Effect Of Seed Size Research Articles

Effects of Seed Size and Frequency on Seed Dispersal and Predation by Small Mammals.

Frequency-dependent predation is common in predator-prey interactions. Size is an important characteristic of seeds and is crucial in the regeneration stage of plant seeds. However, the frequency dependence of animal predation on seed size has not been reported. In this study, we conducted a field experiment and used different sizes of Liaodong oak (Quercus wutaishanica) seeds to test the frequency dependence of intraspecific seed size selection in rodents. We used the number ratio of large to small seeds as the frequency. The results show that the rate of small seeds being eaten in situ was significantly higher than that of large seeds (p < 0.05). The rates of different-sized seeds being eaten after removal decreased with increasing frequencies, and there was no significant difference between frequencies except for 1:9 and 9:1. The rates of large seeds being scatter-hoarded were significantly higher than those of small seeds at different frequencies (p < 0.05). The eating distances after removal of large seeds were significantly longer than those of small seeds at the same frequencies (p < 0.05). Furthermore, the scatter-hoarding distances of large seeds were significantly longer than those of small seeds at three frequencies (1:9, 3:7, and 9:1) (p < 0.05). That is, rodents consumed more small seeds in situ, dispersed and scatter-hoarded more large seeds, and dispersed large seeds over longer distances. Rodents exhibited a negative frequency dependence for small seeds and a positive frequency dependence for large seeds on being eaten in situ. Moreover, rodents exhibited a negative frequency dependence for large seeds and a positive frequency dependence for small seeds on being eaten after removal and scatter-hoarding. These results reveal the frequency dependence of rodent selection on seed size and provide new insights into animal-mediated seed dispersal and the regeneration of plant populations.

Effect of Seed Size on Growth, Yield and Seed Quality of Jack Bean (Canavalia ensiformis (L.))

This research aimed to investigate the effect of seed size on growth, yield and seed quality of Jack beans cultivated in field conditions. The experiment was conducted at Faculty of Natural Resources and Agro-Industry, Kasetsart University Chalermphrakiat Sakonnakhon Province Campus. The experimental design was Randomized Complete Block Design (RCBD) with 3 replications and 3 treatments, and consisted of 3 different seed sizes of Jack bean (small, medium and large). The results indicated that seed size had no significant effect on growth (plant height, leaf number and weight of canopy). However, statistically significant differences (P&lt;0.05) were found in fresh and dry biomass yields, whereas large seed size had the highest biomass yield without significant difference from seed yield. The 3 sizes of jack bean gave an average seed yield of 402.07 kg/rai. In term of seed quality, it was found that all 3 sizes of jack beans seed had no significant effect on physical quality and physiological quality in both standard germinations, germination index and a number of days used for germination. However, seed sizes had a significant effect on seedling biomass weight. The large seed had the highest weight (0.62 g/plant). Therefore, this study concluded that the three seed sizes (small, medium, and large) did not affect the growth, yield and seed quality of jack beans although the large size seed had the highest biomass yield.

Effects of Seed Size and Cache Density on the Seed Fate of Quercus wutaishanica Mediated by Rodents.

Animal-mediated seed dispersal is very important for plant population regeneration and the stability of forest ecosystems. Seed size and cache density are important factors for seed dispersal, but we still know little about seed size selection at different cache densities. Here, we conducted field experiments in a Larix principis-rupprechtii plantation in the Liupan Mountains in Ningxia province to investigate the effects of tag-marked Quercus wutaishanica seeds of different sizes and cache densities on predation and the scatter-hoarding behavior of rodents. The results showed lower proportions of intact in situ (IIS) and eaten in situ (EIS) large seeds than small seeds at all levels of cache density, with the exception of IIS seeds at a 6.25 seed·m-2 cache density. A higher proportion of small seeds were eaten after removal (EAR), but a higher proportion of large seeds were scatter-hoarded (SH) by rodents at most cache densities. Furthermore, rodents preferentially removed large seeds farther away for eating or scatter-hoarding. The IIS and EIS proportions of both large and small seeds declined, but the proportion of the two types of seeds that were EAR fluctuated, increasing with increasing cache density. Rodents preferred to increase the proportion of scatter-hoarding of large seeds with increasing cache density, whereas the proportion of scatter-hoarding of small seeds was maximized at a cache density of 6.25 seed·m-2. Both the eaten distance after removal (EDAR) and scatter-hoarded distance (SHD) increased with increasing cache density. These results suggest that large seeds are more likely to be scatter-hoarded and removed to longer distances than small ones. Rodents tended to reduce the seed proportion of EIS seeds and increased the proportion of seeds EAR and SH, and accordingly increased EDAR and SHD with increasing cache density. This study provides some scientific basis for animal-mediated seed dispersal.

