Large-sized Seeds Research Articles

Effect of fruit size on seed quality characeristics of pumpkin (Cucurbita moschata)

Seed size is one of the characters associated with seed quality. The influence of seed size on seedling vigour and crop performance has been established in different crops like soybean, maize, gram and ashgourd. Variability in fruit size and shape is seen in pumpkin, even under good management. A significant correlation was reported between the fruit weight and number of good seeds in cucumber. Large sized fruits selected at the field level ensured recovery of large size seeds, which produce healthy, vigorous seedlings that was reported in ashgourd. Such information is lacking in pumpkin. The present studies were undertaken to trace out the influence of fruit grading on seed quality in pumpkin cv. CO2

Caracterização da diversidade genética em feijão por meio de marcadores RAPD

Marcadores RAPD (Random Amplified Polymorphic DNA) foram usados para avaliar a diversidade genética entre 19 cultivares de feijão (Phaseolus vulgaris L.). Dos cento e oito locos de RAPD obtidos de 15 primers decâmeros, 70 foram polimórficos. Para estimar a distância genética foi usado o coeficiente de similaridade de Jaccard e as análises de agrupamento foram feitas pelos métodos UPGMA e Tocher. As análises de agrupamento confirmaram a ampla diversidade genética existente entre germoplasmas tropicais de feijão, separando as cultivares em dois grupos principais, correspondendo aos centros de domesticação Andino (genótipos de sementes médias e grandes) e Mesoamericano (genótipos de sementes pequenas). No grupo Andino, a diversidade genética relativa foi maior do que no Mesoamericano.

Horizontal and vertical distribution of desert seed banks: patterns, causes, and implications

This study examined small-scale seed distribution using published data collected using the same techniques and the same group of observers in four locations in North American deserts (Curlew Valley, Utah in the Great Basin Desert; Rock Valley, Nevada in the Mojave Desert; Silverbell, Arizona in the Sonoran Desert; and Jornada, New Mexico in the Chihuahuan Desert). The distribution patterns were examined horizontally (under shrub canopy to open areas) and vertically (measured at the soil surface and at four depth intervals) in relation to seed morphology. At all four sites, seed distribution of individual species was positively related to seed abundance. Horizontally, total number of seeds per unit area decreased from under the shrub canopy to intershrub areas. Vertically, total number of seeds declined as soil depth increased. Most species were only present in a small proportion of samples. Small seeds were either abundant and broadly distributed or rare and found in a few samples, but larger seeds were always low in abundance and restricted to a small proportion of samples. For annual species, significantly higher proportions of larger seeds than smaller seeds were found deeper in the soil. However, when much larger-seeded species, i.e. herbaceous perennials and shrubs, were included in the analyses, most very small or very large seeds were found in the upper-most layers of soils and intermediate to large-sized seeds deeper in the soils. Such seed distribution related to seed morphology and soil factors may have significant ecological implications in plant population dynamics and community structure in desert ecosystems.

Effects of kangaroo rat exclusion on vegetation structure and plant species diversity in the Chihuahuan Desert.

Long-term (1977-90) experimental exclusion of three species of kangaroo rats from study plots in the Chihuahuan Desert resulted in significant increases in abundance of a tall annual grass (Aristida adscensionis) and a perennial bunch grass (Eragrostis lehmanniana). This change in the vegetative cover affected use of these plots by several other rodent species and by foraging birds. The mechanism producing this change probably involves a combination of decreased soil disturbance and reduced predation on large-sized seeds when kangaroo rats are absent. Species diversity of summer annual dicots was greater on plots where kangaroo rats were present, as predicted by keystone predator models. However, it is not clear whether this was caused directly by activities of the kangaroo rats or indirectly as a consequence of the increase in grass cover. No experimental effect on species diversity of winter annual dicots was detected. Our study site was located in a natural transition between desert scrub and grassland, where abiotic conditions and the effects of organisms may be particularly influential in determining the structure and composition of vegetation. Under these conditions kangaroo rats have a dramatic effect on plant cover and species composition.

EFFECTS OF FERTILIZER AND SPACING ON SEED YIELD AND QUALITY IN SNAKEGOURD cv.PKM.1

An experiment was conducted to find out optimum fertilizer and spacing requirements for, the seed crop of snakegourd cv.PKM.1. The three fertilizer treatments were: 6:12:6, 9:15:9 and 12:24:12 g of the NPK/pit and three spacings were: 2 x 2.5m, 3 x 1m and 4 x 0.6m. The results revealed that application of 12:24:12g. of NPK/pit and sowing at a spacing of 2 x 2.5m were optimum for getting higher seed yield (119.87g/pl.). The treatments also recorded high recovery of large size seeds (61.5%), high, 100-seed weight (32.095g), germination (98%), root length (18.6 cm), shoot length (39.6 cm) and vigour index (5692).

