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Seed Size (seed + size)
Selected AbstractsStudy of selected quality and agronomic characteristics and their interrelationship in Kabuli-type chickpea genotypes (Cicer arietinum L.)INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2006Amal Badshah Khattak Summary Impact of genotype on quality, agronomic characteristics and their interrelationship in Kabuli-type chickpea was investigated to provide significant feedback to breeder for selection/evolution of the most suitable varieties. Seven genotypes were studied for seventeen physical, chemical and agronomic characteristics. The effect of Kabuli-type chickpea genotype on the physicochemical parameters, cooking time and agronomic characteristics were significant. Maximum seed size and volume were recorded for CC98/99 (0.32 g and 0.26 mL seed,1, respectively), density and swelling index for the genotype FLIP97-179C (having minimum seed size and volume), while the rest of the genotypes were statistically the same. Weight, volume after hydration, hydration capacity and swelling capacity followed the same pattern. Maximum moisture, protein and mineral concentration were noted in CC98/99. Seed protein concentration for the remaining genotypes was statistically non-significant from one another. Longer period was taken by CM 2000 for flowering and maturity (130 and 181 days, respectively). Minimum time to flowering and maturity was taken by CC98/99. Genotype CC 98/99 outyielded all other genotypes (2107 kg ha,1). Seed size and seed volume were strongly and positively correlated with protein content, weight after hydration, volume after hydration, hydration and swelling capacities (r = 0.83,1.0). Strong correlation was also noted among different agronomic characters. [source] COMPARISON OF INSTRUMENTAL METHODS FOR MEASURING SEED HARDNESS OF FOOD-GRADE SOYBEANJOURNAL OF TEXTURE STUDIES, Issue 1 2008BO ZHANG ABSTRACT Breeding specialty soybeans for the soyfood market requires proper methodology in evaluation of seed quality attributes. In this study, efficient methods that could be potentially used for testing soybean seed hardness were developed by examining different instruments and seed parameters. Five food-grade soybean genotypes with different seed sizes were used to determine seed water-absorption capacity and hardness. Water absorption capacity was expressed by swell ratios for seed weight, seed dimension, and volume of water changes before and after soaking. Seed hardness test was conducted by a one-bite method using a food texture analyzer equipped with five different probes. The results showed that hardness testing by a 75 mm cylinder with 10 steamed seeds, single blade with five steamed seeds, and shear cell with 30 g steamed seeds produced dependable and consistent results with low coefficient of variance. However, shear cell may not be practical for early plant selection in a breeding program due to a relatively large sample requirement. Seed size can be used as indirect selection indicators for seed hardness. PRACTICAL APPLICATIONS Seed hardness is an important factor in determining soybean suitability for natto production. This study used two texture analyzers equipped with five different probes to test hardness of five soybean genotypes with different seed size. The methodologies for testing the seed texture of soybean have been established, which can help regulate the seed hardness testing for commercial production and provide consistent hardness references for natto breeding programs and the seed industry. [source] Seed size and response to rainfall patterns in annual grasslands: 16 years of permanent plot dataJOURNAL OF VEGETATION SCIENCE, Issue 1 2009B. Peco Abstract Question: Are seed size and plant size linked to species responses to inter-annual variations in rainfall and rainfall distribution during the growing season in annual grasslands? Location: A 16-year data set on species abundance in permanent plots 15 km north of Madrid in a Quercus ilex subsp. ballota dehesa. Methods: At species level, a GLM was used to analyse the effects of various rainfall indices (total autumn rainfall, early autumn rainfall and spring drought) on species abundance residuals with respect to time and topography. We also assessed the importance of seed size and plant size in the species responses at community level using species as data points. Seed mass and maximum stem length were used as surrogates for seed size and plant size, respectively. Results: Seed mass and plant size may explain some of the fluctuations in the floristic composition of annual species associated with autumn rainfall patterns. Species that are more abundant in dry autumns have greater seed mass than those species that are more abundant in wet autumns. Early autumn rainfall seems to favour larger plants. Conclusions: Our empirical results support the hypothesis that autumn rainfall patterns affect the relative establishment capacity of small and large seedlings in annual species. [source] The effect of twig architecture and seed number on seed size variation in subtropical woody speciesNEW PHYTOLOGIST, Issue 4 2009Hong Chen Summary ,,This study aims to determine the effect of twig (current year shoot) size on seed size variation and to test whether a seed size vs number tradeoff occurs for the twigs of subtropical broad-leaved species. ,,Fruit-bearing twigs were sampled for 55 woody species (including 33 evergreen and 22 deciduous dicot species) from a southwest Chinese forest. Twig size, fruit size and number, and seed size and number were measured for each species. The relationships among these functional traits were determined both across species and across correlated phyletic divergences. ,,Total fruit mass and total seed mass were positively correlated with twig size. Seed size was positively associated with fruit size, which was, in turn, positively correlated with twig diameter, but negatively correlated with the ratio of twig length to diameter. The effect of twig size on seed size variation was not significant, possibly as a result of the large variation in seed number per fruit. Cross-species and across-phyletic divergence analyses revealed that seed size was negatively and isometrically correlated with seed number per twig mass in both the evergreen and deciduous species groupings, demonstrating the existence of tradeoff between seed size and number. ,,A seed size vs number tradeoff is detectable in the twigs of woody species. Comparatively little of the variance in seed size was attributable to twig size variation. [source] Contribution of direct and maternal genetic effects to life-history