Density Of Seeds Research Articles

The Similarity between Species Composition of Vegetation and Soil Seed Bank of Grasslands in Inner Mongolia, China: Implications for the Asymmetric Response to Precipitation.

The asymmetric response of productivity to precipitation was recently proposed as an early warning signal for the shifts in temperate grassland function in China. It was hypothesized that the asymmetry was influenced by the increased growth of the newly emerged seedlings from the soil seed bank. Therefore, the seed density in the soil seed bank and the similarity between species composition of the vegetation and the soil seed bank should be maximized where asymmetry was maximized. However, this knowledge was still limited and unconfirmed. In this study, the desert steppe, typical steppe and the transition zone between them (with the highest asymmetry) were selected for studying the similarity index in both 2018 (dry year) and 2019 (wet year). Plant species composition was monitored in situ using an unmanned aerial vehicle. Soil seed bank samples were collected, and the seed bank density and species composition were then examined and identified in the laboratory. Results showed that: (1) The variation in vegetation species richness between the two years was the highest (41%) in the transition zone (p < 0.05), while it was only 7% and 13% for the desert steppe and typical steppe, respectively. The presence of herbaceous species mainly caused the differences in variation among three grassland types. (2) Seed density was the highest in the transition zone (114 seeds/m2 and 68 seeds/m2 in the transient and persistent soil seed bank, respectively) (p < 0.05). Additionally, herbaceous species were the main components of the soil seed bank. (3) The similarity index was the highest in the transition zone (p < 0.05), with 38%/44% and 33%/44% for the transient/persistent soil seed bank in 2018 and 2019, respectively. Our study demonstrated that variation in vegetation species composition was very similar to the composition of the seeds accumulated in the soil seed bank. These results warrant further investigation for the mechanism of asymmetric response of productivity to precipitation.

A Non-Invasive Approach in the Assessment of Stress Phenomena and Impairment Values in Pea Seeds Caused by Pea Weevil.

Pea (Pisum sativum L.) is an important leguminous plant worldwide, in which pests trigger significant damage every year. One of the most important pest is pea weevil (Bruchus pisorum, L) which causes covert damage in crops. In the present study, our aim was to obtain precise information pertaining to the extent and the nature of damage in pea caused by B. pisorum by means of non-invasive imaging methods. The infested pea samples were analysed by an infrared thermometer and a bioluminescence plant imaging system as well as a computer tomograph under laboratory conditions. The calculated weight of organic matter destroyed by the developing larvae was 36.46%. The changing of RGB (red, blue, green) codes obtained through thermal imaging and the CPS (counts per second) values originating from bioluminescence imaging in infested samples were statistically verifiable. According to our CT assay, the damage caused by B. pisorum changed the tissue density, volume and shape of the pea seeds by the end of the development of the pest. The results of thermal and bioluminescence imaging contribute to a better understanding of the internal chemical processes and the CT analysis helps to understand the alteration trends of the inner structure of seeds caused by this pest.

Effects of Different Seed Density, Temperature and Fertilization Applications on Some Growth Parameters in Soilless Roll Sod Production

This study was conducted to determine the effects of different seed density, temperature, and fertilization applications on some growth parameters in the soilless roll sod production. When research results are evaluated by taking into account the highest overall appearance and green plant yield values together, it is observed that 75 g m-2 seed density and 25 and 30°C temperature applications are in recommendable qualification. For future research to be conducted on the subject, it is considered useful to include different growing times and land applications in the studies.

Effect of Lentil’s Variety and Cultural Farming System on Nutritional Value and Physicochemical Sensory Properties as Related to Human Daily Coverage

