Generation mean analysis of dual purpose traits in cowpea (Vigna unguiculata [L.] walp)

Abstract

Dual-purpose, the relative ratio of grain to fodder productivity of cowpea (Vigna unguiculata) is one of the major factors affecting the adoption of new varieties in sub-Saharan Africa. Efforts have been made to improve either the fodder or the grain productivity separately. However, there is the need to develop a variety with both good grain and fodder productivity. Gene effects for dual-purpose traits were estimated from the combined analysis of the parental, F₁, F₂ and backcross populations involving one fodder cowpea and two grain type cowpeas with the aim of understanding the genetic basis of these characteristics. The fodder parent had significantly better performance compared to the grain types for all dual-purpose traits. Transgressive segregates for high and low fodder yield were observed, suggesting that the fodder yielding genes were dispersed among the parents. Frequency analysis showed that all the F₂ populations for fodder yield exhibited a continuous distribution, suggesting that inheritance of fodder yield is quantitative in nature and may involve more than two genes. Epistatic effects were found to be important for all dual-purpose traits (days to first flower, plant height, pod weight, leaf weight, branch weight, seed weight, biomass and fodder yield). Fodder yield per plant appeared to be influenced by both additive and non-additive gene effects, whereas grain yield was influenced by complementary gene action. Duplicate gene interaction was predominantly involved in the inheritance of most of the structural traits (plant height, leaf weight and branch weight). For genetic improvement of fodder and grain yield, utilizing non-additive components, intermating among selected segregates in early generation or reciprocal recurrent selection should be effective approaches.

Keywords: Gene effects, fodder, Vigna unguiculata, generation mean analysis