Genotype x environment interaction and stability analyses of grain yield and micronutrient (Fe and Zn) concentrations in navy bean (Phaseolus vulgaris L.) genotypes under varied production environments

Abstract

Development of stable, high yielding and micronutrient dense bean cultivars offers a sustainable solution to the challenge of malnutrition in developing countries. The objectives of this study were to evaluate the effects of genotypes, environments and genotype by environment (GEI) on iron (Fe) and zinc (Zn) in grain and grain yield (GYD) in navy bean genotypes, identify genotypes with high adaptability and stability for high grain Fe, Zn and GYD, and study the associations among grain Fe, Zn and GYD. The study was conducted in four locations over two seasons (2018/19 and 2019/20) resulting in eight environments (year-location combinations). Eight-four breeding lines and check cultivars were field-tested using a 12 × 7 alpha lattice design. The GEI was highly significant (p < 0.001) for GYD but not significant for grain Fe and Zn. Grain yield ranged from 2002 (G65) to 2501 (G27) kg/ha and was largely influenced by environment (38.87%) and the GEI (39.48%). Grain Zn and GYD had the largest heritability estimates of 0.82 and 0.60, respectively. The largest variance was observed on Fe, which ranged from 86.5 (G63) to 119.78 ppm (G37). Highly significant and positive associations (r = 0.52, p < 0.001) were observed between Fe and Zn. Stability analysis using additive main effects and multiplicative interaction (AMMI), AMMI stability value (ASV) and Yield Stability Index, identified six genotypes (G12, G66, G69, G39, G38 and G3) with high GYD, good GYD stability and desirable grain Fe and Zn concentrations above breeding targets of 95 and 40 ppm, respectively. These genotypes should be used as parents for crossing with other cultivars to improve micronutrient density, GYD and GYD stability. The vertex genotypes G27, G24 and G33 combined specific adaptation and high GYD with desirable micronutrient density as revealed by the “which-won-where” polygon-view of GGE biplot. These genotypes could be recommended for deployment in their respective mega-environments.