Alectra vogelii (benth) is parasitic weed which causes significant yield reductions in cowpea (Vigna unguiculataWalp) in Africa. The objective of this study was to identify the type of gene action controlling the trait for resistance to Alectra vogelii in cowpea and estimate the heritability of the trait. Seven genotypes of cowpea were mated in half diallel and their F 2 progeny, including parents, were evaluated for reaction to Alectra vogelii infection in the field in two locations at Ilonga and Hombolo Agriculture Research Stations. Highly significant (P < 0.001) differences were found for Alectra emergency and infestation at Ilonga. General combining ability (GCA) and specific combining ability (SCA) effects for Alectra shoot emergency and infestation were significant (P < 0.05). The estimate of Baker's ratio for Alectra shoot emergency and infestation were 0.62 and 0.66, respectively. This indicates that both additive and non-additive gene actions influenced the trait for resistance to Alectra emergency and infestation. Narrow sense heritability estimates were 41.28 and 44.39 for shoot and emergency, respectively. These results imply that introgression of a desirable trait in an elite genotype would involve careful crossing with a resistance genotype, accompanied by selection in the advanced population.

Abstract-Alectra vogelii (benth) is a parasitic weed which causes significant yield reductions in cowpeas (Vigna unguiculata Walp)