzyme from watermelon has a molecular weight in excess of 250,000, a pH optimum in the range of 6 to 6.5, and is inhibited by p-chloromercuribenzoic acid. Its presence has also been demonstrated in other cucurbits. The maximum activity of both enzymes occurs on the 6th day of germination. The identification of the products of the hydroperoxide lyase reaction suggests that lipoxygenase and hydroperoxide lyase may be involved in the conversion of certain polyunsaturated fatty acids to traumatic acid (trans-2-dodecenedioic acid). PMID:16659569

  13. Effects of Graphene on Germination and Seedling Morphology in Rice.

    PubMed

    Liu, Shangjie; Wei, Hongmin; Li, Zhiyang; Li, Shun; Yan, Han; He, Yong; Tian, Zhihong

    2015-04-01

    The effects of graphene on the germination and growth of rice seeds were studied. Seeds were treated with graphene solutions at different concentrations. Obvious delaying effects on the germination rate were observed with the increasing of graphene concentration. The growth of radicle and plumule was inhibited. And also, the morphology (root length, stem length, adventitious number, root fresh weight, fresh weight of over ground part and root cap ratio) of rice seedlings was certainly affected. After been treated by different concentrations of graphene for 16 d, promoting effects on adventitious root number, root fresh weight and fresh weight of over ground part were observed at concentration of 5 mg/L. Significant inhibitions on the stem length and fresh weight of over ground part were observed at concentration of 50 mg/L. In addition, all the indexes were inhibited at concentrations of 100 mg/L and 200 mg/L. It indicates that graphene certainly inhibit the morphogenesis of rice seedlings. But the mechanism by which graphene of 5 mg/L improves part of growth indexes still needs further study. PMID:26353483

  14. Linking carbon and water relations to drought-induced mortality in Pinus flexilis seedlings.

    PubMed

    Reinhardt, Keith; Germino, Matthew J; Kueppers, Lara M; Domec, Jean-Christophe; Mitton, Jeffry

    2015-07-01

    Survival of tree seedlings at high elevations has been shown to be limited by thermal constraints on carbon balance, but it is unknown if carbon relations also limit seedling survival at lower elevations, where water relations may be more important. We measured and modeled carbon fluxes and water relations in first-year Pinus flexilis seedlings in garden plots just beyond the warm edge of their natural range, and compared these with dry-mass gain and survival across two summers. We hypothesized that mortality in these seedlings would be associated with declines in water relations, more so than with carbon-balance limitations. Rather than gradual declines in survivorship across growing seasons, we observed sharp, large-scale mortality episodes that occurred once volumetric soil-moisture content dropped below 10%. By this point, seedling water potentials had decreased below -5 MPa, seedling hydraulic conductivity had decreased by 90% and seedling hydraulic resistance had increased by >900%. Additionally, non-structural carbohydrates accumulated in aboveground tissues at the end of both summers, suggesting impairments in phloem-transport from needles to roots. This resulted in low carbohydrate concentrations in roots, which likely impaired root growth and water uptake at the time of critically low soil moisture. While photosynthesis and respiration on a leaf area basis remained high until critical hydraulic thresholds were exceeded, modeled seedling gross primary productivity declined steadily throughout the summers. At the time of mortality, modeled productivity was insufficient to support seedling biomass-gain rates, metabolism and secondary costs. Thus the large-scale mortality events that we observed near the end of each summer were most directly linked with acute, episodic declines in plant hydraulic function that were linked with important changes in whole-seedling carbon relations. PMID:26116925