The aim of this study is to determine if there is any influence of lentil variety and environment of cultivation in the chemical composition of seeds originating from organic and conventional farming systems. Particularly, an evaluation was made on the physicochemical properties of three lentil cultivars (‘Thessalia’, ‘Dimitra’, ‘Samos’) and also the effect of farming system towards the composition of seeds to be assessed for discovering the tendency which specific cultivar or farming system are most preferable for the consumers. For the evaluation of the physicochemical properties of lentil seeds: (a) Seed density, (b) Hydration coefficient, (c) Swelling coefficient, (d) pH and (e) Content in macro- and micronutrients (total nitrogen, phosphorus, potassium, calcium, magnesium, iron, zinc, manganese, and boron), were estimated. Multivariate statistical analysis was applied for every characteristic in order to determine similarities/ differences among the cultivars in both organic and conventional farming systems. In addition, Analysis of Variance (ANOVA) and Principal Component Analysis (PCA) were conducted. Regarding the three cultivars under evaluation, cv. ‘Dimitra’ is superior especially in the organic environment, followed by cv. ‘Thessalia’, whose nutritional value increases under organic farming conditions. While ‘Samos’ exhibited a slightly better performance under conventional conditions. Based on the results of this research, the interaction between the lentil cultivar and the cultivating environment can influence the nutritional value and the physicochemical properties of lentil’s seeds.

MOISTURE-DEPENDENT PHYSICAL PROPERTIES OF MEDICAL TINY SEEDS: PART B: SUMMER SAVORY (SATUREJA HORTENSIS L.), BASIL (OCIMUM BASILICUM L.), CRESS (LEPIDIUM SATIVUM L.), AND AJOWAN (CARUM COPTICUM L.)

One of the most critical challenges of determining tiny seeds’ engineering properties is their dimensions. In the present study, a method based on digital image processing was employed to investigate the moisture content’s effect on geometric properties of summer savory, basil, cress, and ajowan seeds. Also, the gravimetrical and frictional properties of the seeds were measured. Gamma, Generalized Extreme Value, and Weibull distributions were used to model the probability frequency distribution of the seeds’ length, width, and thickness. This research indicated that the application of the image processing technique could be an excellent method to measure dimensional parameters of tiny seeds. Results showed that, with an increasing moisture content of seeds, the 1000-seed mass increased for basil, cress, and ajowan seeds; but, summer savory seeds showed that increasing-decreasing trend. For all four plant spices, increasing moisture content will result in the bulk density decrement. The particle density of summer savory, basil, and cress seeds decreased due to moisture content increment. However, the particle density of ajowan seeds increased with increasing moisture content. Results of measuring the angle of friction on iron, wood, and galvanized surfaces showed that, in most cases, the angle of friction increased by increasing moisture content. Also, except for the filling angle of repose of summer savory, increasing trends were observed for the emptying and filling angle of repose due to moisture content increment.

Seagrass seed bank spatial structure and function following a large-scale decline

We examined the spatial structure (distribution, density) and function (viability) of the seagrass sediment seed bank, the storage of viable propagules (e.g. seeds, tubers, diaspores) in the sediment over time,in the northern Great Barrier Reef World Heritage Area in Cairns, Queensland, following a large-scale decline in seagrass area. A spatially explicit seagrass seed bank analysis was paired with a long-term annual assessment of seagrass distribution to assess seed bank spatial patterns and their relationship with the recovery and presence of seagrass, and water depth. Four years post-decline, the seed bank contained Zostera muelleri, Halodule uninervis, Halophila ovalis and Cymodocea serrulata seeds. Seed banks reflected adjacent meadow community composition; however, the density of seeds for all recorded species was significantly lower than analogous seagrass populations, indicating a reduction in the capacity for recovery from the seed bank. A spatial structure existed in both the total (viable + non-viable) and viable seed bank, and distance between seed clusters ranged from 50-550 m depending on species and seed type. Observed patterns in clustering may be explained by variation in water depth and the past distribution of seagrass in these meadows. These results demonstrate that the distribution of seagrass seeds within the seed bank, which directly influences the natural recovery of seagrass communities, is not uniform across species and may result in patchy recovery of the meadows. Therefore, the resilience provided by the seed bank in seagrass communities should not be viewed as a static level of insurance for the entire meadow, but rather as dynamic and species-specific, with variability over both space and time.