evolutionNEW PHYTOLOGIST, Issue 3 2009Laura F. Galloway Summary ,,Maternal effects are ubiquitous in nature. In plants, most work has focused on the effects of maternal environments on offspring trait expression. Less is known about the prevalence of genetic maternal effects and how they influence adaptive evolution. Here, we used multivariate genetic models to estimate the contributions of maternal and direct genetic (co)variance, the cross-generation direct-maternal covariance, and M, the matrix of maternal effect coefficients, for life-history traits in Campanulastrum americanum, a monocarpic herb. ,,Following a three-generation breeding design, we grew paternal half-sib families with full-sib relatives of each parent and measured juvenile and adult traits. ,,Seed size was influenced exclusively by maternal environmental effects, whereas maternal genetic effects influenced traits throughout the life cycle, including strong direct and maternal additive genetic correlations within and between generations for phenological and size traits. Examination of M suggested that both juvenile and adult traits in maternal plants influenced the expression of offspring traits. ,,This study reveals substantial potential for genetic maternal effects to contribute to adaptive evolution including cross-generation direct-maternal correlations that may slow selection response, maternal effects on phenology that reinforce genetic correlations, and within- and between-generation genetic correlations that may influence life-history polymorphism. [source] Ignorant seed predators and factors affecting the seed survival of a tropical palmOIKOS, Issue 1 2001Steven W. Brewer In addition to acting as seed predators, some terrestrial mammals bury seeds via scatter hoarding. This study system used two permanent plots in examining the interaction between small rodents and the seeds of the palm Astrocaryum mexicanum. We tested how experimental burial, and fruiting status of the parent, distance to the parent, seed size, and microsite characteristics affect the survival of these seeds. Up to 34% of the buried seeds that were exposed only to ignorant rodent foragers (individuals not responsible for burial) survived. In comparison, less than 1% of seeds buried by scatter hoarding rodents survived in previous studies, a percentage that is comparable to the low survival of unburied seeds in this study (<2%). Although unburied seeds had very low survival, increasing distance and/or seed density positively affected survival of unburied seeds. Distance to parent had no effect on buried seed survival. Buried seed survival was most strongly and significantly determined by the fruiting status of the trees under which they occurred. Seeds experienced significantly greater predation if buried under "parent" trees that fruited during the experiment. Buried seed survival was also negatively affected by germination, as germination may signal the presence of a seed to foraging rodents. There was some indication of a positive effect of tree density on seed survival between the two plots, whereas differences in rodent abundance appear to have no effect on seed survival. Seed size and microsite characteristics had no significant effect on buried seed survival, likely due to the greater proportional effects of other factors and the longevity of A. mexicanum seeds. The results of this study were used to generate a hypothetical causal network showing how comparatively low recovery of buried seeds by ignorant foragers , combined with processes determining the removal of scatter hoarding foragers from their scattered seed caches , may affect seedling recruitment in A. mexicanum. [source] Variations in size structure, growth and reproduction in Japanese plantain (Plantago asiatica L.) between exposed and shaded populationsPLANT SPECIES BIOLOGY, Issue 1 2001Tsuyoshi Kobayashi Abstract Plantago asiatica is a perennial herb that is distributed over a wide range of east Eurasia. The population structure, growth and reproduction in exposed (E-) and shaded (S-) populations of P. asiatica were examined in the Kanto District of eastern Japan. In both populations, the plant size structure showed a bimodal distribution during spring to early summer, in which the two modes corresponded to smaller seedlings and larger overwintered plants, respectively. In autumn, this distribution became unimodal due to seedling growth. However, this change occurred later in the S-population because of suppressed growth in the seedlings. In the S-population, flowering also began later in the growing season and the threshold plant size for flowering was larger than that of the E-population. Biomass allocation to the rhizomes was greater in autumn in the reproductive plants of the S-population. Growth and biomass allocation in plants grown from seeds collected from each population were compared under phytotron conditions. Near a saturated photon flux density, E-population plants had a higher relative growth rate than S-population plants. Therefore, E-population plants should allocate resources to reproductive organs sooner. Shaded population plants were not vigorous in their growth and reproduction. Seed size (dry weight per grain) was significantly greater in the S-population than in the E-population, both in the field and under phytotron conditions. These results suggest that ecotypic differentiation in life-history strategies, which is mainly due to light availability, occurs among local P. asiatica populations. The effects of severe trampling on early reproduction in the E-population are also discussed. [source] Diplochory in two Jatropha (Euphorbiaceae) species of the Monte Desert of ArgentinaAUSTRAL ECOLOGY, Issue 2 2010ADRIANA A. RICKERT Abstract The potential explosive seed dispersal under controlled conditions and the dispersal by ants in natural populations are compared between two diplochoric species: Jatropha hieronymi Kuntze and J. excisa Griseb. The seeds of J. hieronymi are more than eightfold heavier than J. excisa seeds, and were explosively dispersed considerably further distances, reaching a maximum of almost 18 m. The differences in explosive dispersal distances between the two species seem to depend on both carpel wall thickness of the fruit and aerodynamic shape of the seed. Seed removal by ants was positively correlated with the presence of the elaiosome and was higher for J. excisa (83.6%) than for J. hieronymi (31.6%). Seed size was the major factor affecting the removal by ants, as only large bodied ants were able to transport the large seeds of J. hieronymi. The larger size and the higher oleic acid content of the elaiosomes of