Genotype, genotype × environmental and environmental effects on grain yield and related characters of cowpea (Vigna unguiculata (L.) Walp.)

Abstract

Genotypic, environmental and genotype x environmental interaction variances of grain yield and related characters were estimated in six diverse lowland environments in Papua New Guinea. The genotypic variance of grain yield for six diverse genotypes accounted for only 0.2% of overall variance and was not significant against genotype x environment interaction. The relative merits of alternative selection criteria, viz. pod number per plant, seed number per pod, mean seed weight, pod length and main stem height were assessed. Environmental effects of grain yield accounted for 82% of total variance, and two factors associated with moisture and soil conditions were isolated as the major causes of this variation. Genotype × environment interaction effects were analysed by joint regression analysis, and the applicability of the analysis to tropical areas with low levels of management is discussed.