Effects of wind speed,underlying surface,and seed morphological traits on the secondary seed dispersal in the Tengger Desert,China

The maintenance of sand-fixing vegetation is important for the stability of artificial sand-fixing systems in which seed dispersal plays a key role.Based on field wind tunnel experiments using 11 common plant species on the southeastern edge of the Tengger Desert,China,we studied the secondary seed dispersal in the fixed and semi-fixed sand dunes as well as in the mobile dunes in order to understand the limitations of vegetation regeneration and the maintenance of its stability.Our results indicated that there were significant variations among the selected 11 plant species in the threshold of wind speed(TWS).The TWS of Caragana korshinskii was the highest among the 11 plant species,whereas that of Echinops gmelinii was the lowest.Seed morphological traits and underlying surface could generally explain the TWS.During the secondary seed dispersal processes,the proportions of seeds that did not disperse(no dispersal)and only dispersed over short distance(short-distance dispersal within the wind tunnel test section)were significantly higher than those of seeds that were buried(including lost seeds)and dispersed over long distance(long-distance dispersal beyond the wind tunnel test section).Compared with other habitats,the mobile dunes were the most difficult places for secondary seed dispersal.Buried seeds were the easiest to be found in the semi-fixed sand dunes,whereas fixed sand dunes were the best sites for seeds that dispersed over long distance.The results of linear mixed models showed that after controlling the dispersal distance,smaller and rounder seeds dispersed farther.Shape index and wind speed were the two significant influencing factors on the burial of seeds.The explanatory power of wind speed,underlying surface,and seed morphological traits on the seeds that did not disperse and dispersed over short distance was far greater than that on the seeds that were buried and dispersed over long distance,implying that the processes and mechanisms of burial and long-distance dispersal are more complex.In summary,most seeds in the study area either did not move,were buried,or dispersed over short distance,promoting local vegetation regeneration.

Impacts of snow on seed germination are independent of seed traits and plant ecological characteristics in a temperate desert of Central Asia

Seed germination profoundly impacts plant community composition within the plant life cycle.Snow is an important source of water for seed germination in the temperate deserts of Central Asia.Understanding how seed germination responds to variations in snow cover in relation to seed traits and plant ecological characteristics can help predict plant community sustainability and stability in Central Asia under a scenario climate change.This study investigated the seed germination of 35 plant species common to the Gurbantunggut Desert in Central Asia under the three snow treatments:(1)snow addition;(2)ambient snow;and(3)snow removal.Two-way analysis of variance(ANOVA)tests were performed to assess interactions among the impacts of snow treatments,seed traits and plant ecological characteristics on seed germination.Phylogenetic generalized least-squares(PGLS)model was used to test the relationships between seed traits and seed germination.The results demonstrated that snow variations had no significant impacts on seed germination overall.Seed germination under the snow addition treatment was similar with that under the ambient snow treatment,irrespective of seed traits and plant ecological characteristics.Snow removal only had negative impacts on seed germination for certain groups of seed traits and plant ecological characteristics.Seed mass positively affected seed germination,showing a linear increase of arcsin square root-transformed seed germination with log-transformed seed mass.Seed shape also profoundly impacted seed germination,with a higher germination percentage for elongated and flat seeds.Seed germination differed under different plant life forms,with semi-shrub species showing a significantly higher germination percentage.Most importantly,although snow treatments,seed traits and plant ecological characteristics had no interactive effects on seed germination overall,some negative impacts from the snow removal treatment were detected when seeds were categorized on the basis of seed mass and shape.This result suggests that variations of snow cover may change plant community composition in this temperate desert due to their impacts on seed germination.

Variability in seed traits and genetic divergence in a clonal seed orchard of Dalbergia sissoo Roxb.