A histological and elemental analysis study of the mature seed of Begonia semperflorens

The total element content and the subcellular distribution of mineral nutrients were investigated in a species that has very minute seeds. The major storage substances in the seed of Begonia semperflorens were lipids sequestered in lipid vesicles and proteins concentrated in protein bodies. Transmission electron microscopy revealed the presence of protein crystalloids and electron-dense globoid crystals in the protein bodies. These inclusions varied both in size and number in protein bodies from different tissues. Energy dispersive X-ray analysis of the globoid crystals showed the high Mg, K, and P levels characteristically found in phytin from large-sized seeds. Small traces of Ca were found in globoid crystals within protein bodies found in the provascular tissue of the embryo. Neutron activation analysis was used to measure the elemental composition of the whole seed and these results were correlated with the findings of energy dispersive X-ray analysis studies of globoid crystals. Key words: Begonia seed, energy dispersive X-ray analysis, protein body, globoid crystal, protein crystalloid, neutron activation analysis.

A Planting Template for Plug Flats

Seedlings are established in small growing containers to reduce cost of greenhouse space, while improving crop uniformity. These seedlings often are referred to as plugs. Vacuum seeders are used by larger growers to seed many flats per season (Bakos, 1983); however, individual growers, producing plants for their own use, may not be able to justify expensive seeding equipment. Several moderately priced vacuum seeders are available (Bartok, 1988). They consist of a metal tray with small drilled holes to hold the seed in place when a vacuum is applied to the tray from an external source. However, several problems with them exist. Seeds must be free of extraneous materials that might clog the small holes. A slight jarring of the plate, especially when the plate is turned upside down over the seed flat, may cause seeds to dislodge, resulting in unplanted cells in each flat. Also, different sizes of seeds and flats require completely different seeding plates and plate holders. A small grower may choose to seed flats by hand by placing seeds individually in each cell. This is feasible only for large-sized seeds or with pelleted seed. A simple, inexpensive, non-vacuum alternative design is presented and evaluated.

Germination Speed as a Predictor of Nursery Seedling Performance

Abstract Although they are not fully satisfactory, laboratory germination percentages are still better predictors of nursery-tree yield for both loblolly (Pinus taeda L.) and slash (Pinus elliottii Engelm.) pine seeds than any other means now available. Germination values, which combine both speed and completeness of germination, improve the predictability of nursery performance only in slowly germinating lots. Analyses of the reasons for better nursery growth of seedlings from stratified seeds reveal that under less favorable conditions they germinate faster than unstratified seeds. When equal-aged germinants from similarly-sized stratified and unstratified seeds are planted at the same time, seedling development is essentially the same. Seedlings from large-sized seeds (half-sib lots) did grow larger over a 10-week period than those from small-sized seeds.

EFFECT OF SEED SIZE ON PHYSICO-CHEMICAL CHARACTERISTICS OF SEEDS IN GROUNDNUT (ARACHIS HYPOGAEA L.) cv. POL 1 AND TMV 2

Investigations were carried out to understand the intor-relationship of seed sizo with physico-chemical characteristics in groundnut cv. POL1 and TMV 2. The large size seeds retained by 21/64" and 20/64" diameter round perforated sieves possessed significantly high 1000 seed weight and weight of primary axis, but the per cent weight of primary axis to weight of cotyledons was high in small size seeds retained by 18/64" and 16/64" diametor round perforated sieves. The EC value of leachate increased with increase in seed size. Though it is contradictory to the accepted vigour concept it may be attributed due to lack of membrane integrity in large seeds of groundnut due to invisible cracks developing during processing. The protein content and total free fatty acid content showed positive correlation with seed size. The oil content exhibited negative relationship in both the varieties.

Effect of Seed size and seed coat colour on Seed quality and productivity of red gram (Cajanus cajan L.)

of seeds viz., 625 6x8 retained and 6x8 possed occured in the seed lot. Besides sizes variation, seed coat colour varition also was encountered in one and the same sam- ple of seeds. Seeds possessing seed cost of uniformly tan colour uniformly dark tan colour and dark ten colour with black patches occurred Nearly 78 50 percent seeds could be recovered by processing with Extwire mesh sieve wich includea 56 6 per cent off coloured seeds About 10 04 per cent seeds out of 16.15 percent in 5x5 retained seeds possessed dark tan with black patches The vigour rating on the basis of stress test such as brick grit test, rare of weter absorption. electrical conductivity had clearly indicated the physiological stamina viz. high degreo of physialpgical activity possessed by large- sized and healthy seeds. All the vigour tests confirmed the superierity of large sized. dark tan as well as ten coloured seeds over small sized and off coloured seeds. Croup growth, seed production potential, reat growth and nodule formation were maximum for the large sized seeds Flowering advanced by 8.11 dass in plants from large-sized seeds when compared to those from the small-sized sends similarly the pod production. Off-coloured seeds viz, dark- ten with black patches ware found to carry 50 per cent of Rhizo.tonia solani infection white iniformly dark tan seocs carried 70 per cent Alternatie so and 30 par cant Ruizoctonia solani infection. Studies revealed that needs araded usina 6x6 wire mesh sieveor its eqcivalent round perforated sieve and free from off-coloured sands should be used for maximising seed production.