J. hieronymi seeds had no influence on the observed removal rates by ants. In contrast, ants transported the J. hieronymi seeds further distances than J. excisa seeds. Jatropha hieronymi distances achieved by both dispersal modes are in the range of the furthest distances described for a diplochorous species. Finally, the possible advantages of this dispersal mode in arid zones are discussed. [source] Seed Dispersal of a High Quality Fruit by Specialized Frugivores: High Quality Dispersal?,BIOTROPICA, Issue 2 2000Daniel G. Wenny ABSTRACT Dispersal quality, as estimated by the cumulative effects of dispersal, germination, seed predation, and seedling survival, was examined for Beilschmiedia pendula (Lauraceae) in Monteverde, Costa Rica. I determined the pattern of dispersal by finding seeds deposited by birds, protected the seeds from seed predators with cages to assess germination and seedling survival, and examined seed predation rates with marked seeds. Seed predation, germination, and seedling survival were compared between seeds naturally dispersed by birds and seeds placed at randomly located sites. Approximately 70 percent of seeds dispersed by birds (N= 244) were deposited <10 m from crown edges of fruiting B. pendula trees, although some seeds were dispersed at least 70 m away. Larger seeds were more likely to be dispersed under or close to the parent trees, and larger seeds produced larger seedlings. Seed size was not correlated directly with seedling survival, but larger seedlings at three months were most likely to survive one year. Seed predation by mammals and insects and seedling mortality due to fungal pathogens were concentrated beneath the crowns of parent trees. Seedlings and saplings were more abundant beneath fruiting B. pendula trees, but individuals farther away were taller on average. Thus, dispersal is beneficial for B. pendula, but such benefits appear most pronounced at a small spatial scale; seeds dispersed >30 m from the crown edges actually had a lower probability of survival than those dispersed 10,20 m. Only 10 percent of B. pendula. seeds received high-quality dispersal in terms of landing in the zone with the highest per seed probability of seedling survival 10,20 m from parental crowns. RESUMEN La calidad de dispersión, estimado del efecto acurnulativo de dispersión, germinación, predación de semillas, y sobrevivencia de plantulas fue examinada por Beikcbmiedia pendula (Lauracea) en Monteverde, Costa Rica. Determinté el partén de disperstón, encontrando semillas defecadas o regurgitadas por aves, protegi semillas de predatores con jaulas para determinar germinación y sobrevivencia de plantulas, y examiné la proporción de predación de semillas con semillas marcadas. Predación de semillas, germinación y sobrevivencia de plantulas fueron comparadas con semillas dispersadas naturalmente por aves y con semillas localizadas en lugares al azar. Aproximadamente 70 porcento de las semillas dispersadas por aves (N = 244) fueron depositadas cerca de 10 mdel horde de la corona de árboles en fruto de B. pendula, aunque algunas semillas fueron dispersadas hasta 70 m mas lejos. Semillas grandes tuvieron la tendencia de ser dispersadas debajo o cerca del Brbol parental, y semillas grandes produjeron plantulas grandes. El tamańo de la semilla no estaba correlacionada directamente con sobrevivencia de plantulas, pero plantulas grandes a 3 mesa tuvieron la tendencia de sobrevivir. Predación de semillas por los roedores y insectos, y mortalitad de plantulas por hongos patogtnicos fueron lo mas comun debajo de la corona de los árboles parentales. Plantulas y arbolillos fueron mós abundantes debajo de drboles en fruto de B. pendula, pero individuos distantes fueron en promedio más altos. Dispersión es favorable para B. pendula, pero estos beneficios aparentan ser más ptonunciados a una escala espacial menot; semillas dispersadas más de 30 m del horde de la corona en realidad tienen una probabilidad menor de sobrevivencia que las que son dispersadas entre 10,20 m. Solamente 10 porcento de las seniillas de B. pendula recibieron despersión de calidad alta en terminos de aterrizar en una zona con la más alta probabilidad de sobrevivencia de plantulas entre 10,20 m de la corona parental. [source] Effects of search experience in a resource-heterogeneous environment on the oviposition decisions of the seed beetle, Callosobruchus maculatus (F.)ECOLOGICAL ENTOMOLOGY, Issue 4 2006ROU-LING YANG Abstract 1.,This study investigates how female seed beetles, Callosobruchus maculatus, distribute their eggs on various-sized seeds when the size of seed was varied during the egg-laying period. 2.,Beetles were allowed to lay eggs on one of three arrays of 64 adzuki beans (Vigna angularis). Each array contained four size classes of seed, ranging from small (5.0,5.5 mm diameter) to large (6.5,7.0 mm), but differed in how they were distributed within the environment. In the most heterogeneous condition (the 64-patch design), the four sizes were interspersed, while in the least heterogeneous condition (the four-patch design) they were grouped into four separate blocks. Thus, a beetle exploring the 64-patch design would frequently encounter all four seed sizes, whereas a beetle exploring the four-patch design would only rarely encounter a change in bean size. 3.,Beetles experiencing greater seed size heterogeneity were more likely to lay eggs on larger seeds, whereas those in the blocked condition were more likely to oviposit on small seeds. Beetle responses to seed size heterogeneity suggest that the degree of preference for large seeds depends on a female's recent experience. 4.,Female beetles exhibited size discrimination throughout their egg-laying process; however, there was a trade-off between seed size and egg discrimination (i.e. avoiding those seeds already containing developing eggs) in response to the change in fitness gained from either laying on larger seeds or lower egg-load seeds during the egg-laying process. 