Seed-coat thickness data clarify seed size–seed-bank persistence trade-offs inAbutilon theophrasti(Malvaceae)

2014 ◽  
Vol 24 (2) ◽  
pp. 119-131 ◽  
Author(s):  
Brian J. Schutte ◽  
Adam S. Davis ◽  
Stephen A. Peinado ◽  
Jamshid Ashigh

AbstractTheoretical models predict that seed size and seed-bank persistence evolve interdependently, such that strong selection for one trait corresponds with weak selection for the other. This framework has been supported and rejected by empirical data, and thus, conclusive evidence is lacking. We expanded the seed size–persistence framework to include seed-coat thickness, a defence trait previously correlated with seed survival in soil. To do this, we usedAbutilon theophrastiaccessions with varied evolutionary histories and we quantified associations among seed traits including morphology, size, coat thickness, dormancy (percentage of viable seeds that fail to germinate under optimum conditions) and seed-bank persistence (percentage of viable seeds remaining after 1 year of burial). Statistical models were developed to test the hypothesis that combined measurements of seed-coat thickness and seed size better explain variability in seed-bank persistence than seed-size data alone. Results indicated that measurements of seed size (length, width, mass) were negatively correlated with coat:width ratio (coat thickness relative to seed width) and coat:mass ratio (coat thickness relative to seed mass). Accessions characterized by smaller seeds with proportionally thicker seed coats were more dormant and more persistent in soil than accessions characterized by larger seeds with proportionally thinner seed coats. Seed-coat thickness data improved the explanatory power of logistic regression models for seed-size effects on both seed-bank persistence and dormancy. These results indicate that supplementing seed-size data with seed-defence data may clarify previously reported contradictory results regarding trade-offs between seed size and seed-bank persistence.

2001 ◽  
Vol 52 (10) ◽  
pp. 985 ◽  
Author(s):  
Z. H. Miao ◽  
J. A. Fortune ◽  
J. Gallagher

Selection and breeding for yield and adaptation to environmental conditions often changes a number of characteristics of crops, and may influence the value of seed for animals. A series of experiments was conducted to evaluate the effect of breeding and growing conditions on the structure and degradability of lupin seed coats. Breeding has had significant influences on both seed size and seed coat structure of lupins. For instance, cultivars of Lupinus angustifolius released in 1987 and 1988 tended to have smaller seeds with a thicker seed coat than those released in 1971 (P < 0.05). Selection for soft seeds has resulted in a reduction of seed coat thickness in L. angustifolius. Hardseeded and roughseeded lines of L. cosentinii had thicker coats (P < 0.05) than softseeded and smoothseeded, respectively. The main contributor to the thick seed coat of hardseeded lines was a layer of cells known as the hourglass layer, which is located between the outer palisade and inner parenchyma. Anatomical analysis revealed that the soft seed coat tended to have short and round cells, whereas the hard seed tended to have long cells in the palisade layer. Smooth seeds had round cells in the subpalisade, but rough seeds had long cells in this layer. Although the seed coats of lupins contained about 80% crude fibre, with L. cosentinii and L. pilosus having more fibre than L. angustifolius, the fibre in lupin seed coats was highly digestible by sheep.


Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 757
Author(s):  
Foffová Hana ◽  
Ćavar Zeljković Sanja ◽  
Honěk Alois ◽  
Martinková Zdenka ◽  
Tarkowski Petr ◽  
...  

Ground beetles are important invertebrate seed predators in temperate agro-ecosystems. However, there is a lack of information regarding which seed properties are important to carabids when they select seeds for consumption. Therefore, seed properties, such as size, shape, morphological defence, and chemical composition, were measured, and in addition to seed taxonomy and ecology, these data were used to explain carabid preferences. Carabid preferences were assessed using a multi-choice experiment with 28 species of weed seeds presented to 37 species of Carabidae. Multiple regression on distance matrices (MRM) was used to determine the importance of particular sets of seed properties for carabids. The analysis was conducted for the full set of carabids (37 species) as well as for subsets of species belonging to the tribes of Harpalini or Zabrini. For the complete set of species, seed dimensions, seed mass, taxonomy, plant strategy, and seed coat properties significantly explained carabid preferences (proportion of explained variance, R2 = 0.465). The model for Harpalini fit the data comparably well (R2 = 0.477), and seed dimensions, seed mass and seed coat properties were significant. In comparison to that for Harpalini, the model for Zabrini had much lower explanatory power (R2 = 0.248), and the properties that significantly affected the preferences were seed dimensions, seed mass, taxonomy, plant strategy, and seed coat properties. This result suggests that the seed traits that carabids respond to may be specific to taxonomic and likely relate to the degree of specialisation for seeds. This study contributes to understanding the mechanisms that determine the preferences of carabid beetles for seeds.