Physical, chemical and microbiological characterization of cupuassu seed during fermentation

The cupuassu’s seeds are similar to cocoa, being possible to apply fermentative techniques used to obtain nibs and cupulate. The aim of this work to study the physicochemical transformations during the cupuassu´s seeds fermentation. For this purpose, frozen seeds from a pulp processing industry were fermented in three batches of 20 kg for seven days at room temperature. During the fermentation process, seed mass temperature, dimensions, density and composition of the kernels, color indexes (L*, C* and H*), microbiological analyzis (mesophiles, molds and yeasts), cut-proof, physicochemical analyzis (pH, acidity and glucose reducing sugars and non sucrose reduction) and centesimal composition (ashes, lipids, proteins and carbohydrates) were analyzed from triplicates. The results were expressed as dry basis. During the fermentations, the great temperatures were reached. The maximus were 43,44 and 47 ºC in three fermentations. It was observed during the fermentation process: seed darkening (L*) and color intensity reduction (Chroma), pH increase, sugar reduction and acidity reduction. The ash, lipid and protein contents were not significantly influenced by the fermentation time. According to the cut test, the kernels of 3rd fermentation, whose maximum temperature was higher, were classified as type 2 and the others as type 3. The values of apparent density, dimensions, mass and composition of seeds demonstrated that during the fermentation there was a decrease in volume with a higher proportion of cotyledon compared to testa. There was an increase in counts of total mesophiles aerobic microorganisms, molds and yeasts, during the fermentative process.

Morphological and Biochemical Characterization of Wild Hop (Humulus lupulus L.) Populations from Banja Luka Area (Bosnia and Herzegovina)

This study aims to do a morphological and biochemical characterization of selected wild hop populations from the Banja Luka region, as plant material with potential value for introduction into plant selection. Female inflorescences (cones) from seven populations (DKH3, DKH5, DKH6, DKH8, DKH9, DKH10, and DKH11) were sampled in 2018 and 2019. Hop cones were collected in October 2018 and 2019 for morphological characterization, when 50 cones per population were analyzed, and also the cones were collected in mid-September in 2019 for biochemical characterization. Morphological parameters were carried out for: cone length (cm), number of nodes per cone spindle, cone density, and number of seeds per cone, all important agronomic characters in hop production. Also, 27 components of essential oil and 6 components of hop resins were analyzed. Statistical analysis of morphological characteristics was performed by factorial analysis of variance (year × population), and the significance of individual differences was determined by LSD test. The grouping of examined hop populations according to the manifested morphological characteristics was performed by cluster analysis. Statistical analysis for biochemical characteristics was performed by analysis of variance, and the significance of the differences was tested by Tukey’s statistical test. In order to determine similarities between different population multivariant statistical method Principal component analysis (PCA) was applied. According to morphological and biochemical analysis, DKH6 hop population is singled out as the most valuable for hop breeding.

Effect of Seeding Density on Mat-Type Seedling Quality for Mechanical Transplanting in Dry Season Rice

Rice transplanting with a transplanter is a cost-effective process. Due to labor shortages during the peak time of rice transplanting, it is a promising technology in Bangladesh. However, the high-quality mat-type seedling is a prerequisite factor for mechanical transplanting. The experiments were conducted at three different locations (Gazipur, Tangail, and Rangpur) during the dry season (Boro)/2019-20 to determine the best seeding density for high-quality mat-type seedlings to be prepared for mechanical rice transplanters. The effects of seeding rate on seedling quality such as survival rate, seedling strength, stem thickness of newly released boro rice varieties BRRI dhan86, BRRI dhan89, and BRRI dhan92 were studied using four seeding rates (130, 140, 150, 160 g/tray). Results revealed that BRRI dhan92 showed quick seedling emergence compared to BRRI dhan89 and BRRI dhan86. Seedling mortality was found the lowest BRRI dhan92 while the highest in BRRI dhan86. 25 - 30 days old seedling was found suitable for mechanical transplanting in terms of seedling mortality. Seedling height increased with the increase in seed density. BRRI dhan92 showed the highest stem thickness followed by BRRI dhan89 and BRRI dhan86 with seed rate 150 - 160 g per tray. The suitable seeding rate (150 - 160 g/tray) for the studied varieties was found better for raising mat-type seedlings suitable for mechanical transplanting, which could coordinate the production of larger population growth and higher harvest index to achieve high grain yield.

The effect of herbicides on winter false flax (Camelina sativa (L.) Crantz.)