5.,Our model provides the first evidence that evolving seed size discrimination ability is adaptive for the seed beetle with egg-discrimination ability. [source] Does a latitudinal gradient in seedling survival favour larger seeds in the tropics?ECOLOGY LETTERS, Issue 10 2004Angela T. Moles Abstract The mean size of seeds produced by plants at the equator is two to three orders of magnitude higher than the mean size of seeds produced by plants at 60°. We compiled data from the literature to assess the possibility that this latitudinal gradient in seed size allows species to cope with more difficult seedling establishment conditions in tropical environments. We found no relationship between latitude and seedling survival through 1 week (P = 0.27, n = 112 species). There was also no evidence that a larger seed mass is required to gain a given level of seedling survival in tropical environments (P = 0.37, n = 112 species), and no relationship between latitude and the duration of the juvenile period (P = 0.57, n = 132 species). Thus, our results are not compatible with the idea that seedling establishment is more difficult in the tropics. [source] Predicting competition coefficients for plant mixtures: reciprocity, transitivity and correlations with life-history traitsECOLOGY LETTERS, Issue 4 2001R.P. Freckleton There are few empirical or theoretical predictions of how per capita or per individual competition coefficients for pairs of plant species should relate to each other. In contrast, there are a considerable number of general hypotheses that predict competitive ability as a function of a range of ecological traits, together with a suite of increasingly sophisticated models for competitive interactions between plant species. We re-analyse a data set on competition between all pairwise combinations of seven species and show that competition coefficients relate strongly to differences between the maximum sizes, root allocation, emergence time and seed size of species. Regressions suggest that the best predictor of competition coefficients is the difference in the maximum size of species and that correlations of the other traits with the competition coefficients occur through effects on the maximum size. We also explore the patterns of association between coefficients across the competition matrix. We find significant evidence for coefficient reciprocity (inverse relationships between the interspecific coefficients for species pairs) and transitivity (numerically predictable hierarchies of competition between species) across competition matrices. These results therefore suggest simple null models for plant community structure when there is competition for resources. [source] DISASSORTATIVE MATING, SEXUAL SPECIALIZATION, AND THE EVOLUTION OF GENDER DIMORPHISM IN HETERODICHOGAMOUS ACER OPALUSEVOLUTION, Issue 7 2008Gabriela Gleiser In sexually polymorphic species, the morphs are maintained by frequency-dependent selection through disassortative mating. In heterodichogamous populations in which disassortative mating occurs between the protandrous and protogynous morphs, a decrease in female fitness in one morph is hypothesized to drive sexual specialization in the other morph, resulting in dimorphic populations. We test these ideas in a population of the heterodichogamous species, Acer opalus. We assessed both prospective gender of individuals in terms of their allocations and actual parentage using microsatellites; we found that most matings in A. opalus occur disassortatively. We demonstrate that the protogynous morph is maintained by frequency-dependent selection, but that maintenance of males versus protandrous individuals depends on their relative siring success, which changes yearly. Seeds produced later in the reproductive season were smaller than those produced earlier; this should compromise reproduction through ovules in protandrous individuals, rendering them male biased in gender. Time-dependent gender and paternity analyses indicate that the sexual morphs are specialized in their earlier sexual functions, mediated by the seasonal decrease in seed size. Our results confirm that mating patterns are context-dependent and change seasonally, suggesting that sexual specialization can be driven by seasonal effects on fitness gained through one of the two sexual functions. [source] CO2 and nitrogen, but not population density, alter the size and C/N ratio of Phytolacca americana seedsFUNCTIONAL ECOLOGY, Issue 3 2005J.-S. HE Summary 1Plants can provision seeds by optimizing seed size, number and nutrient content to maximize parental fitness. According to the McGinley,Charnov hypothesis, seed size should be determined by the ratio of carbon to nitrogen (C/N) available to the plant, with larger seed size correlating with larger C/N ratios and smaller absolute N content. 2This hypothesis was tested by establishing monocultures of Phytolacca americana L. (Phytolaccaceae) at three population densities under ambient and elevated CO2 environments, with two availabilities of soil N. 3Elevated CO2 reduced both seed size and N concentration while increasing the C/N ratio; high soil N availability produced the opposite result for N concentration and C/N ratio. Higher planting densities reduced plant biomass, but did not alter seed size. 4In accordance with the McGinley,Charnov hypothesis, larger seeds had both larger C/N ratios and smaller N content. However, the increase in C/N ratio caused by elevated CO2 corresponded with smaller seeds overall: elevated CO2 reduced seed size, although the seed size,C/N relationship remained positive. 5These results suggest an alternative mechanism to explain variation in seed size, and suggest that future climate conditions may alter seed quality and plant reproductive behaviour. [source] Ecological 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 0·5 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 = 0·65) and variance of unit seed dimensions (R = ,0·56), and positively related to seed longevity (R = 0·40), but not related to habitat fertility. Log10 of (seed mass × variance of seed dimensions) was the best predictor of seed survival (R = ,0·68). 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] Do shade-tolerant tropical tree seedlings depend longer on seed reserves?FUNCTIONAL ECOLOGY, Issue 4 2002Functional growth analysis of three Bignoniaceae species Summary 1.,A functional growth analysis was used to determine the duration of strict dependency on seed reserves for energy and nitrogen in three woody Bignoniaceae species (Tabebuia rosea DC., Challichlamys latifolia K. Schum. and Pithecoctenium crucigerum A. Gentry) which differed in cotyledon function (photosynthetic, semi-photosynthetic and storage) and shade tolerance (probability of seedling establishment and survival in the understorey). 2.,Seedlings were raised from seeds in sand culture under combinations of three nitrogen levels (daily supply of nutrient solution containing 100, 10 and 0% of 2·6 mm N) and two irradiances (27 and 1% full sun). Time course of biomass, non-cotyledonous biomass and leaf area for 40 days post-germination were compared to identify when the external availability of nitrogen or light began to affect seedling growth. 