Aegle marmelos- Effect of Seed size and pre-sowing treatment on seed germination

Aegle marmelos (L) corr. is a medicinal tree, mentioned in Charka Samhita and mentioned as necessary item in Ayurvedic medicine. Its fruits and leaves are used to treat dysentery, dyspepsia, neurological disease, edema, vomiting, and rheumatism. Seeds of Bael were collected from three locations in Rajasthan. These seeds were after proper cleaning and storage was tested for germination vigour and other parameters using different treatments and growth regulators in different concentrations. It was found that about 50 percent of germination occurs in freshly harvested seeds without any growth regulators and with GA3 it increases to 75 percent. Various other parameters viz. mean germination time and average germination percentage etc of all three seedlots were tested and presented in this paper.

Effect of Seed size and pre-sowing treatment on seed germination of Terminalia bellirica

Terminalia bellirica Roxb is a large tree up to 40 meters high belongs to family Combretaceae. Due to over-exploitation (because of its multipurpose uses), tremendous population pressure, rural poverty, absence of appropriate government policy, accelerated growth of synthetic drugs and inappropriate utilization of forest products, these vital plat resources are being declined besides these, natural regeneration through seeds is very poor, uncertain and required long time to germinate, thus the State Forest Departments avoid the species in the afforestation and/or reforestation programs. Seeds from different locations in Rajasthan were analyzed for seed quality as well as germination potentials with different treatments. GA3 was found to increase seed germination in comparison to others. A detailed work with review work on its reproductive biology is presented in the present study.

Effect of Temperature, Seed Size, Sowing Depth, and Position on Seed Germination and Seedling Growth of Bauhinia retusa Roxb. and Bauhinia variegata L.

In urban forestry plantations are implemented in different cities of the world for social and environmental benefits. Bauhinia retusa and Bauhinia variegata are important species and to be used as large-scale plantation programs in urban forestry which might solve or mitigate urban, social, and environmental issues such as improving the physical &amp; mental health of residents, food and nutrition security, increasing urban biodiversity, cooling the neighboring, preventing soil erosion, flooding, and mitigating greenhouse gas emissions and air pollution. The present study was conducted with the aim of producing quality planting material for B. retusa and B. variegata in the nursery for afforestation programs. Seeds of B. retusa and B. variegata were collected from the natural habitats to assess seed germination and seedling growth. Seeds were stored in different types of containers at room temperature and later on exposed to 15, 20, and 25 °C in seed germinator. Seeds were further sown in polythene bags according to the seed size, seed coat color, seed sowing depth, the orientation of seeds, and the result of the emergence of seedlings, their growth, and biomass were estimated. A two-way analysis of variance was calculated to estimate the variation among the studied parameters. Results revealed that a constant 25 °C temperature was considered best for seed germination of both the Bauhinia species. Polybags were found the most suitable for storing the Bauhinia seeds among the storage containers. The seedling emergence and growth were maximum in yellow color and large seeds. In B. retusa, seedling emergence, and growths were the maximum in seeds sown at a horizontal position and in B. variegata at an upright position. Seedling emergence, length, and biomass were recorded the maximum when seeds of B. retusa were sown at 4 cm depth and B. variegata seeds were sown at 2 cm depth. The study recommends that the yellow color seed that has to be sown at 2 cm to 4 cm depth with upright and horizontal positions is considered best for the production of quality planting stock of both studied Bauhinia species.