  15. Cryopreservation affects ROS-induced oxidative stress and antioxidant response in Arabidopsis seedlings.

    PubMed

    Chen, Guan-Qun; Ren, Li; Zhang, Jie; Reed, Barbara M; Zhang, Di; Shen, Xiao-Hui

    2015-02-01

    Plant recovery status after cryopreservation by vitrification had a negative relationship to the oxidative stress induced by reactive oxygen species (ROS). Arabidopsis thaliana seedlings germinated for 48 h or 72 h with different survival tolerances were examined at five steps of cryopreservation, to determine the role of ROS (O2(-), H2O2 and OH) and antioxidant systems (SOD, POD, CAT, AsA and GSH) in cryo-injury. In addition, the effects of the steps on membrane lipid peroxidation were studied using malondialdehyde (MDA) as an indicator. The results indicated that H2O2-induced oxidative stress at the steps of dehydration and rapid warming was the main cause of cryo-injury of 48-h seedlings (high survival rate) and 72-h seedlings (no survival). The H2O2 was mainly generated in cotyledons, shoot tips and roots of seedlings as indicated by Amplex Red staining. Low survival of 72-h seedlings was associated with severe membrane lipid peroxidation, which was caused by increased OH generation activity and decreased SOD activity. The antioxidant-related gene expression by qRT-PCR and physiological assays suggested that the antioxidant system of 48-h seedlings were activated by ROS, and they mounted a defense against oxidative stress. A high level of ROS led to the weakening of the antioxidant system of 72-h seedlings. Correlation analysis indicated that enhanced antioxidant enzymes activities contributed to the high survival rate of 48-h seedlings, which could reflect by cryopreservation of antioxidant mutant seedlings. This model system indicated that elevated CAT activity and AsA content were determinants of cryogenic stress tolerance, whose manipulation could improve the recovery of seedlings after cryopreservation. PMID:25489814

  16. 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

  17. Effects of Burial in Sand and Water Supply Regime on Seedling Emergence of Six Species

    PubMed Central

    ZHENG, YUANRUN; XIE, ZHIXIAO; YU, YI; JIANG, LIANHE; SHIMIZU, HIDEYUKI; RIMMINGTON, GLYN M.

    2005-01-01

    • Background and Aims Air seeding has long been regarded as a quick and successful measure for vegetation rehabilitation in China. However, seedling emergence of often-used species including Agriophyllum squarrosum, Artemisia sphaerocephala, Artemisia ordosica, Hedysarum fruticosum, Caragana korshinskii and Medicago sativa is low. Experiments were conducted under controlled conditions to study the effects of sowing depth and water supply on seedling emergence, in order to understand the requirements for increasing seedling emergence. • Methods Seeds were exposed to different environments of burial and water supply regimes in PVC pots (7 cm in diameter and 11 cm in height) under the same light intensity and alternating temperature regimes in a growth chamber. • Key Results Seedlings of three species (Agriophyllum squarrosum, Artemisia sphaerocephala, Artemisia ordosica) with relatively light seeds emerged well at a 0·5 cm sowing depth under a 7·5 and 10 mm water supply regime. However, few seedlings of these species emerged when the sowing depth was over 1 cm or when water supply was 5 mm. Seedlings of Caragana korshinskii, Hedysarum fruticosum and Medicago sativa emerged from sowing depths of 0·5–4 cm, 0·5–3 cm, and 0·5–4 cm, respectively, under both 7·5 and 10 mm water supply regimes. Under a 5 mm water supply regime, seedlings of these species also emerged at over 1 cm sowing depth. Seeds of all six species sown on the surface of sand did not germinate, and seedlings did not emerge when they were sown at depths greater than 6 cm. • Conclusions Based on these experiments, a 0·5 cm sowing depth resulted in the highest seedling emergence and it is concluded that this is the optimal sowing depth for seedling emergence of all six species. PMID:15820988

  18. Can NPK fertilizers enhance seedling growth and mycorrhizal status of Tuber melanosporum-inoculated Quercus ilex seedlings?