2009 ◽  
Vol 14 (2) ◽  
pp. 153-160
Author(s):  
Mangadas Lumban Gaol ◽  
J.E.D. Fox

The aim of this study was to investigate to what extent are germination of A. fauntleroyi affected by seed size. Does pre-treatment improve germination? Under what temperature regime does most seed germinate? Three seed size classes (small, medium and large) were chosen. Seeds were pre-treatments either at ambient, 50°C, 75°C or 100°C and incubated at 15°C or 30°C. Then, number of seed that germinate and speed of germination were measure. Five seeds representing each of small, medium and large seed sizes were also selected and the seed coat thickness measured. Seed size, pre-treatment temperature and incubation temperature all affected the number of seed that germinated. Pre-treatment temperature affected germination more than incubation temperature. Incubation temperature affected germination more than seed size. The interaction of seed size and pre-treatment temperature was stronger than that between seed size and incubation temperature. Small seeds produce less germination than medium or large seeds, however small seed germinated sooner. Seed coat thickness varied among seed sizes. Thinner seed coats occur in smaller than larger seeds.


1998 ◽  
Vol 8 (4) ◽  
pp. 513-519 ◽  
Author(s):  
P. E. Hulme

AbstractThis study examines whether post-dispersal seed predators could be an important selective force in determining the seed bank strategies of grassland plants. It tests the hypothesis that species with persistent seed banks should sustain proportionally less predation of buried seeds than species which have transient seed banks and that this should be true irrespective of seed size. Results are drawn from a field experiment examining the relative susceptibility of surface versus buried seeds for 19 herbaceous taxa exhibiting different degrees of seed bank persistence. The data were consistent with the hypothesis that seed predators (rodents) influence the seed bank characteristics of seeds. Rodents removed proportionally more large seeds than small seeds and removed a smaller proportion of seeds with persistent rather than transient seed banks, independently of seed size. On average, burial reduced seed removal by almost 50%. The decrease in rates of seed removal following burial was marked for seeds with persistent seed banks but negligible for seeds with transient seed banks. Herbaceous plants with relatively large seeds (seed mass > 1 mg) that form persistent seed banks were either completely avoided or only consumed in small quantities by rodents. In contrast, large-seeded species with transient seed banks suffer high rates of seed predation. Models of life-history evolution predict trade-offs between seed dormancy and seed mass since dormancy and seed size are correlated traits that both reduce risk in variable environments and thus will show patterns of negative covariation. This paper presents an alternative explanation for this trade-off based on experimental evidence of a negative relationship between seed bank persistence and predation risk.


2012 ◽  
Vol 22 (3) ◽  
pp. 161-167 ◽  
Author(s):  
R.F. Parsons

AbstractA group of flowering plant species is known to germinate in less than 24 h from imbibition, but this phenomenon is often overlooked in the current literature. Here, I review this topic by searching the literature published since 1967 and listing the 28 most detailed cases found. Of these, 20 are species of Amaranthaceae (all formerly treated as Chenopodiaceae); 15 of these are from the subfamily Salsoloideae, which is characterized by the possession of spiral embryos. The non-chenopods listed are small numbers of species from the families Acanthaceae, Cruciferae, Gramineae (one species) and Salicaceae (Populus and Salix). Seeds of the Salsoloideae contain fully differentiated embryos. On imbibition, the embryo cells elongate and the spiral embryo uncoils and ruptures the thin seed coat. This can occur in as little as 10 min. Nearly all of the families showing very fast germination have small to very small seeds and little or no endosperm. Most species have soft, thin seed coats that imbibe water readily. All are from high-stress habitats, either arid or saline or from active floodplains, where they can rapidly exploit temporarily favourable conditions for germination. They exhibit one of two contrasting germination behaviours, either having seeds which all germinate within a very short time of wetting or having seed persistence whereby small amounts of rain cause germination of small fractions of seed from a long-living soil seed bank. Serious confusion in the literature in the use of the term ‘opportunistic’ is pointed out and clarified.