3.,Seedlings of all species became dependent on external energy supply earlier than they did on nitrogen supply. In all species seed nitrogen was sufficient to support positive seedling growth for 40 days in shade, but not in sun. 4.,Tabebuia rosea with photosynthetic cotyledons responded to light availability earlier than more shade-tolerant species with storage cotyledons. Challichlamys latifolia, the most shade-tolerant species, had the highest nitrogen concentration in seeds and was the last to respond to external nitrogen availability. Thus seedlings of the most shade-tolerant species depended on seed reserves for the longest period for both energy and nitrogen. 5.,Relative growth rate after seedlings initiated autotrophic growth was in a trade-off relationship with seedling survivorship in the understorey across the three species. Tabebuia rosea, the least shade-tolerant species, had the highest positive net carbon balance in sun and shade. 6.,Functional morphology of cotyledons and concentration of seed nitrogen deserve as much attention as seed size as correlates of contrasting seedling regeneration strategies. [source] Effects of elevated temperature and carbon dioxide on seed-set and yield of kidney bean (Phaseolus vulgaris L.)GLOBAL CHANGE BIOLOGY, Issue 8 2002P. V. Vara Prasad Abstract It is important to quantify and understand the consequences of elevated temperature and carbon dioxide (CO2) on reproductive processes and yield to develop suitable agronomic or genetic management for future climates. The objectives of this research work were (a) to quantify the effects of elevated temperature and CO2 on photosynthesis, pollen production, pollen viability, seed-set, seed number, seeds per pod, seed size, seed yield and dry matter production of kidney bean and (b) to determine if deleterious effects of high temperature on reproductive processes and yield could be compensated by enhanced photosynthesis at elevated CO2 levels. Red kidney bean cv. Montcalm was grown in controlled environments at day/night temperatures ranging from 28/18 to 40/30 °C under ambient (350 µmol mol,1) or elevated (700 µmol mol,1) CO2 levels. There were strong negative relations between temperature over a range of 28/18,40/30 °C and seed-set (slope, ,,6.5% °C,1) and seed number per pod (, 0.34 °C,1) under both ambient and elevated CO2 levels. Exposure to temperature >,28/18 °C also reduced photosynthesis (, 0.3 and ,,0.9 µmol m,2 s,1 °C,1), seed number (, 2.3 and ,,3.3 °C,1) and seed yield (, 1.1 and ,,1.5 g plant,1 °C,1), at both the CO2 levels (ambient and elevated, respectively). Reduced seed-set and seed number at high temperatures was primarily owing to decreased pollen production and pollen viability. Elevated CO2 did not affect seed size but temperature >,31/21 °C linearly reduced seed size by 0.07 g °C,1. Elevated CO2 increased photosynthesis and seed yield by approximately 50 and 24%, respectively. There was no beneficial interaction of CO2 and temperature, and CO2 enrichment did not offset the negative effects of high temperatures on reproductive processes and yield. In conclusion, even with beneficial effects of CO2 enrichment, yield losses owing to high temperature (> 34/24 °C) are likely to occur, particularly if high temperatures coincide with sensitive stages of reproductive development. [source] Impact of seeding rate on annual ryegrass performanceGRASS & FORAGE SCIENCE, Issue 1 2004B. C. Venuto Abstract Annual ryegrass (Lolium multiflorum Lam.) is a primary forage resource for livestock producers throughout the south-eastern USA during the winter-growing season. It is important for livestock producers to begin grazing annual ryegrass as early as possible and any management practices maximizing early season production could be beneficial. To assess the impact of seeding rate on subsequent yield, yield distribution, quality, seedling density, and end-of-season plant and tiller density, a 2-year study was initiated at four locations in Louisiana. Three annual ryegrass cultivars, varying in seed size, were established at four seeding rates based on pure live seed (PLS) rates of 400, 800, 1200 and 1600 PLS m,2. There was no advantage in total yield from increasing seeding rates beyond 800 PLS m,2. However, first-harvest yields increased from 360 to 930 kg dry matter (DM) ha,1 as seeding rate increased from 400 to 1600 PLS m,2. Crude protein and neutral-detergent fibre concentrations, and in vitro DM digestibility, were not affected by seeding rate. Seedling density and end-of-season plant numbers increased as seeding rate increased. However, stems per plant decreased as seeding rate increased, indicating compensatory tillering for the reduced plant numbers observed at the lower seeding rates. These results indicate first-harvest yield can be increased by planting at higher seeding rates but total yields are not increased. [source] Diversity examination based on physical, technological and chemical traits in a locally grown landrace of faba bean (Vicia faba L. var. major)INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 12 2009Giovanni Avola Summary Fifteen accessions of a locally adapted Sicilian population (,Larga di Leonforte') of faba bean were evaluated for their physical and technological properties and chemical composition. Results showed a high seed weight (1000 seed weight around 2500 × g) along with a great seed size with wide variability among accessions. When all data were combined, the seeds initial water uptake was 0.21 g min,1. Differences between accessions were found in hydration capacity (ranging between 133% and 160%) and retainable firmness after 40 min of cooking (ranging between 18.8 and 13.6 N cm,2). In addition, the average contents of 46.0, 25.2 and 2.6 g 100 g,1 dry weight basis were ascertained for starch, protein and tannin, respectively, with considerable variation among accessions. The result's interpretation, carried out through a methodological approach based on multivariate analysis, seem to support the view that parameters such as seed dimension, starch, protein and tannin content, can be effectively adopted as elements of comparison among landraces in grain legumes. [source] Study of selected quality and agronomic characteristics and their interrelationship in Kabuli-type chickpea genotypes (Cicer arietinum L.)INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2006Amal Badshah Khattak Summary Impact of genotype on quality, agronomic characteristics and their interrelationship in Kabuli-type chickpea was investigated to provide significant feedback to breeder for selection/evolution of the most suitable varieties. Seven genotypes were studied for seventeen physical, chemical and agronomic characteristics. The effect of Kabuli-type