Abstract
Eight selected cowpea were evaluated in four environments of rainforest and humid savanna agroecology to determine the grain yield and the response patterns. A regression method and a genotype-grouping technique were employed in the evaluation. The results showed significant variations in the variety, environment and variety * environment interaction. The regression analysis and cultivar grouping technique are similar as they both identify more stable and less stable cultivars across diverse environments. Thus, genotype IT84s – 2246, IT85D – 3577 and IT86D – 1010 were considered stable in the two-agro ecological zones. Using the regression and cultivar grouping techniques.
Keywords: Vigna unguiculata, stability, regression, Genotype-grouping technique.