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Seedling
About: Seedling is a research topic. Over the lifetime, 28687 publications have been published within this topic receiving 478292 citations.
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TL;DR: Analyses of the California flora involving nearly 2,500 taxa are presented which show that there are correlations between the weights of individual seeds and environmental conditions in which their producers normally grow, with a general positive correlation between seed weights and rates of shoot and root growth.
Abstract: Analyses of the California flora involving nearly 2,500 taxa are presented which show that there are correlations between the weights of individual seeds and environmental conditions in which their producers normally grow. These differences in seed weight appear to be adaptive and result from compromises between increased nutrition of the seedling which would result from larger food reserves in heavier seeds and increased dispersibility and increased reproductive output which are provided when smaller seeds are produced in larger numbers. Literature and experiments show a general positive correlation between seed weights and rates of shoot and root growth, at least within species. Herbs (annual and perennial), shrubs and trees are necessarily treated separately in the calculations in this paper (for seed weights increase progressively in a series from annual herb to tree when to California flora or any particular community type within it are considered). Raw seed weights are reduced to a series of classes (on a logarithmic basis) before means for floras or community types are calculated. Generalizations arrived at from considerations of "native" species in "natural" plant communities are confirmed by their applicability to "introduced" species now forming various kinds of "weed" communities in California. Finally, species lists from actual stand analyses, including both "native" and "introduced" species, are utilized to provide the data for more precise analyses. For herbaceous plants, seed weights are higher, on the average, for taxa whose seedlings are exposed to the risk of drought soon after establishment (giving faster root—development). Such a relationship can be demonstrated for species of a single genus or, on a combination basis, for community types as a whole and can be put on a quantitative basis by subjectively ordinating community types (in relation to the likelihood of drought stress hitting the seedlings) and making rank correlations with mean seed weight for each community type. The relation holds even for desert communities (where large—seeded perennials produce large root—systems but small—seeded ephemerals complete at least their seedling development in temporarily mesic conditions). In coastal communities, the importance of wind—dispersal of the seeds of species whose seedlings become established in rock crevices outweighs any droughtiness of the habitat in favoring smaller seeds than typify the community types generally. Correlations of herb seed—weight with likelihood of seedlings becoming established in shade or in conditions of severe competition are less marked for California than Salisbury found them to be in England. For shrubs, shading and competitive stress appear to be more influential factors in promoting increased mean seed weight but for trees moisture availability again appears to be most important. Another kind of correlation is established; between mean seed weight and altitude at which the plants occur. With decreasing length of the growing season as Californian mountains are ascended the mean seed weight (whether measured on a subspecies, species or community type basis) also decreases. This appears to represent the selection of a strategy in which a reduction in the availability of photosynthate is reflected in smaller seeds rather than in reduced output as found in Ranunculus by Johnson and Cook. Although taxa introduced to California have fitted with the rules holding for native plants, they tend to have slightly heavier seeds than native species growing in climatically similar habitat types. This difference may be particularly related to human influence in making such habitats somewhat more xeric. Improved methods of analysis are suggested and further correlations which might be sought are discussed.
744 citations
TL;DR: It was concluded that inhibition of germination at the same water potential of NaCl and PEG resulted from osmotic effect rather than salt toxicity, and hydropriming increased germination and seedling growth under salt and drought stresses.
743 citations
TL;DR: In this article, the effects of nanoscale zinc oxide particles on plant growth and development were examined in the case of peanut seeds, and the effect of nanoscopic ZnO (25 nm mean particle size) at 1000 ppm concentration was found to promote seed germination and seedling vigor.
Abstract: An investigation was initiated to examine the effects of nanoscale zinc oxide particles on plant growth and development. In view of the widespread cultivation of peanut in India and in other parts of the globe and in view of the potential influence of zinc on its growth, this plant was chosen as the model system. Peanut seeds were separately treated with different concentrations of nanoscale zinc oxide (ZnO) and chelated bulk zinc sulfate (ZnSO4) suspensions (a common zinc supplement), respectively and the effect this treatment had on seed germination, seedling vigor, plant growth, flowering, chlorophyll content, pod yield and root growth were studied. Treatment of nanoscale ZnO (25 nm mean particle size) at 1000 ppm concentration promoted both seed germination and seedling vigor and in turn showed early establishment in soil manifested by early flowering and higher leaf chlorophyll content. These particles proved effective in increasing stem and root growth. Pod yield per plant was 34% higher compared to...
741 citations
TL;DR: It remains unclear whether competition among seedlings is a decisive influence on species composition in most of the world's vegetation types, as there is startlingly wide variation in seed mass among species growing interspersed with each other.
Abstract: Seed mass is correlated with a number of other plant traits, including dispersal mode, growth form and specific leaf area. Specific leaf area is the main determinant of potential relative growth rate and an indicator of the site quality to which a species is adapted. The relationships with dispersal mode and growth form have consistent form in five datasets from three continents, and each account for about 20-30% of variation in log seed mass. Thus, there is also very substantial variation within growth form and dispersal categories. Much, but not all, of the 20-30% is associated with shifted family composition between growth forms or dispersal modes. Experiments have shown that seedlings of larger-seeded species are better able to survive hazards including deep shade, drought, physical damage and the presence of competing vegetation. If there is a common mechanism under these different hazards, it seemingly must be a `reserve effect', whereby during deployment and early growth larger-seeded species hold a bigger percentage of seed reserves uncommitted to seedling structure and available to support respiration or repair damage. A reserve effect has not yet been demonstrated directly. It remains possible that different mechanisms operate under different hazards. Under a reserve effect, advantages of larger seed size should be temporary, and temporary advantage has indeed been observed with regard to seedling survival under dense shade. Although larger seed mass confers benefits on seedlings, larger seeds must necessarily be produced in smaller numbers per unit of resource allocated. Seed mass is presumed to have evolved as a compromise between these counterposed pressures. Yet there has proved to be surprisingly little difference in average seed mass between very different vegetation regions, at least in temperate climates. Rather, there is startlingly wide variation in seed mass among species growing interspersed with each other. Recent applications of game theory may be capable of accounting for this wide variation between coexisting species, but at present these models are driven by competition among seedling species (as opposed to between seedlings and adults). It remains unclear whether competition among seedlings is a decisive influence on species composition in most of the world's vegetation types.
670 citations
TL;DR: Upregulation of the anti-oxidant system appears to play a role in salt tolerance of rice, with tolerant genotypes also maintaining relatively higher photosynthetic function; during both the vegetative and reproductive stages.
627 citations