Genetic analysis of yield component traits in cowpea [Vigna unguiculata (L.) Walp.]

We investigated the genetic control of the three yield components in cowpea: number of grains per pod, pod length and grain size, in a biparental cross. Genetic parameters were estimated in generations of a cross between two contrasting genitors, using a randomized complete block design with three replications. Narrow-sense heritability estimates varied from 27% to 67%, suggesting that genetic gains can be achieved with selection. Pod length and grain size had the highest heritability values and genetic gains. The number of grains per pod is highly affected by the environment. Dominance was detected for all traits, mainly for pod length. However, additive gene effects accounted for more than 68% of the variation in all traits, which are controlled by at least 10 genes. It is possible to improve the evaluated traits via conventional breeding approaches, although large population sizes will be required in breeding stages.