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Seed Longevity (seed + longevity)
Selected AbstractsEcological correlates of seed survival after ingestion by Fallow DeerFUNCTIONAL ECOLOGY, Issue 2 2005A. MAARTEN MOUISSIE Summary 1The survival and retention of seeds was studied by feeding known quantities of seeds of 25 species to four captive Fallow Deer (Dama dama L.). To test for ecological correlates, plant species were selected to represent large variation in seed size, seed shape, seed longevity and habitat fertility. 2Seeds of 24 out of 25 fed plant species survived ingestion and defecation by Fallow Deer. Seed survival ranged between 0ˇ5 and 42% of germinable seeds fed. Time to recover 50% of all seeds defecated by Fallow Deer in faeces averaged 25 h, and ranged from 13 to 38 h. 3Seed survival was negatively related to seed mass (R = 0ˇ65) and variance of unit seed dimensions (R = ,0ˇ56), and positively related to seed longevity (R = 0ˇ40), but not related to habitat fertility. Log10 of (seed mass × variance of seed dimensions) was the best predictor of seed survival (R = ,0ˇ68). 4The ecological correlates of seed survival presented here can help us to estimate the ability of plant species to disperse seeds over long distances. [source] Litter effects on plant regeneration in arid lands: a complex balance between seed retention, seed longevity and soil,seed contactJOURNAL OF ECOLOGY, Issue 4 2005JOSÉ L. ROTUNDO Summary 1The recovery of rare, threatened plant populations can sometimes be achieved through modification of the disturbance regime. Accumulation of litter is likely to follow a reduction in grazing pressure and we therefore examine its effects on seedling recruitment of a threatened species in a temperate arid rangeland. 2We studied the effects of litter on seed longevity in the field and performed glasshouse and field experiments with natural and plastic litter to assess their physical and biological/chemical nature. Seeds were sown on the soil surface, buried or within the litter layer. Published data on spatial distribution of seeds were used to calculate the net effect of litter on seedling recruitment. 3Litter increased seed longevity. In the glasshouse, litter increased seedling emergence and growth for surface, but not for buried, seeds. Seeds within the litter layer (no seed-soil contact) showed reduced seedling emergence and growth. In the field, litter did not have a direct effect but emergence was promoted by burial. 4Integrating the effects of microsite quality and seed density showed that litter microsites recruited c. 50% of Bromus pictus seedlings, double that expected from its cover (25%). The positive effect of litter on seed density and on seed longevity outweighed the negative effect of litter acting as a mechanical barrier to burial. 5Inconsistent effects of litter on plant recruitment in arid environments may be due to responses being dependent on seed size and shape, and thus may represent indirect effects acting via the probability of burial. Alternatively, studies may report effects only on seed retention or emergence and growth rather than net effects on establishment. [source] The influence of environmental factors, the pollen : ovule ratio and seed bank persistence on molecular evolutionary rates in plantsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2006C.-A. WHITTLE Abstract One of the main goals of molecular evolutionary biology is to determine the factors that influence the evolutionary rate of selectively neutral DNA, but much remains unknown, especially for plants. Key factors that could alter the mutation rate include environmental tolerances (because they reflect a plants vulnerability to changes in habitat), the pollen : ovule ratio (as it is associated with the number of mitotic divisions) and seed longevity (because this influences the number of generations per unit time in plants). This is the first study to demonstrate that seed bank persistence and drought tolerance are positively associated with molecular evolutionary rates in plants and that pollen : ovule ratio, shade tolerance and salinity tolerance have no detectable relationship. The implications of the findings to our understanding of the impact of environmental agents, the number of cell divisions and cell aging on neutral DNA sequence evolution are discussed. [source] Enhancing seed quality and viability by suppressing phospholipase D in ArabidopsisTHE PLANT JOURNAL, Issue 6 2007Shivakumar P. Devaiah Summary Seed aging decreases the quality of seed and grain and results in agricultural and economic losses. Alterations that impair cellular structures and metabolism are implicated in seed deterioration, but the molecular and biochemical bases for seed aging are not well understood. Ablation of the gene for a membrane lipid-hydrolyzing phospholipase D (PLD,1) in Arabidopsis enhanced seed germination and oil stability after storage or exposure of seeds to adverse conditions. The PLD,1-deficient seeds exhibited a smaller loss of unsaturated fatty acids and lower accumulation of lipid peroxides than did wild-type seeds. However, PLD,1 -knockdown seeds were more tolerant of aging than were PLD,1 -knockout seeds. The results demonstrate the PLD,1 plays an important role in seed deterioration and aging in Arabidopsis. A high level of PLD,1 is detrimental to seed quality, and attenuation of PLD,1 expression has the potential to improve oil stability, seed quality and seed longevity. [source] Can soil seed banks contribute to the restoration of dune slacks under conservation management?APPLIED VEGETATION SCIENCE, Issue 2 2009Katharina Plassmann Abstract Questions: Does the soil seed bank resemble the former early successional stages of a dune slack system more than the established later successional vegetation? Does it have the potential to contribute to the conservation of a highly endangered habitat? Location: Dune slacks at Newborough Warren, UK. Methods: The composition of the soil seed bank in two depth layers was determined using the seedling emergence method between March 2004 and April 2005. Long-term monitoring data on the floristic composition of the established vegetation were obtained from the national conservation agency, and additional monitoring was undertaken in 2003. Floristic composition, seed weights, seed longevity of component species and Ellenberg indicator values were used to compare the seed bank and established vegetation. Results: The soil seed bank was diverse and contained typical dune slack species, species of early successional stages and species of conservation interest. A comparison between the composition of the seed bank and historical data on the composition of the established vegetation showed that the seed bank reflects earlier successional stages more closely than the current aboveground vegetation. This study increases the scarce information currently available on the seed bank ecology of several species, including two orchid species. Conclusions: The soil seed bank can be expected to contribute to vegetation change after disturbance. Stimulation of germination from the seed bank through management may contribute to the conservation of both characteristic and threatened species typical of dune slacks. [source] The contribution of rewetting to vegetation restoration of degraded peat meadowsAPPLIED VEGETATION SCIENCE, Issue 3 2007J. van Dijk van der Meijden (1990) Abstract Question: What is the contribution of a rise in groundwater level to vegetation restoration of degraded peat meadows compared to abandonment only? Location: Abandoned peat meadows in the central part of The Netherlands. Methods: Comparison of species composition and species abundance of vegetation and seed banks of reference and rewetted peat meadows, using plant trait and seed bank analysis. Results: Vegetation of rewetted meadows shared on average only 27% of their species with the reference meadow, while this was 50% on average for species in the seed bank. Rewetted meadows had a lower total number of species and a lower number of wet grassland and fen species present in the vegetation, but had higher species richness per m2, although evenness was not affected. Rewetting increased the dominance of species of fertile and near neutral habitats, but did not result in an increase of species of wet or waterlogged habitats. Re-wetted meadows were dominated by species relying mainly on vegetative reproduction and species with a low average seed longevity compared to the reference meadow. Conclusion: Rewetting was not effective as a restoration measure to increase plant species diversity or the number of wet grassland and fen species in the vegetation. If no additional restoration management is applied, the seed bank will be depleted of seeds of species of wet grassland or fen habitats, further reducing the chances of successful vegetation restoration. [source] | ||||||||||