chickpea genotype on the physicochemical parameters, cooking time and agronomic characteristics were significant. Maximum seed size and volume were recorded for CC98/99 (0.32 g and 0.26 mL seed,1, respectively), density and swelling index for the genotype FLIP97-179C (having minimum seed size and volume), while the rest of the genotypes were statistically the same. Weight, volume after hydration, hydration capacity and swelling capacity followed the same pattern. Maximum moisture, protein and mineral concentration were noted in CC98/99. Seed protein concentration for the remaining genotypes was statistically non-significant from one another. Longer period was taken by CM 2000 for flowering and maturity (130 and 181 days, respectively). Minimum time to flowering and maturity was taken by CC98/99. Genotype CC 98/99 outyielded all other genotypes (2107 kg ha,1). Seed size and seed volume were strongly and positively correlated with protein content, weight after hydration, volume after hydration, hydration and swelling capacities (r = 0.83,1.0). Strong correlation was also noted among different agronomic characters. [source] Pre-dispersal acorn predation in mixed oak forests: interspecific differences are driven by the interplay among seed phenology, seed size and predator sizeJOURNAL OF ECOLOGY, Issue 6 2009Josep M. Espelta Summary 1.,Pre-dispersal seed predation (PSP) often occurs in multi-host,predator systems (e.g. several plant species exposed to a common array of granivorous insects). However, whether the interaction among seed phenology, seed size and predator size accounts for interspecific differences in PSP remains elusive. 2.,We studied PSP in a mixed-oak forest with two oaks (the larger-seeded Quercus humilis and the smaller-seeded Q. ilex), both depredated by two acorn weevils (the smaller Curculio glandium and the larger C. elephas). We intensively monitored acorn production and infestation phenology and we identified the weevil species depredating acorns by means of DNA taxonomy. 3.,The minimum acorn size required for infestation was lower for C. glandium than for C. elephas, in accordance with their different body sizes. This resulted in an earlier infestation phenology in C. glandium and the ability of this species to infest both smaller and larger acorns. Above a minimum acorn size threshold, no selection for larger acorns by weevils was observed. 4.,Initial acorn crop size was similar in the two oaks. Nonetheless, the earlier acorn phenology and the production of larger acorns in Q. humilis favoured the earlier infestation by C. glandium and the predation by both small and large weevils. Smaller acorns of Q. ilex almost excluded infestation by the larger C. elephas. 5.,Although larger acorns of Q. humilis could better survive infestation (preserve the embryo), higher PSP in this species finally resulted in a lower mature acorn crop size than in Q. ilex. 6.,Synthesis. In a multi-host,predator system, smaller-seeded species may benefit from a reduced PSP because they exclude larger granivorous insects, but also by means of a ,free-rider effect', if larger-seeded heterospecifics earlier reach a critical size to be depredated. These results also highlight the benefits of a small body size in granivorous insects to depredate seeds earlier and to forage on a wider range of seed sizes. Whether the advantage of ,being small' in this antagonistic plant,animal interaction is offset by other processes, or whether it results in a pressure towards seed and insect size reduction, deserves further attention. [source] Interspecific variation in primary seed dispersal in a tropical forestJOURNAL OF ECOLOGY, Issue 4 2008Helene C. Muller-Landau Summary 1We investigated the relationships of seed size, dispersal mode and other species characteristics to interspecific variation in mean primary seed dispersal distances, mean annual seed production per unit basal area, and clumping of seed deposition among 41 tropical tree species on Barro Colorado Island, Panama. 2A hierarchical Bayesian model incorporating interannual variation in seed production was used to estimate seed dispersal, seed production, and clumping of seed rain for each species from 19 years of data for 188 seed traps on a 50-ha plot in which all adult trees were censused every 5 years. 3Seed dispersal was modelled as a two-dimensional Student's T distribution with the degrees of freedom parameter fixed at 3, interannual variation in seed production per basal area was modelled as a lognormal, and the clumping of seed rain around its expected value was modelled as a negative binomial distribution. 4There was wide variation in seed dispersal distances among species sharing the same mode of seed dispersal. Seed dispersal mode did not explain significant variation in seed dispersal distances, but did explain significant variation in clumping: animal-dispersed species showed higher clumping of seed deposition. 5Among nine wind-dispersed species, the combination of diaspore terminal velocity, tree height and wind speed in the season of peak dispersal explained 40% of variation in dispersal distances. Among 31 animal-dispersed species, 20% of interspecific variation in dispersal distances was explained by seed mass (a negative effect) and tree height (a positive effect). 6Among all species, seed mass, tree height and dispersal syndrome explained 28% of the variation in mean dispersal distance and seed mass alone explained 45% of the variation in estimated seed production per basal area. 7Synthesis. There is wide variation in patterns of primary seed rain among tropical tree species. Substantial proportions of interspecific variation in seed production, seed dispersal distances, and clumping of seed deposition are explained by relatively easily measured plant traits, especially dispersal mode, seed mass, and tree height. This provides hope for trait-based generalization and modelling of seed dispersal in tropical forests. [source] The evolution of rewards: seed dispersal, seed size and elaiosome sizeJOURNAL OF ECOLOGY, Issue 3 2006WILL EDWARDS Summary 1We examine the relationship between the reward offered to ants to disperse seeds (elaiosome size) and seed size, and the possible mechanisms that may generate this relationship in Australian plant species. 2We used seed and elaiosome sizes from our own data set containing 87 Acacia species, supplemented with 22 species from a previously published data set, and 98 ,Other species' from 51 genera in 25 families, also from published data. 3The relationship between ln(elaiosome size) and ln(seed size) was determined using standard major axis (SMA) regression for both data sets. For the Other data set we also determined the relationship among species independent of the differences between genera, among genera independent of the differences between families, among genera and among families. We used SMA to test for differences in slopes between groups. 