Additive and Nonadditive Genetic Effects on Biological Nitrogen Fixation in Common Bean

Common bean grain yield is strongly influenced by nitrogen availability and can be improved through biological nitrogen fixation (BNF), which among cultivars and Rhizobium strains. This study evaluated the BNF ability of 15 common bean cultivars and their symbiotic performance with three Rhizobium strains, including a strain authorized by the Brazilian Ministry of Agriculture, to identify variability for breeding strategies and select promising inoculants. A greenhouse experiment was carried out, and data were subjected to variance analysis, with means compared by the Scott–Knott test at 5% probability. A partial diallel analysis was also performed to estimate general and specific combining ability. Based on these results, seven cultivars and two strains (UFLA 02-100 and CIAT 899) were selected for field evaluation. BNF was influenced by genotype, strain, and genotype × strain interaction, and traits related to BNF were controlled by both additive and non-additive genetic effects. Inoculation with Rhizobium promoted grain yield comparable to nitrogen fertilization. The cultivar BRSMG Zape showed superior grain yield and high general combining ability, indicating its potential for breeding programs aimed at improving BNF. The strain UFLA 02-100 resulted in higher grain yield than the reference strain CIAT 899, suggesting its potential as a recommended inoculant for common bean production.