    PubMed

    Suz, Laura M; Martín, María P; Fischer, Christine R; Bonet, José A; Colinas, Carlos

    2010-06-01

    Although successful cultivation of the black truffle (Tuber melanosporum) has inspired the establishment of widespread truffle orchards in agricultural lands throughout the world, there are many unknowns involved in proper management of orchards during the 6-10 years prior to truffle production, and there are conflicting results reported for fertilizer treatments. Here, we systematically evaluate the combined effects of nitrogen, phosphorous, and potassium with different doses of each element, applied to either foliage or roots, on plant growth parameters and the mycorrhizal status of outplanted 3-year-old seedlings in five experimental Quercus ilex-T. melanosporum orchards. Fertilization did not significantly improve seedling aboveground growth, but the plants treated with the fertilizer 12-7-7 applied to the roots (HNr) displayed longer field-developed roots. Only the fertilizer with the highest dose of K (10-6-28) applied to the foliage (HKf) increased the probability of fine root tip colonization by T. melanosporum in field-developed roots. However, the plants treated with the same fertilizer applied to the soil (HKr) presented the highest probability for colonization by other competing mycorrhizal soil fungi. Potassium seems to have an important role in mycorrhizal development in these soils. Apart from T. melanosporum, we found 14 ectomycorrhizal morphotypes, from which seven were identified to species level, three to genus, two to family, and two remained unidentified by their morphological characteristics and DNA analyses. PMID:20033737

  19. 90sr uptake by 'pinus ponderosa' and 'pinus radiata' seedlings inoculated with ectomycorrhizal fungi

    SciTech Connect

    Entry, J.A.; Rygiewicz, P.T.; Emmingham, W.H.

    1994-01-01

    In the study, the authors inoculated P. ponderosa and P. radiata seedlings with one of five isolates of ectomycorrhizal fungi; inoculated and nonincoculated (control) seedlings were compared for their ability to remove Sr90 from an organic growth medium. Seedlings were grown for 3 months in a growth chamber in glass tubes containing 165 cu cm of sphagnum peat moss and perlite and, except in the controls, the fungal inoculum. After 3 months, 5978 Bq of Sr90 in 1 ml of sterile, distilled, deionized water was added. Seedlings were grown for an additional month and then harvested. P. ponderosa seedlings that were inoculated with ectomycorrhizal fungi accumulated 3.0-6.0% of the Sr90; bioconcentration ratios ranged from 98-162. Inoculated P. radiata seedlings accumulated 6.0-6.9% of the Sr90; bioconcentration ratios ranged from 88-133. Noninoculated P. ponderosa and P. radiata seedlings accumulated only 0.6 and 0.7% of the Sr90 and had bioconcentration ratios of 28 and 27, respectively.

  20. Physiological and transcriptomic characterization of submergence and reoxygenation responses in soybean seedlings.

    PubMed

    Tamang, Bishal G; Magliozzi, Joseph O; Maroof, M A Saghai; Fukao, Takeshi

    2014-10-01

    Complete inundation at the early seedling stage is a common environmental constraint for soybean production throughout the world. As floodwaters subside, submerged seedlings are subsequently exposed to reoxygenation stress in the natural progression of a flood event. Here, we characterized the fundamental acclimation responses to submergence and reoxygenation in soybean at the seedling establishment stage. Approximately 90% of seedlings succumbed during 3 d of inundation under constant darkness, whereas 10 d of submergence were lethal to over 90% of seedlings under 12 h light/12 h dark cycles, indicating the significance of underwater photosynthesis in seedling survival. Submergence rapidly decreased the abundance of carbohydrate reserves and ATP in aerial tissue of seedlings although chlorophyll breakdown was not observed. The carbohydrate and ATP contents were recovered upon de-submergence, but sudden exposure to oxygen also induced lipid peroxidation, confirming that reoxygenation induced oxidative stress. Whole transcriptome analysis recognized genome-scale reconfiguration of gene expression that regulates various signalling and metabolic pathways under submergence and reoxygenation. Comparative analysis of differentially regulated genes in shoots and roots of soybean and other plants defines conserved, organ-specific and species-specific adjustments which enhance adaptability to submergence and reoxygenation through different metabolic pathways. PMID:24433575