Effect of Seed Size and Source Variation on Germination Potentials of Anacardium occidentale (Linnaeus) Seeds

Size is one of seed quality that determines the rate of seed germination while seed source presents the best genetic materials carried by the mother tree and transferable to the offspring. This study investigated the effects of seed size and seed source on germination percentage of Anacardium occidentale. 81 viable seeds of different seed sizes (large, medium, and small) collected from mother trees at three different sources (Funaab, Camp and Obantoko) in Abeokuta, Ogun State were sown in polythene pots. Seeds of the same size were sown at the rate of 3 seeds per pot with 3 replicates for each of the sizes sown. The experiment was laid out in 3 x 3 factorial in Completely Randomized Design (CRD). Daily record of new sprouts was taken, and the germination percentage was calculated, collected data was analyzed using Analysis of Variance (ANOVA) in SAS. Germination percentage (98%) was significantly (P&lt;0.05) higher in Small sized seeds which was not different from medium sizes seed (92.67%) while seeds sourced from Camp had the highest germination (98%) at (P&lt;0.05). Highly significant interactions (p&lt;0.05) were recorded between seed size and seed source. The smaller the size of Anarcadium occendalis seeds the higher the germination within different sources of collection.

Effects of Nutrient Supply and Seed Size on Germination Parameters and Yield in the Next Crop Year of Winter Wheat (Triticum aestivum L.)

Winter wheat is one of the most important crops globally and also in Hungary. Hungary has excellent crop production potential including seed production. The aim of our experiment is to determine the effects of different amounts and proportions of nutrients and those of the seed size of winter wheat in laboratory seed tests on the seed parameters (germination percentage, germination power, seedling health and vigour), as well as in field tests of the seed parameters (emergence percentage and yield of next crop year). Laboratory seed tests of winter wheat variety GK Petur were conducted with seeds that underwent ten nutrient treatments and of three seed size fractions over four crop years, together with field experiments in three growing seasons. Compared to the untreated control group, N treatments significantly decreased the health of the seedlings in the next generation of winter wheat. PK treatments without N increased the germination percentage, vigour value and emergence percentage significantly, but the health of the seedlings decreased. In contrast, NPK treatments with a ratio of 2:1:1 improved all the tested parameters compared to those of the control group. The increase in seed sizes significantly increased the germination power, seedling health, vigour value, emergence percentage and the yield of the next crop year. It can be concluded that the factors of nutrient supply, crop year of the seed production and the seed size significantly influence the quality of the seed (germination percentage, germination power, seedling health, vigour and emergence percentage), thus also the yield of the next generation.

Seed size effects on plant establishment under low atmospheric CO2, with implications for seed size evolution.

Low atmospheric CO2 concentration depresses photosynthesis and resource use efficiency, and therefore can inhibit phases of the life cycle such as seedling establishment. Seed reserves can compensate for photosynthetic inhibition by accelerating seedling growth. We therefore hypothesize that seedlings arising from large seeds show less inhibition from low atmospheric CO2 than young plants from small seeds. Seed size effects on seedling responses to low CO2 may also be enhanced in warm environments, due to greater photorespiration at high temperature. Phaseolus and Vigna seeds differing in mass by over two orders of magnitude were planted and grown for 14 d in growth chambers with CO2 concentrations of 370, 180 or 100 ppm, in thermal regimes of 25 °C/19 °C, 30 °C/24 °C or 35 °C/29 °C (day/night). We measured leaf area expansion, shoot growth and mortality of the seedlings arising from the variously sized seeds at 14 days after planting (14 DAP). Relative to small-seeded plants, large-seeded genotypes produced greater leaf area and shoot mass at 14 DAP across the range of CO2 treatments in the 25 °C/19 °C and 30 °C/24 °C regimes, and at 100 ppm in the 35 °C/29 °C treatment. The proportional decline in leaf area and seed mass with CO2 reduction was generally greater for seedlings arising from small than from large seeds. Reductions in leaf area due to CO2 reduction increased in the warmer temperature treatments. In the 35 °C/19 °C treatment at 100 ppm CO2, seedling mortality was greater in small- than in large-seeded genotypes, and the small-seeded genotypes were unable to exit the seedling stage by the end of the experiment. The results support a hypothesis that seedlings from large seeds grow and establish better than seedlings from small seeds in warm, low CO2 environments. During low CO2 episodes in Earth's history, such as the past 30 million years, large seeds may have been favoured by natural selection in warm environments. With the recent rise in atmospheric CO2 due to human activities, trade-offs between seed size and number may already be affected, such that seed size today may be non-optimal in their natural habitats.