The purpose of the research was to determine the effect of herbicides on winter false flax and to identify the preparation that does not effect negatively on crop plants. The research was carried out in 20182020 at V.S. Pustovoit All-Russian Research Institute of Oil Crops. The experiment scheme included herbicides with active ingredients (a.i.), which effectively decreased the number of weeds on the plots. The effectiveness of the preparations was more than 70% for different types of weeds. However, the variants with the application of preparations with a.i. clopyralid 300 g/l, S-Metolachlor 960 g/l, ethametsulfuronmethyl 750 g/kg significantly decreased the plant density (by 18-32 pcs/m2) and seed yield (by 0.33-0.52 t/ha) of false flax in comparison with the control. The oil content of seeds was significantly decreased in the variants with the herbicides with a.i. S-Metolachlor 960 g/l with the application rate of 1.6 l/ha and ethametsulfuron-methyl 750 g/kg (by 1.2-1.5 %). In other variants, the oil content of false flax seeds differed from the control insignificantly (by 0.3-0.4 %). It has been established that the preparation with a.i. quinmerac 83 g/l + metazachlor 333 g/l with the application rate of 2.0 or 2.5 l/ha should be applied to decrease the number of weeds in the sowings of winter false flax in the central zone of the Krasnodar region. This preparation, without having a toxic effect, increases the yield by 0.15-0.17 t/ha and does not decrease the plant density and oil content of false flax seeds.

Experimental study in microcosms of the effect of fire on the characteristic vegetation of Mediterranean temporary ponds / Étude expérimentale en microcosmes de l’effet du feu sur la végétation caractéristique des mares temporaires méditerranéennes

Fire is an important disturbance factor of ecosystems. Its impact on temporary ponds remains poorly documented. In Morocco, temporary ponds are numerous and mostly found in forested and agricultural environment. Forest fire has been increasingly frequent over the last years eventually spreading to the temporary pools. In addition, some farmers light fire to get rid of the biomass of crop residues. No assessment of the impact of fire on the plant biodiversity of temporary ponds was made. We tested the impact of fire on soil samples in an experiment in controlled conditions. Soil samples were taken from five ponds in the Middle Atlas divided into four series of 25 samples each. The first series served as a control while those of the 2nd, 3rd and 4th series were subjected respectively to a blowtorch flame sent for 30, 120 and 600 seconds. We measured the temperature of the soil surface for each treatment after fire using an infrared thermometer. We put all soil samples in germination conditions by watering them daily. During the second year, we manually disturbed the soil samples and then germinated them by watering them daily. Unlike low-intensity fires (fires of agricultural land), high-intensity fires (forest fires) significantly reduced the total density of seeds, those of annuals and aquatic annuals, as well as the species richness of the same groups. The effect of fire also varied according to the species and the duration of exposure. Natural restoration of the vegetation of the temporary ponds even after an intense fire is still possible but probably slow. Improved environmental conditions after fire and the presence in the soil of a long-lived seed bank are relevant indicators of restoration success.

Impact of organic substance on growth attributes of mat type rice seedlings in the trays for machine transplanting

Rice seedling for mechanical transplanting must fulfill the prerequisites of guideline seedling block with uniform density of seedlings and between bending pulls for rolling. The present study was carried out at the Farm Power and Machinery Department, Sylhet Agricultural University, Sylhet during Boro season/2018-19 with the objective to assess the impact of organic substance on agronomic attributes of mat type rice seedling. The seedling was raised on plastic rigid tray utilizing sandy clay loam (SCL) and sandy clay (SC) soil blending with the organic fertilizer of cow-dung (CD), rice bran (RB), rice husk (RH) and tea wastage (TW) at the rate of 0.0, 5, 10, 15 and 20%, respectively. Averaged across the rate of soil mixture, 5 to 15% of CD and RB with the both types of soil gave higher seedling height, leaf length and stem length while 20% of CD and TW also showed better result for number of leaves and stem thickness. Considering all parameters, 15 to 20% rice husk and tea wastage mixed with the sandy clay loam soil and 10 to 15% with the sandy loam soil gave good result. Be that as it may, seedling quality differed among the natural composts with the two kinds of soil more or less like CD &gt; RB &gt; TW &gt; RH. Water requirement in the SC soil was more compared to SCL soil. It was observed that crack was formed on the sandy clay soil in tray. For both types of soil, the density of seeds in the mat at the rate of 6-7 seeds cm-2 was found at 80% of soil mixture along with rice bran. The findings of the study could be promoted widely in farmer’s field to raise better quality of mat type seedling for better performance of the mechanical rice transplanter which ultimately leads to getting better rice yield.