  1. Sharing rotting wood in the shade: ectomycorrhizal communities of co-occurring birch and hemlock seedlings.

    PubMed

    Poznanovic, Sarah K; Lilleskov, Erik A; Webster, Christopher R

    2015-02-01

    Coarse woody debris (CWD) is an important nursery environment for many tree species. Understanding the communities of ectomycorrhizal fungi (ECMF)and the effect of ECMF species on tree seedling condition in CWD will elucidate the potential for ECMF-mediated effects on seedling dynamics. In hemlock-dominated stands, we characterized ECMF communities associated with eastern hemlock (Tsuga canadensis (L.) Carr) and yellow birch (Betula alleghaniensis Britt) seedling pairs growing on CWD. Seedling foliage and CWD were analyzed chemically, and seedling growth, canopy cover, and canopy species determined. Thirteen fungal taxa, 12 associated with birch, and 6 with hemlock, were identified based on morphology and ITS sequencing. Five species were shared by co-occurring birch and hemlock, representing 75% of ectomycorrhizal root tips. Rarified ECMF taxon richness per seedling was higher on birch than hemlock. Nonmetric multidimensional scaling revealed significant correlations between ordination axes, the mutually exclusive ECMF Tomentella and Lactarius spp., foliar N and K, CWD pH, and exchangeable Ca and Mg. Seedlings colonized by Lactarius and T. sublilacina differed significantly in foliar K and N, and CWD differed in exchangeable Ca and Mg. CWD pH and nutrient concentrations were low but foliar macro-nutrient concentrations were not. We hypothesize that the dominant ECMF are adapted to low root carbohydrate availability typical in shaded environments but differ in their relative supply of different nutrients. PMID:25091153

  2. Seedling Diversity in Hydatellaceae: Implications for the Evolution of Angiosperm Cotyledons

    PubMed Central

    Sokoloff, Dmitry D.; Remizowa, Margarita V.; Macfarlane, Terry D.; Tuckett, Renee E.; Ramsay, Margaret M.; Beer, Anton S.; Yadav, Shrirang R.; Rudall, Paula J.

    2008-01-01

    Background and Aims Cotyledon number has long been a primary morphological feature distinguishing monocots from other angiosperms. Recent placement of Hydatellaceae near the early-divergent angiosperm order Nymphaeales, rather than in the monocot order Poales, has prompted reassessment of seedling morphology in this poorly known family. Methods Seedlings of six species representing all eco-geographical groups of Hydatellaceae are described using light and scanning electron microscopy. Key Results Two seedling types were discovered. Material examined of Trithuria submersa, T. bibracteata, T. austinensis and T. filamentosa possess a transparent bilobed sheathing structure that surrounds the main axis below the first foliage leaf. The seed coat is attached to the sheathing structure. Seedlings of Trithuria lanterna and T. konkanensis lack a sheathing structure, and the seed coat is attached to a short, narrow lateral outgrowth on the main axis of the seedling. Conclusions The sheathing structure that is present in seedlings of some Hydatellaceae could be homologized with the two united cotyledons of water lilies. It also resembles the single cotyledon of some monocots, and hence demonstrates a possible pathway of the origin of a monocot-like embryo, though no homology is implied. The sheathing structure is reduced in Trithuria lanterna and T. konkanensis, and the short, narrow outgrowth of its seedling could represent a single cotyledon. This synapomorphy suggests that the only Indian species of Hydatellaceae, T. konkanensis, is closer to the northern Australian T. lanterna than to the south-western Australian T. bibracteata. PMID:18032428

  3. Retention of cotyledons is crucial for resprouting of clipped oak seedlings

    PubMed Central

    Yi, Xianfeng; Liu, Changqu

    2014-01-01

    Although resprouting plays an important role in facilitating persistence of damaged seedlings, the functional attributes of cotyledons and taproots during resprouting of 1-year oak seedlings are not well explored. In this study, cotyledons were removed from Quercus mongolica seedlings to explore resprouting in response to simulated disturbance as a function of shoot clipping, and to examine the resprouting ability in relation to timing of clipping and cotyledon removal. Isotope labeling experiments were also performed to evaluate contribution of the cotyledons and taproots to resprouting. Regardless of timing of shoot clipping, seedlings successfully resprouted provided their cotyledons were not detached. Clipped seedlings were less likely to resprout when cotyledons were removed. Seedlings clipped at earlier development stage exhibited higher resprouting capacity than those clipped at later stage. Cotyledon removal, more than timing of clipping, decreased the dry masses of newly-resprouted shoots. However, no significant influences of cotyledon removal and timing of clipping were found on the dry masses of roots, suggesting the importance of cotyledons for resprouting. Roots became functional and accumulated more soil nitrogen after shoot clipping and cotyledon removal, representing a double security-based strategy for the clipped seedlings to resprout despite the importance of cotyledons. PMID:24888417