The variations in seed and pod traits, genetic superiority and genetic divergence were evaluated for a Clonal Seed Orchard （CSO） of Dalbergia sissoo Roxb. at Bithmera, India consisting of 20 clones from different agro-climatic conditions of four northern states （Uttar Pradesh, Uttarakhand, Haryana and Rajasthan）. The seeds and pods of various clones in the orchard exhibited significant variability in size, weight and other characters. Significant positive correlations were observed between seed length and seed width （p〈0.05）, seed length and sccd thickness （p〈0.01）, seed length and seed weight （p〈0.01）, seed thickness and seed weight （p〈0.01）, seed length and germination value （p〈0.05）. The ge- netic parameters for seed and pod traits also showed a wide range of variations in the orchard. Heritability values were found to be over 50 percent for most of ~e seed and pod traits. Seed weight, seed length and seed thickness showed high heritability values coupled with maximum genetic gain for these characters. Ward＇s minimum variance dendrogram of clones of D. sissoo showed three distinct clusters; cluster I was the largest with 12 better clones whereas cluster 2 and 3 consisting of seven moderate clones and one poor clone, respectively. Mean cluster values showed sufficient variation among the clusters for seed weight, germina- tion value and seed length. The possible hybridization between best clones of cluster I to the disease resistant clone of cluster 2 （resistant against deadly Gandoderma lucidum root rot disease of D. sissoo） is also suggested for further breeding programmes of the species. The deploy- ment of clone 194 （better performed and disease resistant） is also rec- ommended in future plantation programmes of D. sissoo in northern India.

The effects of grain texture and phenotypic traits on the thin-layer drying rate in maize(Zea mays L.) inbred lines

To explore the relation of maize grain texture and phenotypic traits with grain thin-layer drying rate,we observed the ultra-structure of maize grain,and tested three traits about the maize grain texture and four phenotypic traits.The vitreous part percentage was different（P〈0.05） among different maize inbred lines.There was a significant relationship between the drying rate with grain texture and phenotypic traits.Main factors that influenced the drying rate were different during different drying stages.New results observed that empirical constants（k and N） in drying equation were different for seed of the 30 inbred lines of maize.The k of simplified diffusion equation and N of page equation were significantly influenced by both grain texture and phenotypic traits.These results could be used as guideline parameters for drying maize seeds having different grain characteristics during different drying stages.

Identification of Quantitative Trait Loci Controlling Seed Physical and Nutrient Traits in Cotton

Cotton(Gossypium spp.) is the leading fiber crop,and an important source of the important edible oil and protein meals in the world.Complex genetics and strong environmental effects hinder

Variation in cone and seed characters in blue pine (Pinus wallichiana) across natural distribution in western Himalayas

We analyzed 17 seed sources （seed stands） ofPinus wallichiana for variations present in cone and seed characters, scattered over natural distribution in north-west Himalayan states （Uttarakhand and Himachal Pradesh） of India. The significant variations were observed in cone weight, cone length, cone width, seed length, seed width, seed weight, seed germination, radicle length, and plumule length among different seed sources of the species. Significant positive correlation between seed weight, cone weight and cone width showed that seed weight in the species depend more on the cone size. Seed germination was also positively correlated with seed weight, cone weight and radicle length in the study. The estimates of variability with regard to genetic parameters for seed weight, seed germination, cone length, cone width, cone weight showed wide range of variation in the study. Seed weight showed high heritability values coupled with maximum genetic gain. Traits with such values indicate presence of good amount of heritable additive components and are under strong genetic control. The findings of the study revealed that seed sources expressed both phenotypic and genotypic differences in the seed and cone traits which might be due to the differences in genetic make up of various seed sources and environmental factors i,e. genotypic and environmental interaction, The study suggests that the seed weight should be given the top priority for the further improvement of this species.

Variability in cone,seed and seedling characteristics of Pinus kesiya Royle ex.Gordon

Investigations were made to determine the nature and extent of variations present for 10 morphological characters of cone,seed and seedlings of 17 plus trees（PTs）of Pinus kesiya growing in eastern Himalayas（Meghalaya state） of India.The significant variations has been observed in cone weight,cone length,cone diameter,seed length,seed diameter,seed weight,number of seeds per cone,seed germination,seedling height and seedling collar diameter among different PTs of the species.Significant positive correlation（p ／ 0.01） between seed weight,cone length and cone diameter showed that seed weight in P.kesiya depend more on the cone size.Seed germination is found positively correlated（p ／ 0.01） with seed weight,seed diameter,cone size and number of seeds per cone in the study.Among geographical factors,latitude and altitude are found positively correlated（p ／ 0.05） with cone weight and seed diameter,respectively.The genetic parameters for seed,cone and seedlings of PTs of P.kesiya also showed a wide range of variability in terms of variance,coefficient of variability,broad sense heritability,genetic advance and genetic gain.Seed weight,seeds per cone and seedling diameter showed high heritability values（[75） coupled with maximum genetic gain.Traits with such values indicate the presence of good amount of heritable additive components and are under strong genetic control.The findings of the study revealed that PTs expressed both phenotypic and genotypic differences in the seed,cone and seedling characters,which may be attributed to the differences in genetic makeup of various PTs and environmental factors i.e.genotypic and environmental interaction.The presence of high variability in P.kesiya PTs for different characters provide further opportunities to improve the population in subsequent generations so as to establish this species as an important timber tree to be grown on less fertile and degraded soils in its distributional ranges.