Neighbour effects do not always show consistent patterns, contrast of seed trait matters: evidence from a seed-rodent mutualism study

Coexisting plant species often share the same animal mutualists and enemies. The selection preference of an animal on a focal individual is not only directly affected by the focal individual’s intrinsic traits, but also indirectly affected by conspecific or interspecific neighbouring individuals. Many studies often show inconsistent neighbour effects by comparison of the results between the presence and absence of neighbours, without considering the contrasting functional traits between the focal individual and the neighbours. Rodent-seed interaction that is ubiquitous in many ecosystems was selected to test the neighbour effect by using artificial seeds with different tannin contents, a vital seed trait that directly influences rodent foraging preference. I compared the seed predation and dispersal preference of rodents by monitoring the fate of 1920 artificial seeds with different absolute tannin contents (from 0 to 25%) among three categories of neighbouring seeds with tannin contents of 0%, 10% and 25%, respectively. Obvious neighbour effects were observed, although the magnitude and direction of the effects differed among different processes of scatter-hoarding behaviour. Furthermore, the neighbour effect did not show a consistent pattern among seeds with different tannin contents. Our results strongly suggested that the neighbour effects of coexisting species should be considered when evaluating the foraging preferences of animal mutualists/predators upon a specific plant species. The contrasting functional traits between focal plants and neighbouring individuals should be considered when studying neighbour effects. By using the artificial seed study system, I found that the contrast of tannin content could explain the inconsistent patterns of neighbour effects (i.e. the fate of a specific seed is influenced by its neighbouring seeds) among different seeds. In natural forest systems, plant seeds have a diverse array of traits, all of which markedly affect rodent foraging behaviour. Furthermore, a large spatio-temporal variation in seed production among species may result in a distinct variation in the relative densities of different seeds, which in turn may lead to even more complex neighbour effects at the whole forest community level. Our results strongly suggested that the neighbour effects of coexisting species of seeds should be considered when evaluating seed dispersal and predation of a specific species. The contrasting seed traits between focal plants and neighbouring individuals should be considered when studying neighbour effects.

Some physical properties of lentil seeds affected by harvest time

Abstract: The physical properties and the hardness of lentil seeds, which can also be affected by harvest times, are very important variables in the designing and adjustment of machineries used during harvest, handling and other processes. The objective of this study is to determine the effects of different harvest times on some physical and mechanical properties of lentil seeds. A field experiment was conducted at six harvest times including the harvesting at physiological maturity (H1) and 5, 10, 15, 20 and 25 days after physiological maturity (H2, H3, H4, H5 and H6, respectively). The variables determined were moisture content, diameter, thickness, sphericity, seed mass, bulk density, true density, porosity and hardness of lentil seeds. It was found that seed moisture content, seed dimensions, seed mass and bulk density decreased with delayed harvest time. However, sphericity, true density, porosity and hardness of lentil seeds increased with increased harvest time.

Natural regeneration triggers compositional and functional shifts in soil seed banks

Secondary forests emerging during traditional shifting cultivation practices are increasingly recognized for their fulfillment of ecosystem services and mitigation potential of climate change and biodiversity losses. The soil seed bank as a recruit reservoir is a limiting factor for natural forest regeneration of such secondary forests and is decisive for the formation and restitution of the post-disturbance community. The aim of this study was to compare the composition of the soil seed bank along a natural regeneration chronosequence from the Caxiuanã National Forest, eastern Amazon, including old-growth reference sites. We sampled standing vegetation, soil properties and soil seed banks and compared the density and species richness of different life forms among different regeneration stages. Using nonmetric, multiple scaling, we compared the composition of the soil seed bank among different regeneration stages and with standing vegetation composition. Furthermore, we outlined the influence of stand age, vegetation structure and soil properties on the density, richness and functional characterization of the soil seed bank using mixed effect models. The soil seed bank was dominated by herb seeds in all regeneration stages, and the density and richness of tree seeds increased with regeneration time and recovery of vegetation structure. Seed bank composition changed gradually with regeneration advance and differed from standing vegetation, containing a high amount of allochthonous seeds, especially in older stands. This observation highlights the importance of dispersal and habitat connectivity for the natural regeneration of these secondary forests. Shifts in soil seed bank composition towards slow-growing, animal-dispersed, non-pioneer species with larger, recalcitrant seeds in older regeneration stands indicate changes in vegetation composition along succession. Thus, our data indicate the importance of connectivity for forest regeneration and long fallow periods (> 40 years) to increase the performance of ecosystem services, resilience and stability of secondary forests arising during shifting cultivation practices.

