Gene Action Controlling Seed Size in Cowpea (Vigna Unguiculata L. Walp)
Cowpea with large seed sizes is one of Ghana’s preferred traits for producers, consumers and other value chain actors. Limited information on gene action controlling the inheritance of large seed size confounds the choice of appropriate breeding methods. Generation mean analysis was conducted to identify the gene action controlling the inheritance of cowpea seed size. Data on the seed length, seed width, and seed thickness of five generations (P1, P2, F1, F2, and F3) of a cross between Kansa (large seed-sized variety) and Hewale (small seedsized variety) were analyzed. The scaling test analysis showed additive-additive epistasis, and the additivedominance model was inadequate in explaining the gene action controlling cowpea seed size. Significant additive, dominance, additive-additive, and dominance-dominance gene actions were found to control seed size. Also, allelic and non-allelic gene action were found to control seed size, hence recurrent selection could be used to improve the trait. From this study we conclude that we cannot improve on Cowpea seed size by making between large-seeded lines and small-seeded lines and recommend that breeders should make crosses among large-seeded lines if larger seeds are the desired trait as is the case in Ghana.