Field and laboratory experiments were conducted to evaluate the relationship between seed specific gravity, and/or seed density, to the phydiological quality, storability and seedling performance of cowpea seeds. Two methods of seed separation were used: a) separation using aqueous sucrose and b) using a table model fractionating aspirator. Seeds of different specific gravity separated by sucrose solution were compares using a standard germination test at 20-30oC and accelerated aging tests at temperatures of 40oC, 42oC, and 45oC for 48 and 72 hours. Germination responses indicated that low specific gravity seeds perform poorly when compared to high specific seeds and to the unseparated sample. However, seed vigor responses expressed by the accelerated tests results revealed significantly higher vigor for the unseparated sample than for any of the specific gravity classes, suggesting that the use of aqueous solutions for cowpea seed separation may have a detrimental effect on seed quality possibly due to water absorption during separation. Field emergence results in 1988 were not significantly different among specific gravity categories. In 1990, field emergence responses were similar to results obtained in the accelerated aging tests. The unseparated seeds were superior to the seeds which were separated using solutions. However, differences in yield in both 1988 and 1990 planting seasons were not related to seed specific gravity. The evaluation of the relationship between seed density expressed by 100 seed weight and storability of cowpea seeds was determined different density fractions obtained using a fractionating aspirator. Evaluations were conducted prior to storage and after 6, 9 and 12 months of open storage using the standard germination test, first count germination, accelerated aging test, and germination performance at low temperature. Vigor was also evaluated by comparing seedling elongation characteristics. No significant differents were observed in germination percentage for all categories prior to storage. However, tests conducted after each storage period revealed significantly higher germination for the high density seeds as well as for the unseparated control.

Field and laboratory experiments were conducted to evaluate the effects of seed specific gravity, and/or seed density, on physiological quality, storability and seedling performance of cowpea (Vigna unguiculata (L.) Walp) seeds. Seed preparation was accomplished by two methods: using aqueous sucrose solutions and by means of a table model fractionating aspirator.