Effects of Forest Gap and Seed Size on Germination and Early Seedling Growth in Quercus acutissima Plantation in Mount Tai, China

Elucidating the influence mechanisms of seed germination and seedling growth is important for revealing the natural regeneration of forest plantations. We collected the seeds from 58-year-old Quercus acutissima Carruth. forest, and the seeds were further divided into three classes: large, medium, and small, and sown under the forest gaps (I, 197.82 m2; II, 91.85 m2, III, understory) to observe seed germination and early seedling growth. Precipitation in the study area and soil moisture content in the forest gaps were also observed during the trial period. The results showed that the precipitation in 2019 was similar to that in 2020; both were significantly lower than the precipitation in 2021. The difference in soil water content between gaps I and II was not significant, and both were significantly lower than III. The order of seedling emergence rate in gaps was II &gt; III &gt; I, but the minimum was almost close to zero in I. Large and medium seeds showed significantly greater emergence rate than small seeds. The seedlings of II had higher seedling height, ground diameter, ground diameter relative growth rate, seedling biomass, root surface area, and root volume than those of III. Large seeds had the highest ground diameter, ground diameter relative growth rate, biomass, root mass ratio, root shoot ratio, and root surface area. Correlation analysis showed that seedling biomass was significantly and positively correlated with root surface area and root volume, and significantly and negatively correlated with specific root length and specific root surface area. The regulation of soil moisture in the gap and the adaptability related to seed size were two key factors influencing the seed germination and early seedling growth of Q. acutissima.

Genome-Wide Analysis of the GW2-Like Genes in Gossypium and Functional Characterization of the Seed Size Effect of GhGW2-2D.

Cotton is one of the most economically important crops worldwide. Seed size is a vital trait for plants connected with yield and germination. GW2 encodes a RING_Ubox E3 ubiquitin ligase that controls seed development by affecting cell growth. Here, are few reports on GW2-like genes in cotton, and the function of GW2 in cotton is poorly understood. In the present study, a genome-wide analysis identified 6 and 3 GW2-like genes in each of the two cultivated tetraploids (Gossypium hirsutum and G. barbadense) and each of their diploid ancestral species (G. arboreum, G. raimondii), respectively. GhGW2-2D has the same functional domain and high sequence similarity with AtDA2 in Arabidopsis. Overexpression of GhGW2-2D in Arabidopsis significantly reduced seed and seedling size, suggesting GhGW2-2D is a potential target for regulating cotton seed size. These results provided information on the genetic and molecular basis of GW2-like genes in cotton, thus establishing a foundation for functional studies of cotton seeds.

Effects of Hydro-priming and Seed Size on the Germination, Root, and Shoot of Peanut (Arachis hypogaea L. var. NSIC Pn18) Grown under Drought Conditions

