Relationships among some seed traits, laboratory germination and field emergence in cowpea (Vigna unguiculata (L.) Walp.) genotypes

Abstract

A study was carried out to investigate the relationships among percentage water absorption during imbibition, leaching of electrolytes from seeds into steep water, germination and field emergence of 21 cowpea (Vigna unguiculata (L.) Walp.) genotypes differing in testa colour. Water absorption rate of cowpea seeds during imbibition and electrical conductivity (EC) of steep water were determined at 1, 2, 3, 4, 5, 6, 12, 18 and 24 hours. Significant differences were found between white and coloured cowpea seeds in terms of water absorption rate depending on imbibition time. Amount of water absorbed by seeds exceeded initial seed weight at 3 hours in white seeded and 18 hours in coloured seeded genotypes. EC of steep water showed similar trend to water uptake of seeds in both white and coloured seeded genotypes. Water uptake significantly influenced germination and field emergence in white seeded genotypes. The effect of water absorption rate on germination and field emergence at the end of the soaking period was not significant in coloured seeded genotypes. Negative and significant correlation was found between electrical conductivity and field emergence in white seeded genotypes but this relationship was not significant in coloured genotypes. The present study showed that EC is an important test to predict field emergence potential of white seeded cowpea genotypes under field conditions.