Fruit traits of pioneer trees structure seed dispersal across distances on tropical deforested landscapes: Implications for restoration

Abstract Pioneer trees with fleshy fruits are typically planted in restoration projects to attract frugivores as a mean to increase dispersal and accelerate forest regeneration. However, differences in fruit traits of pioneer trees can potentially influence dispersal and their restoration outcomes. Here we investigated the effects of bird and plant traits, and distance to forest fragments, on the seed rain using a tree‐planting experiment replicated in 12 deforested sites in Brazil. Factors were fruit traits of pioneer trees (wind‐dispersed, bird‐dispersed with lipids or with carbohydrates and controls) and distance (10, 50, 300 m) from forest fragments. We found that density and richness of birds and seeds decreased exponentially with distance from fragments, yet these effects were minor compared to the effects of fruit traits on the structure of the seed rain. Overall, plots with fleshy fruited pioneers attracted much greater bird activity and seed dispersal than plots with wind‐dispersal pioneers and the controls. For instance, plots with carbohydrate‐rich fruits received more than twice the average species richness and density of birds and seeds of plots with lipid‐rich pioneer trees, surpassing wind‐dispersed pioneers by more than 80%, and controls by over 90%. Furthermore, the fruit trait treatments resulted in morphological shifts in the average traits of visiting birds. Significant differences in bill gape and flight capacities (wing‐loading) were associated with the differences in the seed rain associated with each treatment. Synthesis and applications. Understanding how trait‐matching processes mediating mutualistic seed dispersal by frugivores interact with distance‐dependent dispersal limitation on deforested tropical landscapes is critical for improving forest restoration efforts. This is especially relevant in the context of applied nucleation. As shown here, avian seed dispersal can thus be manipulated in restoration projects in order to increase connectivity and speed up forest recovery and the provision of the multiple ecosystem services that follow forest succession.

Extensive horse grazing improves grassland vegetation diversity, seed bank and forage quality of artificial embankments (Rhône River - southern France): Influence of extensive horse grazing on artificial embankments

Grazing by herds of herbivores modifies plant communities in different ways, depending on the herbivore species. Horse grazing is already known to be effective in increasing plant diversity and maintaining herbaceous vegetation, creating different types of patches and thus ensuring spatial heterogeneity. On an artificial embankment at the Donzère-Mondragon hydroelectric facility in the Rhône Valley, extensive grazing by a rustic horse (Konik-Polski) was introduced several years ago to control shrub encroachment and to enhance plant grassland diversity. Vegetation monitoring surveys over a five-year period (2014–2018) showed that horse grazing maintained patches of open and short grasslands and increased species-richness, in particular of annual species, some of which have heritage value. In contrast, overly-low grazing pressure led to the dominance of an unpalatable perennial grass (Brachypodium phoenicoides) at the expense of the annual species that significantly enhance the forage value of the most heavily grazed patches. Horse grazing also had a positive impact on the permanent seed bank of the soil, increasing its heterogeneity and the density of viable seeds. Extensive horse grazing thus appears to be a relevant management tool to preserve the diversity and the forage quality of the most open and short grasslands. Nevertheless, grazing pressure here remained too low to allow restoration of grasslands already colonised by woody species. Combining different livestock species might be a better alternative to pure horse grazing, to increase heterogeneity and diversity. Our results are discussed in relation to extensive horse grazing on artificial ecosystems, such as the embankments bordering rivers and canals.

