Inheritance of resistance to Alectra Vogelli in cowpeas(Vignamunguiculata[L} Walp.)

Abstract

Alectra vogelii (benth) is a parasitic weed which causes significant yield reduction in cowpea (Vigna unguiculata Walp) in Tanzania. The objective of this study was to (i) identify the type of gene action controlling the trait for resistance to Alectra vogelii in cowpeas and its heritability (ii) determine the effect of Alectra vogelii infestation to yield, yield components and seed protein content. Seven genotypes of cowpea were mated in half diallel and their F2 progeny including parents were evaluated for reaction to Alectra vogelii infection in the field in two locations using Randomized Complete Block Design (RCBD) with three replications. High significant (P < 0.001) differences were found for Alectra emergency and infestation at Ilonga. General combining ability (GCA) effects and specific combining ability (SCA) effects for both Alectra emergency and infestation were significant (P < 0.001) and P < 0.05 respectively). The estimate of Baker’s ratio for Alectra emergency and infestation were 0.62 and 0.66 respectively. Thus indicating that both additive and non-additive gene actions influenced the trait for resistance to Alectra emergency and infestation with additivity being predominant. Narrow sense heritability estimates were found to be 0.41 and 0.44 respectively. Correlation between Alectra infestation and emergency with yield components revealed that the number of pods were the most negatively affected (P < 0.001). This implies that indirect breeding for resistance or tolerance to Alectra infestation can endeavor to screen or breed for cultivars with high number of pod. The finding on Baker’s ratio means crossing carefully selected genotypes with resistance gene followed by selection at early segregating generation is the best method for improving this trait for resistance to Alectra vogelii in cowpea.