  4. Retention of cotyledons is crucial for resprouting of clipped oak seedlings.

    PubMed

    Yi, Xianfeng; Liu, Changqu

    2014-01-01

    Although resprouting plays an important role in facilitating persistence of damaged seedlings, the functional attributes of cotyledons and taproots during resprouting of 1-year oak seedlings are not well explored. In this study, cotyledons were removed from Quercus mongolica seedlings to explore resprouting in response to simulated disturbance as a function of shoot clipping, and to examine the resprouting ability in relation to timing of clipping and cotyledon removal. Isotope labeling experiments were also performed to evaluate contribution of the cotyledons and taproots to resprouting. Regardless of timing of shoot clipping, seedlings successfully resprouted provided their cotyledons were not detached. Clipped seedlings were less likely to resprout when cotyledons were removed. Seedlings clipped at earlier development stage exhibited higher resprouting capacity than those clipped at later stage. Cotyledon removal, more than timing of clipping, decreased the dry masses of newly-resprouted shoots. However, no significant influences of cotyledon removal and timing of clipping were found on the dry masses of roots, suggesting the importance of cotyledons for resprouting. Roots became functional and accumulated more soil nitrogen after shoot clipping and cotyledon removal, representing a double security-based strategy for the clipped seedlings to resprout despite the importance of cotyledons. PMID:24888417

  5. Establishment of Ulmus pumila seedlings on steppe slopes of the northern Mongolian mountain taiga

    NASA Astrophysics Data System (ADS)

    Dulamsuren, Choimaa; Hauck, Markus; Nyambayar, Suran; Osokhjargal, Dalaikhuu; Leuschner, Christoph

    2009-09-01

    The potential of Siberian elm ( Ulmus pumila) to regenerate from seeds was experimentally studied on south-facing slopes in the northern Mongolian mountain taiga. These slopes are covered with a vegetation mosaic of different steppe communities and small, savanna-like, U. pumila open woodlands. The hypothesis is tested that the xeric microclimate and high herbivore densities limit the success of seedling establishment in U. pumila and thereby prevent elm from complete encroachment of the grassland-dominated slopes. Seeds were sown and 2-yr-old seedlings were planted prior to the growing season. The water supply was manipulated by irrigation, as was the feeding pressure by caterpillars with an insecticide. Large herbivores were excluded by fencing. Seeds germinated throughout the summer, but the emerged seedlings did not survive for more than 2 or 3 weeks. Germination rates increased with increasing soil water content and decreasing soil temperatures. Many seeds were consumed by granivores. Most planted 2-yr-old seedlings survived the two growing seasons covered by the study. However, the seedlings suffered from feeding damage by insects (gypsy moth, grasshoppers) and small mammals, from nitrogen deficiency and, to a lesser degree, from drought. The results suggest that high susceptibility of newly emerged seedlings to environmental stresses is a serious bottle neck for U. pumila that prevents them from the formation of closed forests on northern Mongolia's steppe slopes, whereas the probability for seedling survival after this early stage is high.

  6. Herbivory and seedling performance in a fragmented temperate forest of Chile

    NASA Astrophysics Data System (ADS)

    Simonetti, Javier A.; Grez, Audrey A.; Celis-Diez, Juan L.; Bustamante, Ramiro O.