This study aimed to assess the effects of hydro-priming duration and peanut seed size on the germination performance and the root and shoot characteristics of peanut seedlings under drought conditions. Two experiments were conducted under the laboratory and nursery. Peanut seed sizes (S1: small seeds and S2: large seeds) designated as the main plots, and duration of priming (P1: 0 hour, P2: 5 hours, and P3: 10 hours) was considered as the subplots. A 2 × 3 split-plot completely randomized design with three replications was used. Ten small and ten large seeds were placed in 4 × 4 inch plastic containers for laboratory experiment and 25 × 25 cm cellophane for pot experiment per treatment filled with dry soil at 10% moisture content. Large seeds soaked at 5–10 hours emerged earlier than the unsoaked seeds in this study. Final germination enhanced in bigger seeds also resulted in an increase in the germination index (seeds day−1) and the seedling vigor index. Likewise, larger seeds produced shorter shoots and plant height but broader shoots with more leaves. It is recommended that bigger seeds can be a good source of planting materials when planted in drought conditions and primed at 5–10 hours. However, unprimed smaller seeds can be used as planting materials in moist soil conditions. The interaction effect was noted on the fresh shoot weight of peanut plants as affected by seed size and hydro-priming. Higher fresh shoot weight of peanut plants when exposed to priming regardless of the seed size was obtained.

The Effect of Seed Size on Seed Recovery and Quality in Chickpea (Cicer arietinum L.)

Background: Quality seed is major input in increasing the productivity of agricultural crops. Seed after harvesting contains many undesirable materials and unfit for sowing. If the farmer is to be persuaded to pay for high quality seed, the seed he buys must be undeniably be pure and flow without difficulty through planter or drill. To separate different size seed material, many equipments have been developed which exploit the differences between the physical characteristics of seeds. Methods: An experiment was conducted to standardize the sieve size for seed grading in chickpea. The freshly harvested seeds of were graded using different sieve sizes. The screens used in this experiment were 7.0 mm R, 6.50 mm R, 6.0 mm R, 5.50 mm R, 4.75 mm R, 3.75 mm R and Bulk seeds (control). The seeds which retained over the screen were subjected to seed recovery and quality tests. Result: The results of the experiment indicated that the seed recovery ranged from 90.4 per cent to 97.82 per cent among the different size grades. As the screen size decreased from 7.0 to 4.75 mm, the per cent seed recovery was increased but seed quality parameters were decreased and well below the Indian Minimum Seed Certification Standard (IMSCS). The positive association of seed size and seed qualities were recorded. The 5.5 mm sieve recorded 96.4% seed recovery as compared to 6.0 mm sieve (94.4%) and found to be better by considering two per cent higher seed recovery and other higher germination, vigour index although there is recommendation is 4.75 to 6.0 mm range. Hence, the seed producer is benefitted by higher seed recovery and profit and without compromising minimum seed certification standards.

Seed size affects rodent-seed interaction consistently across plant species but not within species: evidence from a seed tracking experiment of 41 tree species.

Scatter-hoarding rodents play a crucial role in seed survival and seed dispersal. As one of the most important seed traits, seed size and its effect on rodent-seed interaction attract lots of attention. Current studies usually target one or a few species and show inconsistent patterns; however, few experiments include a large number of species although many plant species usually coexist in natural forest and overlap in fruiting time. Here, we tracked the dispersal and predation of 26100 seeds belonging to 41 tree species in a subtropical forest for 2 years. Most species showed no relationships between seed size and rodent foraging preference, while the remaining species displayed diverse of patterns: monotonic decrease and increase trends, and hump-shaped and U-shaped patterns, indicating that a one-off study with a few species might give misleading information. However, the seed size effect across species was consistent in both years, indicating that including a large number of species that hold a sufficient range of seed size may avoid the aforementioned bias. Interestingly, seed size effect differed among rodent foraging processes: a negative effect on seed harvest, a hump-shaped effect on seed removal and removal distance, while a positive effect on overwinter survival of cached seeds, indicating that rodents may make trade-offs between large and small seeds both among foraging processes and within a single process, thus lead to a parabolic relationship between seed size and seed dispersal success, that is medium-sized seeds were more likely to be removed and cached, and transported with a further distance.

