Evaluation of several methods for ascertaining seed quality of cowpeas for planting purposes

Alm Laboratory tests for warm germination, cool germination, electrical conductivity, and the seed oil, protein, and carbohydrate content were performed on twelve and nine seed lots of cowpeas [Vigna unguiculata ' (L.) Walp.] during 1980 and 1981, respectively. Results from the laboratory tests were compared with the emergence rate, dry matter production, and seed yield data obtained from these same seed lots when planted in the field on a Pullman clay loam soil (Torrertic Paleustoll) at two dates and two depths of planting.

Generally, no consistent correlations were observed between the seed biochemical components of oil, protein, and carbohydrate content and the emergence rate index, dry matter production, and seed yield of cowpeas. The only notable exceptions were a highly significant negative correlation between the seed oil content and the emergence rate index and the dry matter production during 1980.

The electrical conductivity was negatively correlated with the emergence rate index. However, these correlations were observed only at the early planting date during 1980 and the late planting date during 1981. In addition, the electrical conductivity was also negatively correlated with the dry matter production measured eight weeks after planting. An exception was found at the late planting date during 1980. No consistent relationship between electrical conductivity and seed yield was observed.

The warm germination and cool germination tests were correlated with the emergence rate index during 1980 and 1981 with the cool germination test values exhibiting the higher correlation coefficients. In addition, both the warm and cool germination tests were generally correlated with dry matter production eight weeks after planting. The major exception was with the late planted material during 1980. Again, no consistent correlations were observed between these lab tests and the final seed yield with the exception that a trend between the warm germination and yield was noted during 1981.

It appears from these studies that the warm germination and cool germination tests should provide useful information related to emergence rate and dry matter production of cowpeas. In addition, the electrical conductivity was generally negatively correlated with the dry matter production eight weeks after planting. The assaying for seed biochemical components provided no consistent information related to the emergence rate index or the dry matter production. None of the lab tests provided consistent information to predict the seed yields.