Effects of Nitrogen, Phosphorus, and Plant Density on Sunflower1

AbstractIt is generally recognized that appropriate plant density and appropriate fertilizer application to deficient soil are necessary for optimum yield of crops. These variables also affect the quality of some crops. There is limited research data on the effects of these variables on yield and quality factors of oil and confectionery cultivars of sunflower (Helianthus annuus L.) grown in North Dakota. The objectives of this research were to determine the effects of three rates of nitrogen fertilizer, two rates of phosphorus fertilizer, and three plant densities upon seed yield, head size, oil concentration of oil cultivars, and seed size of confectionery cultivars.Nitrogen fertilizer increased seed yield, head size, oil yield from oil‐type cultivars, and percentage of large size seeds from confectionery cultivars. However, N reduced oil concentration of oil‐type seeds and percentage of medium size seeds of confectionery cultivars. Yield response to nitrogen was obtained at all locations because soil tests for nitrate‐N to a 61 cm soil depth were less than 60 kg/ha at planting time.Phosporus fertilizer failed to increase seed yields in 10 of 12 trials and had little effect on size of confectionery seeds and oil concentration of oil‐type seeds. Lack of response to phosphorus cannot be explained by soil test data.Increasing plant density increased seed yield, yield of oil from oil‐type sunflower, and percentage of medium‐size seeds from confectionery cultivars. Increasing plant density reduced head size and percentage of large‐size seeds of confectionery cultivars. Percentage of small sized confectionery seeds was increased by increasing plant density and decreased by increasing rate of nitrogen fertilizer.Results of this study show that nitrogen and plant density have a relatively large effect on seed yield and a smaller effect on oil concentration and seed size.

Ontogenetic Study of Urease in Jack Beans, Canavalia ensiformis (L.) DC.

Urease occurs in all parts of the jack bean (Canavalia ensiformis [L.] DC.) plant. The floral parts contain 1/6-1/10 as much urease as the vegetative shoot apices and green leaves. The embryo and the seedling, excluding cotyledons containing about 1% of the total units, showed a constant amount of urease up to 10 days following the initiation of germination. Shoot apices contained 1-2 units of urease per 25 apices for a period of about 7 weeks and possibly thereafter. Studies on cotyledons of germinating seedlings showed the existence of three phases in urease activity. For the first few days, the urease content remained constant, and the specific activity increased somewhat; the second phase was characterized by a declining urease content but increasing specific activity; and in the last phase both the amount of urease and its specific activity declined. Dark-grown seedlings showed the same pattern except that the first phase was somewhat prolonged. The peak of proteolytic activity of the cotyledonary extracts was observed in the first phase around 6-7 days after germination began. Possibly, changes in the specific activity of urease may be a reflection of the prevailing proteolytic activity. Studies on cotyledons of maturing seeds showed that the increase in urease units per gram of dry wt increased with increasing dry wt of the cotyledons, and the rate of synthesis was very high in the 6-7 week post-fertilization period. A difference of 7-10 days in the age of the seeds from pods harvested in this period was reflected in the urease content. In the last few weeks of maturation of seeds, however, the rate of urease synthesis was slow, and at this stage the differences in age did not show up in the urease measurements. Small-sized fully mature seeds may possess double the specific activity of the large-sized seeds on a per-gramprotein basis. Probably, in the later part of seed maturation proteins other than urease are synthesized in greater amounts in the seeds attaining a large size than in the small ones.

Studies on the Hard Seed of Milk Vetch (Astragalus cinicus L.) : IV. Seed quality and hard seed content of milk vetch in relation to harvesting time

The authors investigated on the quality of seed, germination and hard seed content of milk vetch seed in relation to harvesting time for every five days in the field. 1) The germination percentage of seeds was higher in late harvested seeds than that of early harvested seeds, and also the germination tended to be quicken in late harvested seeds (Fig. 2). 2) Hard seed content in the first harvesting time (I) was 7.9 per cent and it was the lowest. At the harvesting time II, it was 17.2 per cent. At the harvesting time III, it was 18.8 per cent and was the highest. And this time contained about 30 per cent of immatured green pods and about 55 per cent of matured black pods. And at harvesting time IV and V, the hard seed content was 11.9 and 12.0 per cent respectively, and it was lower at these times than those of the immatured stages such as harvesting time II and III (Fig. 3). 3) The percentage of corrupt seeds was higher at early harvesting time. The hard seed content for viable seeds, therefore, came to show the highest at harvesting time II (Fig. 4). And this time contained about 9 per cent of matured black pods and about 63 per cent of immatured green pods (Table 1). 4) The weight of 1000 seeds increased as harvested later, but the increase was not so large in seeds harvested after harvesting time III. And the proportion of large-sized seeds was large in late harvested seeds (Table 2). Although the germination percentage was remarkably low in the seeds of less than 14-meshes, no difference of germination percentage was found in the seeds of 14-meshes or larger seeds. 5) From the experimental results mentioned above, it was generally considered that the seeds harvested and dried at immatured stage have the tendency to hardiness than that of harvested after normal maturation on the stalk.