Cottonseed Density: Associated Germination and Seedling Emergence Properties

Recent studies have indicated that separation of cottonseed (Gossypium hirsutum L.) for improvement in seed quality should be based on seed density rather than seed size or weight. Seed density is closely related to embryo maturity and is more independent of genotype than are other seed properties. The primary objective of this study was to determine the effect of seed density on some of the processes associated with cottonseed germination and seedling establishment of several cultivars. Acid delinted seed were separated into four density groups using a pneumatic separator. Rate of imbibition, quantity and quality of material leached from the seed, rate of radicle elongation, germination and seedling emergence percentages were measured as indicators of seed quality and seedling vigor potential. Germination percentages were directly related to both seed density and seed weight, with the better correlation existing with seed density. The rates of imbibition and radicle elongation were related to seed density within a cultivar with differences existing between cultivars. A slower rate of radicle elongation was observed for the highest density class during the first 2 to 3 days of germination, which was related to a decreased rate of imbibition during the first 8 hours of contact with water. The quantity of soluble sugars, Ca, and K leached from the seed during imbibition was inversely related to seed density, suggesting interferences existed during seed development or deterioration had occurred in the low density seed. Seed density was highly related to rate of emergence, total emergence, and seedling survival under both growth chamber and field conditions. The results obtained suggest that seed density is the best predictor of cottonseed germination, emergence and potential seedling vigor. Seed separation for improvement in seed quality should be based on density rather than other seed properties.