Seleção recorrente para altas concentrações de ferro e zinco em feijão-comum do grupo preto

Abstract

Iron and zinc deficiency in the human diet is a public health issue, affecting millions of people worldwide. To minimize this problem, one viable alternative is the development of cultivars capable of accumulating high concentrations of these nutrients in the grains. However, breeding for high iron and zinc concentrations is complex due to the quantitative nature of these traits. This study aimed to conduct a recurrent selection program, obtaining common bean progenies of the black group with high iron and zinc concentrations, while maintaining genetic variability and desirable agronomic characteristics. The population evaluated in this study was obtained through the intercrossing of eight parents selected in the first cycle of recurrent selection for high iron and zinc concentrations in common bean of the black group, with two elite lines added to the crossing scheme. Thirty progenies were evaluated along with four controls (BRS Esteio, BRS FP417, CNFP 18133, and BRS Supremo) in Santo Antônio de Goiás - GO (winter/2023) and Ponta Grossa - PR (rainy season/2023 and dry season/2024). The experiments were conducted in a randomized complete block design with three replications and plots provided by three three-meter rows. The evaluated traits were: productivity (kg ha-1), 100-grain weight (M100 - g), iron concentration (CFe - mg kg-1), and zinc concentration (CZn - mg kg-1). Phenotypic data were subjected to analysis of variance, and genetic parameters were obtained. Estimates of genetic divergence were obtained using the Rogers distance modified by Wright. Cluster analysis was applied using the UPGMA method. Through cluster analysis, the progenies were grouped into four groups. A significant effect was observed in the analysis of variance, highlighting the existence of genetic variability among the progenies for the four evaluated traits. The coefficients of variation ranged from 4% to 14%, and the selected accuracy estimate ranged from 0.59 to 0.96, decreasing good experimental precision. The heritability estimate was high for productivity (82%), M100 (96%), and CFe (79%), but low for CZn (43%). The gains from direct selection were 9.5% for productivity, 7.6% for M100, 4.6% for CFe, and 2.4% for CZn. Simultaneous selection provided gains of 2.9%, 3.6%, 2.3%, and 1.3% for productivity, M100, CFe, and CZn, respectively. Considering the molecular groups and phenotypic traits, 10 progenies were selected to be used for recombination and the formation of the new cycle. The selected progenies obtained averages of 2273 kg ha⁻¹ (productivity), 24.7 g (M100), 72.8 mg kg⁻¹ (CFe) and 31.2 mg kg⁻¹ (CZn), exceeding the averages of the reference cultivar BRS Supremo in all evaluated classifications.