Relationship between seed coat colour and seed vigour in cowpea (Vigna unguiculata Walp (L.)

In the present study, the 25 genotypes were grouped into two seed color groups including pigmented (n = 19; black, brown, dark brown, grey, dark grey seed color) and unpigmented (n = 6; cream and white seed color) for studying the association of seed coat color with seed vigor. Despite high germination (>84%) of all genotypes in the laboratory, unpigmented genotypes recorded low (34-54%) field emergence than pigmented genotypes (52-78%). Rapid initial (30 min) rate of water uptake (-0.75**), water uptake at one hour of imbibition (-0.70**), low proportion of seed coat (0.67**), and greater electrical conductivity of seed leachate (-0.72**) was associated with low field emergence in unpigmented cowpea genotypes. No significant correlation or association was observed between field emergence and laboratory germination in the present investigation suggesting that laboratory germination can not be used for predicting field emergence in cowpea. Instead, the electrical conductivity of seed leachate could be used to predict the field emergence of cowpea.