Trait-mediated seed predation, dispersal and survival among frugivore-dispersed plants in a fragmented subtropical forest, Southwest China

By tracking the fate of individual seeds from 6 frugivore-dispersed plants with contrasting seed traits in a frag­mented subtropical forest in Southwest China,we explored how rodent seed predation and hoarding were influ­enced by seed traits such as seed size,seed coat hardness and seed profitability.Post-dispersal seed fates var­ied significantly among the 6 seed species and 3 patterns were witnessed:large-seeded species with a hard seed coat(i.e.Choerospoadias axillaries and Diospyros kaki var.silvestris)had more seeds removed,cached and then surviving at caches,and they also had fewer seeds predated but a higher proportion of seeds surviving at the source;medium-sized species with higher profitability and thinner seed coat(i.e.Phoebe zhennan and Pa­dus braohypoda)were first harvested and had the lowest probability of seeds surviving either at the source or at caches due to higher predation before or after removal;and small-seeded species with lower profitability(i.e.Elaeocarpus japonicas and Cornus controversa)had the highest probability of seeds surviving at the source but the lowest probability of seeds surviving at caches due to lower predation at the source and lower hoarding at caches.Our study indicates that patterns of seed predation,dispersal and survival among frugivore-dispersed plants are highly determined by seed traits such as seed size,seed defense and seed profitability due to selective predation and hoarding by seed-eating rodents.Therefore,trait-mediated seed predation,dispersal and survival via seed-eating rodents can largely affect population and community dynamics of frugivore-dispersed plants in fragmented forests.

Seed traits and taxonomic relationships determine the occurrence of mutualisms versus seed predation in a tropical forest rodent and seed dispersal system

Although many studies have been carried out on plant-animal mutualistic assemblages,the roles of function­al traits and taxonomy in determining both whether interactions involve mutualisms or predation and the struc­ture of such assemblages are unclear.We used semi-natural enclosures to quantitatively assess the interaction strengths between seeds of 8 sympatric tree species and 4 rodent species in a tropical forest in Xishuangban­na,Yunnan,Southwest China.We found 2 clusters of species in the seed-rodent network represented by 2 gen­era in the Fagaceae(Castanopsis,Lithocarpus).Compared to seeds of 3 Castanopsis species,seeds with heavy weight,hard coat or caloric content(including 3 Lithocarpus species)were eaten less and more frequently hoarded by rodents.In turn,hoarded seeds showed less predation and more mutualism with rodents.Our results suggest that seed traits significantly affected the hoarding behavior of rodents,and,consequently,the occurrence of mutualisms and predation as well as assemblage structure in the plant-animal seed dispersal system.Taxo­nomically-related species with similar seed traits as functional groups belong to the same substructures in the assemblage.Our results indicate that both seed traits and taxonomic relationships may simplify thinking about seed dispersal systems by helping to elucidate whether interactions are likely to be dominated by predation or mutualism.

Seed traits and rodent community interact to determine seed fate:evidence from both enclosure and field experiments

Animal-mediated seed dispersal is an important ecological process in which a strong mutualism between animals and plants can arise.However,few studies have examined how a community of potential seed dispersers interacts with sympatric seed trees.We employed a series of experiments in the Qinling Mountains in both semi-natural enclosure and the field to assess the interactions among 3 sympatric rodent species and 3 Fagaceae tree seeds.Seed traits all showed similar tannin levels but markedly different physical traits and nutritional contents.We found that seeds with heavy weight,thick coat,and high nutritional contents were less likely to be eaten in situ but more often to be eaten after dispersal or hoarded by rodents.These results support both the handling time hypothesis and the high nutrition hypothesis.Surprisingly,we also found that rodents,maybe,preferred to consume seeds with low levels of crude fiber in situ,and to harvest and hoard those with high levels of crude fiber for later consumption.The sympatric rodent species,Cansumys canus,the largest rodent in our study,harvested and hoarded more Quercus variabilis seeds with high physical and nutritional traits,while Apodemus draco,the smallest rodent,harvested more Q.serrata seeds with low physical and nutritional traits,and Niviventer confucianus harvested and hoarded more Q.aliena seeds with medium physical and nutritional traits.Our study demonstrates that different seed traits play different roles in influencing the seed fate and the shaping of mutualism and predation interactions within a community of rodent species.