4We found a significant common slope amongst all subsets of the larger data set. The estimated common slope and the 95% confidence interval for the relationship between ln(elaiosome size) and ln(seed size) across all data sets fell above one (1.24, 95%CI = 1.17,1.32), suggesting positive allometry. Slopes were also significantly positive and strikingly similar between the Acacia species data set and the Other species data sets. Similar positive allometry was shown in the ,other' species data set among genera and families, and among species independent of genus means (,species effects'). 5Significant and consistent relationships between taxonomic levels, independent of relationships at other levels, along with significant relationships at the species level, and similarity of slopes, suggest independent convergence towards an underlying functional relationship that has persisted over long evolutionary periods. Our results therefore suggest that ants have been agents of selection on seed traits. 6Such a functional relationship might result from a trade-off in ant foraging behaviour between the benefit of the reward (elaiosome) and the cost of the dispersal (determined by seed size). Slopes > 1 would then suggest that ants need more than proportionally larger rewards to remove larger seeds. [source] Seed limitation in a Panamanian forestJOURNAL OF ECOLOGY, Issue 5 2005JENS-CHRISTIAN SVENNING Summary 1The role of seed limitation in tropical forests remains uncertain owing to the scarcity of experimental evidence. We performed seed addition experiments to assess seed limitation for 32 shade-tolerant tropical forest species and monitored the natural seed rain of 25 of these species for 17 years. 2One, two or five seeds were sown into 0.0079-m2 plots for large- (n = 5 species), medium- (n = 5) and small-seeded species (n = 22), respectively. The experiment was replicated at 69 sites, placed in groups of three at 23 locations. Seedling establishment was evaluated after 1 and 2 years in paired seed addition and control plots. Natural seedling emergence and understorey plant density were also measured. 3Median natural seed rain was 0.31 seeds m,2 year,1 per focal species. 4Seed addition enhanced seedling establishment in 31 and 26 of the 32 species after 1 and 2 years, respectively. Mean number of focal species' seedlings after 2 years was 0.002 seedlings in control plots and 0.12, 0.37 and 0.60 seedlings in seed addition plots for large-, medium- and small-seeded species, respectively. 5A 25 seeds added treatment increased seedling establishment by , 2.0-fold over the five seeds added treatment after 2 years. 6Community-wide recruitment and understorey plant density were strongly seed-limited. The natural density of understorey plants averaged 12 plants m,2 and was significantly less than for seedlings of the single focal species in plots with , 2 seeds added 2 years earlier. 7The number of established seedlings per seed added was independent of seed size. 8Treatment (adding zero or five seeds), species identity and location all affected seedling establishment for the 11 small-seeded species represented at all sites, with treatment and its interactions accounting for 86% of the explained variation. 9Our results suggest that seed limitation plays a dominant role in seedling recruitment and understorey plant community assembly in tropical forests. Although strong seed limitation may set the stage for species-neutral community assembly, the species differences in seedling establishment rate and its spatial variation demonstrate an important role for species-specific processes. [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] Seedling survival and seed size: a synthesis of the literatureJOURNAL OF ECOLOGY, Issue 3 2004ANGELA T. MOLES Summary 1Large-seeded species have long been known to have higher survivorship during establishment than small-seeded species. Here, we assessed the size of this advantage by compiling published data on survival through seedling emergence, seedling establishment and sapling establishment. 2We found no relationship between seed mass and survival through the transition from viable seed in or on the soil to newly emerged seedlings (P = 0.47, n = 33 species). 3Synthesis of data from experimental studies on the advantages of large-seeded species establishing under particular hazards (such as shade, drought or herbivory) confirmed that seedlings of large-seeded species perform better than those of small-seeded species in most situations. However, the magnitude of this advantage was not sufficient to counterbalance the greater number of seeds produced by small-seeded species m,2 of canopy outline year,1. 4Synthesis of data from field studies of populations under natural conditions also showed that large-seeded species have higher survival through early seedling establishment than small-seeded species (P = 0.006, n = 112 species). However, the magnitude of this advantage would only be sufficient to counterbalance the greater number of seeds produced by small-seeded species m,2 of canopy outline year,1 if mortality continued at the same rate for some time. 5The time required for a species with 10-fold larger seeds to recoup the advantage gained by a smaller-seeded species during seed production ranged from 8.8 weeks for the smallest seeded species in the data set, up to an implausible 4.2 years for the largest-seeded species. Thus, while large-seeded species do have a survival advantage over small-seeded species during seedling establishment, the available evidence suggests that advantages must also accrue during other stages in the life cycle. One possibility is that the greater seed production of small-seeded species (m,2 of canopy outline year,1) is partly offset by larger canopies and longer reproductive life spans in large-seeded species. [source] Seed mass and the competition/colonization trade-off: competitive interactions and spatial patterns in a guild of annual plantsJOURNAL OF ECOLOGY, Issue 1 2004Lindsay A. Turnbull Summary 1We used neighbourhood modelling to estimate individual-level competition coefficients for seven annuals growing in limestone grassland over 2 years. We calculated the relative strength of intra- and interspecific competition and related this to differences in seed size and plant size between targets and neighbours. 