Integrated AMMI, GGE Biplot, and MTSI analyses reveal yield stability and adaptation patterns in cowpea in Ghana

Genotype × environment interaction (G×E) complicates the identification of high-yielding and stable cowpea genotypes across variable production environments. This study evaluated 20 advanced cowpea breeding lines for grain yield, stability, and multi-trait performance across five location-year environments in Ghana during the 2024 and 2025 cropping seasons.

Trials were conducted using a randomized complete block design with three replications. Both seasons were drought-prone, although moisture stress varied among location-year environments because of erratic rainfall distribution. Grain yield was analysed using additive main effects and multiplicative interaction (AMMI) and genotype plus genotype × environment (GGE) biplot analyses, while grain yield, biomass yield, harvest index, hundred-seed weight, and days to 95% pod maturity were integrated using the Multi-Trait Stability Index (MTSI).

Analysis of variance revealed significant (p < 0.001) effects of environment, genotype, and G×E. The first two interaction principal components explained 92.15% of G×E variation, with Wa_2025 showing the largest IPCA1 score. Tuzievallenga had the highest mean grain yield (1149 kg ha^-1), whereas IT17K-2030-2 had the lowest AMMI Stability Value (ASV = 114.54). Five genotypes combined high yield with relative stability: Tuzievallenga, IT17K-2030-2, IT17K-1095-2-2, IT17K-849-2-1, and IT17K-1802-1. MTSI values ranged from 2.035 to 5.518, with IT17K-1095-2-2, IT17K-849-2-1, IT17K-1403-1-1, IT17K-2024-4, and Tuzievallenga having the lowest values. IT17K-1095-2-2, IT17K-849-2-1, and Tuzievallenga were common to the top five selections from both approaches. GGE identified one common sector comprising Damongo_2024, Manga_2025, and Nyankpala_2024, with Tuzievallenga as the winning genotype, while Wa_2025 and Nyankpala_2025 formed distinct sectors associated with SARI-tuya and IT17K-1266-2-1, respectively.

The findings demonstrate substantial G×E differentiation and identify promising genotypes for farmer-managed on-farm evaluation and complementary use in cowpea breeding.