Potencial genético de linhagens de feijão-comum preto desenvolvidas em sistemas com fixação biológica de nitrogênio

Abstract

Common bean (Phaseolus vulgaris L.) is a crop of great importance for food security and the Brazilian economy; however, its production still largely depends on mineral nitrogen fertilization due to the low efficiency of biological nitrogen fixation (BNF). This dependence increases production cost and generates environmental impacts, highlighting the need to develop cultivars with greater efficiency for BNF and better adaptation to sustainable cropping systems. The objective of this study was to evaluate the genetic potential of black common bean lines developed under exclusive BNF systems, considering their responses to mineral nitrogen fertilization and rhizobial inoculation, aiming to select genotypes with high yield stability and promising nodulation traits. Fifteen lines derived from the BRS FP403/BRS Esplendor population selected over successive breeding cycles conducted without the use of nitrogen fertilizers, were evaluated. Field experiments were carried out in a randomized complete block design with three replications across seven environments under two nitrogen sources (mineral nitrogen fertilization and rhizobial inoculation). The evaluated traits included grain yield (GY), 100-grain weight (HGW), sieve yield (SY), visual grain score (VGS), percentage of nitrogen derived from the atmosphere (%NDFA), chlorophyll content (CC), and total nitrogen (TN). Two greenhouse experiments were conducted under rhizobial inoculation using a randomized complete block design with four replications. Total dry matter (TDM), number of nodules (NN), nodule dry matter (NDM), specific nodule mass (SNM), and nodular area (NA) were evaluated. Individual and combined analyses of variance were performed, along with adaptability and stability analyses using the WAAS/WAASY method, correlation analyses among traits, and application of the multivariate selection index MGIDI. Overall, the results confirm the existence of wide genetic variability among the evaluated black common bean lines, both for productive traits and for attributes associated with biological nitrogen fixation. Evaluation under contrasting nitrogen supply conditions allowed the identification of lines with consistent performance under BNF, particularly CNFP 21675, CNFP 21640, CNFP 21660, CNFP 21685, and CNFP 21629, which combined good agronomic performance with greater stability across environments. The efficiency of adaptability and stability indices reinforces the feasibility of selecting superior genotypes in systems based exclusively on BNF. These results demonstrate that conducting selection under this system is a promising strategy for developing cultivars adapted to more sustainable production systems, with reduced dependence on mineral nitrogen fertilizers and potential mitigation of environmental impacts.