The effects of seed detectability and seed traits on hoarding preference of two rodent species

Seed traits play an important role in affecting seed preference and hoarding behaviors of small rodents.Despite greatly affected by seed traits,seed detectability of competitors represents pilfering risks and may also modify seed hoarding preference of animals.However,whether seed traits and seed detectability show consistent effects on seed hoarding preference of animals remain largely unknown.Here,we explored how seed traits and seed detectability correlate with seed hoarding preference of Leopoldamys edwardsi and Apodemus chevrieri in a subtropical forest.Despite the effects of seed coat thickness and caloric value on hoarding preference of L.edwardsi,we detected no significant effects of other seed traits on hording preference of the 2 rodent species.There was no correlation between larder-hoarding preference and inter-or intra-specific seed detectability of L.edwardsi;however,seed detectability of L.edwardsi was negatively correlated with its own scatter-hoarding preference.Although scatter-hoarding preference of A.chevrieri was not correlated with inter-and intra-specific seed detectability,larder-hoarding preference of A.chevrieri was positively correlated with intra-specific seed detectability.Our study may provide evidence that intra-specific seed detectability rather than seed traits and inter-specific pilfering risks play an important role in modifying seed hoarding preference of rodents.

Index selection on seed traits under direct,cytoplasmic and maternal effects in multiple environments

Crop seeds are important sources of protein, oil, and carbohydrates for food, animal feeds, and industrial products. Recently, much attention has been paid to quality and functional properties of crop seeds. However, seed traits possess some distinct genetic characteristics in comparison with plant traits, which increase the difficulty of genetically improving these traits. In this study, diallel analysis for seed models with genotype by environment interaction （GE） effect was applied to estimate the variance-covariance components of seed traits. Mixed linear model approaches were used to estimate the genetic covariances between pair-wise seed and plant traits. The breeding values （BV） were divided into two categories for the seed models. The first category of BV was defined as the combination of direct additive, cytoplasmic, and maternal additive effects, which should be utilized for selecting stable cultivars over multi-environments. The three genetic effects, together with their GE interaction, were included in the second category of BV for selecting special lines to be grown in specific ecosystems. Accordingly, two types of selection indices for seed traits, i.e., general selection index and interaction selection index, were developed and constructed on the first and the second category BV, respectively. These proposed selection indices can be applied to solve the difficult task of simultaneously improving multiple seed traits in various environments. Data of crop seeds with regard to four seed traits and four yield traits based on the modified diallel crosses in Upland cotton （Gossypium hirsutum L.） were used as an example for demonstrating the proposed methodology.

Image analysis of Moroccan carob seeds(Ceratonia siliqua L.)revealed substantial intraspecific variations depending on climate and geographic origin

Background:The carob tree(Ceratonia siliqua L.)is one of the most iconic tree species of the Mediterranean region,with valuable economic,ecological and cultural value.Carob has been exploited around the Mediterranean region since antiquity and has been regarded as an important component of natural habitats and traditional agroecosystems.Several studies have focused on its morphological,biochemical,and genetic diversity.However,less is known about the intraspecific variation of seed traits.In this regard,and as an overall objective,we intend to evaluate the amplitude and the expression of intraspecific variations of carob seed traits at different ecological scales ranging from individual trees to different geographical landscapes.In addition,we investigated how the climate along the study area affects the extent of carob seed variability.Using image analysis techniques,we measured seven traits related to the size and the shape of 1740 seeds collected from 18 populations of spontaneous C.siliqua distributed along a latitudinal transect in Morocco under different bioclimatic conditions.Results:The morphometric analysis of carob seed showed the effectiveness of adopted approach to highlight the amount and the amplitude of intraspecific variation according to geographic and climatic factors.Seed trait analysis revealed high intraspecific variability,explained by differences between and among carob populations and geographic zones.Seed area,perimeter,length,and width showed the largest variability between geographic zones.However,circularity,aspect ratio,and seed roundness showed higher variability at the tree level.Finally,our results show that seed traits vary depending on altitude and climate condition.Conclusions:Revealing the amount and the structure of intraspecific traits variability of carob seed provides interesting insights to understand the mechanisms underlying trees adaptation to various environmental and ecological conditions.Therefore,intraspecific variation of seed traits should be integrated into trait‑based functional ecology to assess plant species responses to environmental changes.

