Abstract
INTRODUCTION: Common bean (Phaseolus vulgaris L.) is a key source of dietary protein and micronutrients, in low- and middle-income countries. Improving both yield and micronutrient density requires a clear understanding of genotype (G), environment (E), and genotype-by-environment interaction (GEI) effects to support nutrition-sensitive breeding strategies. METHODS: This study assessed the effects of G, E, and GEI on grain yield and micronutrient concentration using the Additive Main Effects and Multiplicative Interaction (AMMI) model. A total of 83 bush and 84 climbing common bean genotypes were evaluated across three locations and two cropping seasons (2024A-2024B) in Burundi. AMMI and GGE biplot analyses were applied to examine genotype performance, stability, and adaptation across environments. Broad-sense heritability was estimated for yield and micronutrient traits, and a multi-trait selection index (MTSI) was used to identify superior genotypes combining agronomic and nutritional attributes. RESULTS: Combined AMMI-analysis revealed highly significant (p <0.001) effects of genotype and environment on grain yield, iron (Fe), and zinc (Zn), together with significant GEI for most traits. Significant genetic variation was observed for Fe (52.86-76.5 ppm in bush beans; 53.38-59.7 ppm in climbing beans), Zn (≈17-23 ppm), and grain yield (≈950-2240 kg ha(-1)). Several genotypes surpassed check varieties for Fe and Zn, though enhanced micronutrient levels were not consistently associated with high yield. AMMI and GGE biplots identified both stable, high-performing genotypes and those with specific environmental adaptation. Broad-sense heritability was high for Fe and Zn (h(2) = 0.68-0.82) but low for yield (h(2) ≈ 0.30-0.33). The multi-trait selection index (MTSI) effectively identified genotypes combining good yield and micronutrient density. DISCUSSION: These findings highlight the importance of integrated multi-environment evaluation and multi-trait selection for developing high-yielding, micronutrient-dense common bean varieties adapted to diverse agro-ecologies.