Determination of Seed Density of Several Forest Trees Species to Improve the Successful Seed Germination

The success of tree seed germination for planting programme depends on several factors including tree seed density for seed sowing. The purpose of this study was to determine the seed density based on the level of seed aging to increase the success of seed germination of several forest tree species, namely white jabon (Anthocephalus cadamba (Roxb) Miq.), bambang lanang (Magnolia champaca Linn.), jelutung (Dyera polyphylla Miq.), kayu bawang (Azadirachta excelsa (Jack) Jacobs), and trema (Trema orientalis Linn. Blume).The seed density treatments covered 5 phases (d0, d1, d2, d3, d4) based on the germination percentage (GP). Seedlots variation was derived from 5 seed aging treatments (0, 48, 96, 144, and 192 hours).The determination of seed density was based on Kartika’s formula (1994).The results showed: (1) seed density of white jabon was 0.1g of seed/300cm2 with pure live seeds (PLS) of 1140 seedlings/ 0.1g of seed; (2) seed density of bambang lanang was 100 seeds/300 cm2 with GP of 58%; (3) seed density of jelutung seeds with 85% of GP was 50 seeds/600cm2; (4) seed density of kayu bawang with 83% of GP was 50 seeds/600 cm2 and (5) seed density of trema with 78% of GP was 100 seeds/600cm2. The longer the time of seed aging, the lower the value of germination percentage. Therefore,the lower the germination percentage, the seed density will be more tight.

Fragmentation reduces community-wide taxonomic and functional diversity of dispersed tree seeds in the Central Amazon.

The Amazon harbors one of the most diverse tree floras on earth, and most species depend on mutualists for pollination and seed dispersal. This makes them susceptible to reproductive decline in fragmented forest because many of these mutualists suffer area-related extinction in fragments. It remains unknown, however, whether this highly biodiverse tree flora will reproduce and ultimately persist in fragmented forest. We conducted a 2-yr study of seed fall in an experimentally fragmented, highly diverse Central Amazonian forest. We determined the effect of fragment size (1, 10, 100ha and continuous forest control) on the density, species richness, functional diversity and functional composition of seeds separated into two data sets: dispersed tree seeds, and undispersed tree seeds. Our results show a 3× reduction in the density of undispersed, non-pioneer tree seeds in fragments of all sizes, indicating reduced seed production of the non-pioneer tree community. The density of dispersed tree seeds was reduced by 6× in fragments of all sizes, while species richness was reduced by 6× in 1-ha fragments and by 3× in 10- and 100-ha fragments compared to intact forest. This provides evidence of reduced community-wide seed dispersal, which became more pronounced with declining fragment size. The functional diversity (FRic) of dispersed tree seeds was reduced 9.6× in small fragments, and significant shifts in the functional composition for 8 of the 10 reproductive and ecological traits studied were identified, suggesting compromised ecosystem functioning. These functional compositional shifts provide evidence for disrupted mutualistic processes in fragments, which include loss of pollination by bees, especially small eusocial (meliponid) bees, and loss of dispersal by primates and large birds, which reduced the frequency of large-seeded tree species. Fragments also lost rare and mature-forest species, and collectively these changes suggest that future tree communities in fragmented Amazonian landscapes will retain a taxonomically and functionally impoverished species pool with a biased functional composition unless efforts are undertaken to conserve dispersal by large frugivores and pollination by meliponid bees.

Genome-Wide Association Analysis Identifies Candidate Genes Regulating Seed Number Per Silique in Arabidopsis thaliana.

Seed weight and number ultimately determine seed yield. Arabidopsis seed number comprised of silique number and seed number per silique (SNS). Comparing seed development and weight, determinants of seed number remain largely uncharacterized. In this study, taking advantage of 107 available Arabidopsis accessions, genome-wide association analysis (GWAS) was employed to identify the candidate genes regulating SNS. GWAS-based genotype and phenotype association analysis identified 38 most significant SNPs marker sites that were mapped to specific chromosomal positions and allowed us to screen for dozens of candidate genes. One of them (PIN3) was selected for functional validation based on gene expression analysis. It is a positive regulator of Arabidopsis SNS. Although silique length of PIN3 loss of function mutant was not significantly changed, its SNS and seed density (SD) were significantly reduced as compared with the wild type. Notably, PIN3 overexpression lines driven by a placenta-specific promoter STK exhibited significantly shorter siliques, slightly reduced SNS, but significant increased SD compared with wild type, suggesting that PIN3 positively regulates SD through inducing ovule primordia initiation regardless of the placenta size. Ovule initiation determines the maximal possibility of SNS, and new genes and mechanism regulating SNS through modulating ovule initiation is worth further investigated.