2010 ◽  
Vol 20 (4) ◽  
pp. 223-236 ◽  
Author(s):  
Suzanne M. Kosina ◽  
Steven R. Schnebly ◽  
Ralph L. Obendorf

AbstractRaffinose, stachyose and phytin are undesirable compounds for soybean food and animal feed products. In seeds, raffinose and stachyose are believed to contribute to desiccation and cold stress tolerance. Thus, removal of these compounds from soybean by genetic mutation has resulted in a more commercially desirable composition, but potentially less physiologically viable seeds. In an effort to develop a method to improve viability and seed storability in soybean, stem–leaf–pod explants of three low raffinose, low stachyose lines, two of which were also low in phytin, and a check line were fed solutions containing d-chiro-inositol, myo-inositol or d-pinitol, free cyclitols which unload through the seed coat to the developing embryo where they accumulate as fagopyritols, galactinol and galactopinitols, respectively, during seed maturation. Increased galactopinitol and fagopyritol accumulation may substitute for the roles of raffinose and stachyose in low raffinose, stachyose and phytin seeds. Explants of all lines unloaded d-chiro-inositol, myo-inositol and d-pinitol. Fed d-chiro-inositol accumulated in leaf tissues demonstrating uptake into explants. Fed d-chiro-inositol and myo-inositol accumulated in pod wall and seed coat tissues of one or more lines. The results indicate that d-chiro-inositol was unloaded from the seed coat to the embryo in increased amounts after feeding. The potential use of increased maternal d-chiro-inositol for synthesis of fagopyritols in embryos to improve seed performance in low-stachyose and low-phytin soybean seeds is supported. The seed coat cup unloading of fed free cyclitols may provide a model system to test effective unloading of upregulated maternally synthesized cyclitols.


2005 ◽  
Vol 272 (1570) ◽  
pp. 1357-1364 ◽  
Author(s):  
Lindsay A Turnbull ◽  
Liz Manley ◽  
Mark Rees

Pioneer species are fast-growing, short-lived gap exploiters. They are prime candidates for neutral dynamics because they contain ecologically similar species whose low adult density is likely to cause widespread recruitment limitation, which slows competitive dynamics. However, many pioneer guilds appear to be differentiated according to seed size. In this paper, we compare predictions from a neutral model of community structure with three niche-based models in which trade-offs involving seed size form the basis of niche differentiation. We test these predictions using sowing experiments with a guild of seven pioneer species from chalk grassland. We find strong evidence for niche structure based on seed size: specifically large-seeded species produce fewer seeds but have a greater chance of establishing on a per-seed basis. Their advantage in establishment arises because there are more microsites suitable for their germination and early establishment and not directly through competition with other seedlings. In fact, seedling densities of all species were equally suppressed by the addition of competitors' seeds. By the adult stage, despite using very high sowing densities, there were no detectable effects of interspecific competition on any species. The lack of interspecific effects indicates that niche differentiation, rather than neutrality, prevails.


Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3833
Author(s):  
Fatma M. Elessawy ◽  
Albert Vandenberg ◽  
Anas El-Aneed ◽  
Randy W. Purves

Pulse crop seed coats are a sustainable source of antioxidant polyphenols, but are typically treated as low-value products, partly because some polyphenols reduce iron bioavailability in humans. This study correlates antioxidant/iron chelation capabilities of diverse seed coat types from five major pulse crops (common bean, lentil, pea, chickpea and faba bean) with polyphenol composition using mass spectrometry. Untargeted metabolomics was used to identify key differences and a hierarchical analysis revealed that common beans had the most diverse polyphenol profiles among these pulse crops. The highest antioxidant capacities were found in seed coats of black bean and all tannin lentils, followed by maple pea, however, tannin lentils showed much lower iron chelation among these seed coats. Thus, tannin lentils are more desirable sources as natural antioxidants in food applications, whereas black bean and maple pea are more suitable sources for industrial applications. Regardless of pulse crop, proanthocyanidins were primary contributors to antioxidant capacity, and to a lesser extent, anthocyanins and flavan-3-ols, whereas glycosylated flavonols contributed minimally. Higher iron chelation was primarily attributed to proanthocyanidin composition, and also myricetin 3-O-glucoside in black bean. Seed coats having proanthocyanidins that are primarily prodelphinidins show higher iron chelation compared with those containing procyanidins and/or propelargonidins.


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