    2007-11-01

    Forest fragmentation alters plant-animal interactions, including herbivory. Relying manipulative experiments, we test if the reduction in insect herbivory associated with forest fragmentation translates into increased seedling growth and survival of three tree common species ( Aristotelia chilensis, Cryptocarya alba and Persea lingue) in forest fragments and continuous forests in coastal Maulino forest, central Chile. Furthermore, we test if after protecting seedlings from herbivorous insects, plant performance is increased regardless of forest fragmentation. Nursery grown seedlings were transplanted into four forest fragments and a continuous forest during 2002. Insects, important herbivores in this forest, were excluded from half the seedlings by repeated applications of insecticides. Compared to continuous forests, in forest fragments, herbivory was reduced in all three species, seedling growth was greater in A. chilensis and C. alba but not in P. lingue, and survivorship was unaffected by herbivory or fragmentation in all three species. Protecting seedlings from insects reduced herbivory in the continuous forest to similar levels attained in the forest fragments. No change in herbivory results from by protecting seedlings in forest fragments. These results confirm that insects are important herbivores in the Maulino forest and also support the hypothesis that fragmentation can have strong indirect effects on plant communities as mediated through trophic interactions.

  7. Ethanolamide Oxylipins of Linolenic Acid Can Negatively Regulate Arabidopsis Seedling Development[C][W

    PubMed Central

    Keereetaweep, Jantana; Blancaflor, Elison B.; Hornung, Ellen; Feussner, Ivo; Chapman, Kent D.

    2013-01-01

    N-Acylethanolamines (NAEs) are fatty-acid derivatives with potent biological activities in a wide range of eukaryotic organisms. Polyunsaturated NAEs are among the most abundant NAE types in seeds of Arabidopsis thaliana, and they can be metabolized by either fatty acid amide hydrolase (FAAH) or by lipoxygenase (LOX) to low levels during seedling establishment. Here, we identify and quantify endogenous oxylipin metabolites of N-linolenoylethanolamine (NAE 18:3) in Arabidopsis seedlings and show that their levels were higher in faah knockout seedlings. Quantification of oxylipin metabolites in lox mutants demonstrated altered partitioning of NAE 18:3 into 9- or 13-LOX pathways, and this was especially exaggerated when exogenous NAE was added to seedlings. When maintained at micromolar concentrations, NAE 18:3 specifically induced cotyledon bleaching of light-grown seedlings within a restricted stage of development. Comprehensive oxylipin profiling together with genetic and pharmacological interference with LOX activity suggested that both 9-hydroxy and 13-hydroxy linolenoylethanolamides, but not corresponding free fatty-acid metabolites, contributed to the reversible disruption of thylakoid membranes in chloroplasts of seedling cotyledons. We suggest that NAE oxylipins of linolenic acid represent a newly identified, endogenous set of bioactive compounds that may act in opposition to progression of normal seedling development and must be depleted for successful establishment. PMID:24151297

  8. Organic nitrogen uptake of Scots pine seedlings is independent of current carbohydrate supply.

    PubMed

    Gruffman, Linda; Palmroth, Sari; Näsholm, Torgny

    2013-06-01

    In boreal forests, seedling establishment is limited by various factors including soil nitrogen (N) availability. Seedlings may absorb N from soil in a variety of inorganic and organic forms; however, the energy and thus carbohydrate requirements for uptake and assimilation of N vary with N source. We studied the importance of current photoassimilates for the acquisition and allocation of different N sources by Scots pine (Pinus sylvestris (L.)) seedlings. Girdling was used as a tool to impair phloem transport of photoassimilates, and hence gradually deprive roots of carbohydrates. Seedlings were cultivated in a greenhouse on equimolar N concentrations of one of the N sources-arginine, ammonium or nitrate-and then girdled prior to a pulse-chase uptake experiment with isotopically labeled N sources. Girdling proved to be efficient in decreasing levels of soluble sugars and starch in the roots. Uptake rate of arginine N was highest, intermediate for ammonium N and lowest for nitrate N. Moreover, the uptake of arginine N was unaffected by girdling, while the uptake of the two inorganic N sources decreased to 45-56% of the ungirdled controls. In arginine-treated seedlings, 95-96% of the acquired arginine N resided in the roots, whereas a significant shift in the N distribution toward the shoot was evident in girdled seedlings treated with inorganic N. This spatial shift was especially pronounced in nitrate-treated seedlings suggesting that the reduction and following incorporation into roots was limited by the availability of current photoassimilates. These results suggest that there are energetic benefits for seedlings to utilize organic N sources, particularly under circumstances where carbohydrate supply is limited. Hence, these putative benefits might be of importance for the survival and growth of seedlings when carbohydrate reserves are depleted in early growing season, or in light-limited environments, such as those sustained by continuous cover forestry systems

  9. [Roles of phenylalanine ammonia-lyase in low temperature tolerance in cucumber seedlings].