2Significant differences in the impact of neighbours on each target species were observed in half the models fitted, allowing us to reject a null hypothesis of competitive equivalence. 3In one year we found that as the seed size or plant size of neighbours increased relative to targets, so did their competitive effect. Although this is consistent with the competition/colonization trade-off model the competitive interactions were not sufficiently asymmetric to allow coexistence. In a second year we found only weak interspecific competition and no relationship with plant or seed size. 4We found no overall relationship between competition coefficients and the degree of segregation, contradicting the spatial segregation hypothesis for coexistence. However, segregation was linked to differences in plant traits: when targets were smaller than neighbours the degree of segregation increased with relative neighbour size. 5Most species were positively associated with each other due to a shared preference for otherwise unvegetated patches. The degree of association was negatively correlated with differences in plant and seed size, particularly when interspecific competition was weak. This might reflect (i) decreasing overlap in microhabitat use with increasing trait divergence or (ii) density-dependent mortality. 6Seed size is a key trait within this group of species, determining both competitive and colonizing ability. The presence of such a competition/colonization trade-off undoubtedly stabilizes community dynamics although other mechanisms may also be at work. [source] Ecological aspects of seed desiccation sensitivityJOURNAL OF ECOLOGY, Issue 2 2003John C. Tweddle Summary 1The ability of seeds to survive desiccation is an important functional trait and is an integral part of plant regeneration ecology. Despite this, the topic has received relatively little attention from ecologists. In this study, we examine the relationships between seed desiccation tolerance and two important aspects of plant regeneration ecology: habitat and dormancy. This is done by comparative analysis of a data set of 886 tree and shrub species from 93 families. 2The proportion of species displaying desiccation sensitive seeds declines as the habitat becomes drier, and possibly also cooler, although the latter observation requires cautious interpretation. Desiccation sensitivity is most common in moist, relatively aseasonal vegetation zones, but is infrequent in, though not absent from arid and highly seasonal habitats. 3The highest frequency of desiccation sensitivity occurs in non-pioneer evergreen rain forest trees, although 48% of the species examined have desiccation tolerant seeds. In contrast, all pioneer taxa within the data set have drying tolerant seeds. 4Desiccation sensitivity is more frequent in seeds that are non-dormant on shedding (c. 31%), than dormant (c. 9%). Highest frequencies of drying tolerance occur in seeds with physical or combinational dormancy, at 99% and 100%, respectively. 5Although there is an association between non-dormancy and desiccation sensitivity in both tropical and temperate zones, the relationship does not appear to be causal. 6Working from the hypothesis that seed desiccation sensitivity represents a derived state in extant species, we use the results to investigate and discuss possible ecological trade-offs and associated fitness advantages. These may explain the hypothesized repeated loss of this trait. The frequent association between large seed size and desiccation sensitivity is also considered. [source] Conflicting selection pressures on seed size: evolutionary ecology of fruit size in a bird-dispersed tree, Olea europaeaJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2003J. M. Alcántara Abstract Recent evidence indicates that fruit size has evolved according to dispersers' size. This is hypothesized to result from a balance between factors favouring large seeds and dispersers setting the maximum fruit size. This hypothesis assumes that (1) the size of fruits that can be consumed by dispersers is limited, (2) fruit and seed size are positively correlated, and (3) the result of multiple selection pressures on seed size is positive. Our studies on the seed dispersal mutualism of Olea europaea have supported the first and second assumptions, but valid tests of the third assumption are still lacking. Here we confirm the third assumption. Using multiplicative fitness components, we show that conflicting selection pressures on seed size during and after dispersal reverse the negative pattern of selection exerted by dispersers. [source] PREDICTION OF MECHANICAL PROPERTIES OF CUMIN SEED USING ARTIFICIAL NEURAL NETWORKSJOURNAL OF TEXTURE STUDIES, Issue 1 2010M.H. SAIEDIRAD ABSTRACT In this paper, two artificial neural networks (ANNs) are applied to acquire the relationship between the mechanical properties and moisture content of cumin seed, using the data of quasi-static loading test. In establishing these relationship, the moisture content, seed size, loading rate and seed orientation were taken as the inputs of both models. The force and energy required for fracturing of cumin seed, under quasi-static loading were taken as the outputs of two models. The activation function in the output layer of models obeyed a linear output, whereas the activation function in the hidden layers were in the form of a sigmoid function. Adjusting ANN parameters such as learning rate and number of neurons and hidden layers affected the accuracy of force and energy prediction. Comparison of the predicted and experimented data showed that the ANN models used to predict the relationships of mechanical properties of cumin seed have a good learning precision and good generalization, because the root mean square errors of the predicated data by ANNs were rather low (4.6 and 7.7% for the force and energy, respectively). PRACTICAL APPLICATIONS Cumin seed is generally used as a food additive in the form of powder for imparting flavor to different food preparations and for a variety of medicinal properties. Physical properties of cumin seeds are essential for the design of equipment for handling, harvesting, aeration, drying, storing, grinding and processing. For powder preparation especially the fracture behavior of the seeds are essential. These properties are affected by numerous factors such as size, form and moisture content of the grain and deformation speed. A neural network model was developed that can be used to predict the relationships of mechanical properties. Artificial neural network models are powerful empirical models approach, which can be compared with mathematical models. [source] | |||||||||||||||||||||||||||||||