Stability analysis of dry matter and seed yield of cowpea [Vigna unguiculata (L.) walp.] genotypes in humid and lowland areas of southwestern Ethiopia

Abstract

Cowpea is a multi-purpose legume interested in dealing with genotype and genotype-by-environment interaction which has a significant impact on the success of breeding method. Twelve cowpea genotypes were examined across three experimental sites in Southwest Ethiopia through the cropping seasons in 2020 and 2021. A randomized complete block design (RCBD) with three replications for each location was applied to complete the trials, and the dry mater and seed yields were recorded and analyzed using AMMI and GGE biplot models. Dry matter yield (DMY) was significantly influenced by genotype (35.51 %), environment (34.25 %), and genotype by environment (G × E) interface (24.82 %), according to the combined analysis of variance. On the other hand, seed yield (SY) was highly influenced by the environment (39.93 %), genotype-environment (G × E) (19.08 %), and genotype (11.88 %). For both dry matter and seed yield, the investigated genotypes were divided into four mega-environments using AMMI and GGE biplot. The initial mega-environment contain E6, the subsequent contain E3 and E5, the third one has E1 and E2, and the final mega-environment hold E4 for dry matter and E3, E4, and E6, E5, as well as E1, and E2 for seed yield. The GGE biplot revealed that the three vertex genotypes for dry matter yield, G6, G7, and G10 whereas, six vertexes for seed yield G2, G6, G8, G7, G11, and G10, scored higher yield in corresponding environment, while the AMMI model showed G4, G6, G9, and G10 were comparably stable and high yielders for DMY and G4, G5, and G9 were for SY, whereas G6 and G7 had the highest SY but were unstable genotypes. Based on the AEC line, genotypes represented by G4, and G9 were relatively stable and high yielders for both DMY and SY. The selected genotypes could be suggested for variety development in the region.