Effect of Seed Size and Different Pretreatment Methods on Germination of Albizia zygia (DC.) J. F. Macbr

Albizia zygia produces valuable timber which has received some level of prominence in the international market. However, the seeds are dormant, and the tree species remain undomesticated. This study was conducted to evaluate the effect of seed size and presowing on the germination of Albizia zygia in a nursery. Seeds were grouped into four categories in regard to their length, small (≤0.5 cm), medium (&gt; 0.5 &lt; 0.8 cm), large (≥0.8 cm), and mixture of small, medium, and large seeds. The seeds were subjected to five main seed pretreatment methods, namely, soaking in sulphuric acid (H2SO4) for 2 minutes, mechanical scarification, soaking in hot water for 5 minutes, soaking in cold water for 24 hours, and control where seeds were sown without any treatment. The results indicate that combination of mechanical scarification and large seeds produced the highest (100%) germination. Hot water treatment was effective in large seeds producing 69.0% germination. The increased germination for mechanically scarified seeds suggests that seed dormancy in Albizia zygia is mainly due to its hard seed coat. Therefore, it is recommended to farmers to adopt use of mechanical scarification and large seeds, since it is safe and effective.

Effect of Seed Size and Salinity on Germination and Vegetative Growth of Wheat (Triticum aestivum L.) Variety Imam

To investigate the effect of seed size and salinity stress on the germination and vegetative growth of wheat variety Imam, a laboratory and a pot experiment were conducted during the winter season of 2016. The experiments were conducted at the Seed Laboratory of Agronomy Department and at the Nursery, Faculty of Agriculture, University of Khartoum, (Shambat). Seed size treatments were selected on the basis of seed diameter, and were categorized into three classes of small; medium and large.Salinity concentrations were: EC0 (control); EC2 (0.24 mM NaCl L-l); EC4 (0.28 mM NaCl L-l); EC6 (0.39 mM NaCl L-l); EC8 (0.41 mM NaCl L-l) and EC10 (0.59 mM NaCl L-l). The experiments were conducted using a completely randomized design with two replicates for the germination test and three replicates for the pot experiment. Data were collected on:germination percentage on the 4th and 8th day after planting; plant height; number of leaves per plant; leaf area; number of tillers per plant and dry matter yield. The data were statistically analyzed using ANOVA and mean separation using LSD. The results revealed that seed size class did not show significant (p ≤ 0.05) effect on germination percent of wheat. However, salinity significantly (p ≤0.05) affected germination at both readings. Small seed class registered higher germination at EC4 and EC10. For the pot experiment, the results revealed that seed size class did not have a significant (p ≤ 0.05) effect on the studied parameters. However, better performance was observed for the large seed size class as compared to the other seed size classes. Salinity had a significant (p ≤ 0.05) adverse effect on all measured growth parameters and reduced dry matter yield by 10.4 %, 11.7 %, 47.7% , 38.5 % and 72.2 % at EC2 and EC4, EC6, EC8 and EC10, respectively, as compared to EC0. Except for leaf number, most of the interactions between seed size and salinity were significant (p ≤ 0.05). Further research is neededto confirm the reported effect of salinity on growth and yield of wheat variety Imam.

The Effect of Seed Size on Germination and Seedling Growth in Sweet Chestnut (Castanea sativa Mill.)

The quantity and quality of seedlings in the nursery has an impact on the success of re-establishment and later growth. High germination rates enable a sufficient number of seedlings, and their quality is assessed using a number of parameters, including seedling height and root collar diameter. These parameters are influenced in some species by seed size, but the correlation between them is species-specific. The model species in this research was sweet chestnut (Castaneasativa Mill.), and seeds from 12 populations from two distinct biogeographical regions of Croatia were collected. We examined the influence of seed size on four parameters: germination rate, seedling height, root collar diameter and sturdiness quotient. Seed size has been shown to have a positive influence on both seedling height and root collar diameter, whereas no such correlation was noted for germination rate and sturdiness quotient. Significant differences in nut size and seedling growth parameters were found between the Mediterranean and continental populations, with higher values observed in the coastal Mediterranean populations. We concluded that seed origin and seed size have a significant impact on seedling growth and are important factors to consider when choosing seed material. Further nursery operations should consider seed origin and local environmental conditions when choosing seedlings for reforestation efforts and general forest operations.

Heterogeneous Nucleation of Butanol on NaCl: A Computational Study of Temperature, Humidity, Seed Charge, and Seed Size Effects.