    PubMed

    Dong, Chun-juan; Li, Liang; Cao, Ning; Shang, Qing-mao; Zhang, Zhi-gang

    2015-07-01

    To reveal the roles of phenylalanine ammonia-lyase (PAL) in low temperature tolerance in cucumber seedlings, a specific PAL inhibitor (AOPP) was sprayed to the seedlings, and then the stress tolerance was determined. The results suggested that both gene expression and enzymatic activity of PAL in cucumber leaves were induced under low temperature. The seedlings pretreated with AOPP showed lower PAL activity and less accumulation of phenolics and flavonoids. Low temperature caused damages in cucumber seedlings, and pretreatment of AOPP aggravated these damages. Compared to the control, the seedlings pretreated with AOPP showed significantly higher relative electrolyte leakage and MDA production, lower maximum photochemical efficiency of PSII (Fv/Fm) but higher photo-chemical quenching coefficient Y(NO), and reduced expression of low temperature-responsive genes (PR1-la, COR47, P5CS and HSP70). In cucumber seedlings, low temperature stress induced the accumulation of H2O2, increased the contents of ascobate (AsA) but decreased the contents of dehydroascobate (DHA), and thus reduced the value of AsA: DHA. In the AOPP-pretreated seedlings, the activities of antioxidant enzymes (CAT and APX) were significantly repressed, and excess H2O2 accumulated. The value of AsA: DHA was also lower than the control. Furthermore, co-application of H2O2 scavenger alleviated the low temperature-induced damages in the AOPP-pretreated seedlings, while coapplication of a CAT inhibitor made the seedlings more sensitive to low temperature stress. These results indicated that under low temperature stress, the enhanced activities of PAL could increase the biosynthesis of phenylpropanoid compounds and activate the cellular antioxidant enzymes, which could scavenge the excess ROS and maintain the cellular redox status, and thereby reduce the photo- and oxidative damages caused by low temperature stress. PMID:26710630

  10. Temperature, precipitation and biotic interactions as determinants of tree seedling recruitment across the tree line ecotone.

    PubMed

    Tingstad, Lise; Olsen, Siri Lie; Klanderud, Kari; Vandvik, Vigdis; Ohlson, Mikael

    2015-10-01

    Seedling recruitment is a critical life history stage for trees, and successful recruitment is tightly linked to both abiotic factors and biotic interactions. In order to better understand how tree species' distributions may change in response to anticipated climate change, more knowledge of the effects of complex climate and biotic interactions is needed. We conducted a seed-sowing experiment to investigate how temperature, precipitation and biotic interactions impact recruitment of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) seedlings in southern Norway. Seeds were sown into intact vegetation and experimentally created gaps. To study the combined effects of temperature and precipitation, the experiment was replicated across 12 sites, spanning a natural climate gradient from boreal to alpine and from sub-continental to oceanic. Seedling emergence and survival were assessed 12 and 16 months after sowing, respectively, and above-ground biomass and height were determined at the end of the experiment. Interestingly, very few seedlings were detected in the boreal sites, and the highest number of seedlings emerged and established in the alpine sites, indicating that low temperature did not limit seedling recruitment. Site precipitation had an overall positive effect on seedling recruitment, especially at intermediate precipitation levels. Seedling emergence, establishment and biomass were higher in gap plots compared to intact vegetation at all temperature levels. These results suggest that biotic interactions in the form of competition may be more important than temperature as a limiting factor for tree seedling recruitment in the sub- and low-alpine zone of southern Norway. PMID:26065402