Seed value influences cache pilfering rates by desert rodents

Some rodents gather and store seeds.How many seeds they gather and how they treat those seeds is largely determined by seed traits such as mass,nutrient content,hardness of the seed coat,presence of secondary compounds,and germination schedule.Through their consumption and dispersal of seeds,rodents act as agents of natural selection on seed traits,and those traits influence how rodents forage.Many seeds that are scatter-hoarded by rodents are pilfered,or stolen,by other rodents,and seed traits also likely influence pilfering rates and seed fates of pilfered seeds.To clarify coevolutionary relationships between rodents and the plants that they disperse,one needs to understand the role of seed traits in rodent foraging decisions.We compared how the seeds of 4 species of plants that are dispersed by scatter-hoarding animals and that differ in value(singleleaf piñon pine,Pinus monophylla;desert peach,Prunus andersonii;antelope bitterbrush,Purshia tridentata;Utah juniper,Juniperus osteosperma)were pilfered and recached by rodents.One hundred artificial caches of the 4 seed species(25 per species)were prepared,and removal by rodents was monitored.Rodents pilfered high-value seeds more rapidly than the other seeds.Desert peach seeds,which contain toxic secondary compounds,were more frequently recached.Relatively low value seeds like Utah juniper and antelope bitterbrush were pil-fered more slowly and were sometimes left at cache sites,and seeds of the latter species were transported shorter distances to new cache sites.The background density of seeds also appeared to influence the relative value of seeds.

Seasonal distribution of increased precipitation in maternal environments influences offspring performance of Potentilla tanacetifolia in a temperate steppe ecosystem

Aims Precipitation is predicted to increase in arid and semiarid regions under climate change,with greater changes in intra-and interannual distribution in the future.As a major limiting factor in these regions,changes in precipitation undoubtedly influence plant growth and productivity.However,how the temporal shifts in pre-cipitation will impact plant populations are uncertain.Methods A 3-year field experiment and a greenhouse experiment were conducted in a temperate grassland in northern China to examine the impacts of seasonal(spring and summer)increased precipitation on offspring performance of a common species,Potentilla tanacetifolia.Important Findings Our results showed that the amounts and timing of increased precipitation both played important roles in regulating offspring performance of P.tanacetifolia in the temperate steppe ecosystem.Increased precipitation in spring at maternal stage stimulated seed production,germination percentage and seedling biomass,whereas increased precipitation in summer at maternal stage stimulated seedling biomass.The timing of increased precipitation influenced seed attributes,whereas the amount of increased precipitation influenced offspring seedling biomass.Our results indicate that population development of P.tanacetifolia may be underestimated under future increased precipitation regime,if the transgenerational effect is not taken into account.

Cultivated walnut trees showed earlier but not final advantage over its wild relatives in competing for seed dispersers

Little is known about seeding regeneration of cultivated trees compared to wild relatives in areas where seed dispersers are shared.Here,we investigated the differences in seed fates of cultivated walnut(Juglans regia)and wild Manchurian walnut(Juglans mandshurica)trees under rodent predation and dispersal.J.regia seeds have higher nutritional value(large size,mass and kernel mass)and lower mechanical defensiveness(thin endocarp)than J.mandshurica seeds.We tracked seeds of J.regia and J.mandshurica under both enclosure and field conditions to assess differences in competing for seed dispersers of the two co-occurring tree species of the same genus.We found that rodents preferred to harvest,eat and scatter-hoard seeds of J.regia as compared to those of J.mandshurica.Seeds of J.regia were removed and scatter-hoarded faster than those of J.mandshurica.Caches of J.regia were more likely to be rediscovered by rodents than those of J.mandshurica.These results suggest that J.regia showed earlier dispersal fitness but not the ultimate dispersal fitness over J.mandshurica in seeding regeneration under rodent mediation,implying that J.regia has little effect on seeding regeneration of J.mandshurica in the field.The effects of seed traits on seed dispersal fitness may vary at different dispersal stages under animal mediation.