Using a combination of quantum chemistry and cluster size distribution dynamics, we study the heterogeneous nucleation of n-butanol and water onto sodium chloride (NaCl)10 seeds at different butanol saturation ratios and relative humidities. We also investigate how the heterogeneous nucleation of butanol is affected by the seed size through comparing (NaCl)5, (NaCl)10, and (NaCl)25 seeds and by seed electrical charge through comparing (Na10Cl9)+, (NaCl)10, and (Na9Cl10)− seeds. Butanol is a common working fluid for condensation particle counters used in atmospheric aerosol studies, and NaCl seeds are frequently used for calibration purposes and as model systems, for example, sea spray aerosol. In general, our simulations reproduce the experimentally observed trends for the NaCl–BuOH–H2O system, such as the increase of nucleation rate with relative humidity and with temperature (at constant supersaturation of butanol). Our results also provide molecular-level insights into the vapor–seed interactions driving the first steps of the heterogeneous nucleation process. The main purpose of this work is to show that theoretical studies can provide molecular understanding of initial steps of heterogeneous nucleation and that it is possible to find cost-effective yet accurate-enough combinations of methods for configurational sampling and energy evaluation to successfully model heterogeneous nucleation of multicomponent systems. In the future, we anticipate that such simulations can also be extended to chemically more complex seeds.

Effects of Seed Size on the Germination and Early Growth of African Baobab (Adansonia digitata L.)

The effects of seed size on the germination and early growth of A. digitata were assessed. Seeds were sourced locally within the University of Ilorin Campus. One hundred viable seeds were selected from each of the size classes. The seed weight, length, breadth, and width were measured for all the selected seeds. Mean weight, length, breadth, and thickness were: 0.62 g, 9.16 mm, 7.45 mm, and 5.85 mm, respectively for small seeds. 0.41 g, 9.54 mm, 7.68 mm, and 6.03 mm, respectively for medium seeds; and 0.44 g, 9.92 mm, 7.89 mm, and 6.21 mm, respectively for large seeds. The experiment was laid out in a completely randomized design (CRD). Seed dormancy was broken through the acid scarification method by soaking in H2SO4 at 70% concentration for 20 minutes with constant stirring. Variables of interest include: leaves number, seedlings height, collar diameter and leaf area. Based on the results of this finding, medium and large seeds germinated in 7 days after sowing while small seeds germinated in 10 days after sowing. Large seeds had the highest germination percentage (55%), followed by medium seeds with 27%. The small seeds were the least in terms of germination rate (21%). There was no significant difference in mean seedling heights, collar diameters and number of leaves among the seed size classes (P˃0.05). Mean leaf area significantly differed among the three size classes (P˂0.05). The result showed that large seeds gave best germination at a shorter period than the medium and small seed sizes. Thus, large seeds of A. digitata are recommended in propagation activities involving the species.

Studies on effects of seed size on germination and seedling growth of Elaeocarpus and Canarium tree species

An investigation was undertaken on two medicinally important evergreen tree species of Western Ghats namely, Elaeocarpus munronii and Canarium striuctum to improve seed germination and enhance seedling growth in nursery. The seeds collected from two randomly chosen trees in each species were used for the study. In general seed germination was very poor in both the species. The maximum germination of 4.66 per cent was observed in Elaeocarpus munronii and it was 13.33 per cent in Canarium striuctum. Though big and medium size seeds recorded higher germination per cent than small size seeds in both the species studied, the seed size effect on germination was found to be non-significant. The results of the study revealed that seed size did influence seedling growth in both the species. Seeds of bigger size produced seedlings with higher values of shoot length, root length and collar diameter but their effect on dry matter accumulation was not significant. The effect of seed treatments on seedling growth was not noticed in Elaeocarpus munronii while seed treatment with sulphuric acid in Canarium striuctum showed slight but significant increase in shoot length, however, other growth parameters remained unaffected. The effects of seed size as well as of seed treatment on germination and seedling growth was found to be similar in both the trees species studied.