Seleção de linhagens de feijão de alto desempenho agronômico e biofortificadas para potássio, fósforo, zinco e cobre

Abstract

Considering the expansion of grown of common bean for large mechanized areas and the need of biofortication of basic foods consumed by the Brazilian population, to minimize minerals deficiencies, obtaining common bean lines with high agronomic performance and higher minerals concentration in the grains represents technological advances for the culture. The objectives of this study were: (1) to estimate the genetic parameters for morphological, phenological, grain yield and nutritional characters in four biofortified populations of common bean in F6:8 generation; (2) assess the effectiveness of different selection strategies, direct selection and selection indexes, with the adoption of economic weights equivalent to coefficient of genetic variation (CVg) and proportional to a gain of 10% in average for each character, without restriction and also restriction to gains in only one of the mineral; and (3) to select common beans lines of high agronomic performance, as erect architecture and grain yield, and biofortified for potassium, phosphorus, zinc and copper concentrations in grains. Thus, a total of 169 common beans lines in F6:8 generation were evaluated in two experiments in a simple lattice design in the rainy season 2012/2013 and dry season 2013, in Santa Maria/RS. The following traits: note lodging, general adaptation note, insertion height of the first and last pod, cycle, number of pods and grains per plant, weight of 100 grains, grain yield and potassium, phosphorus, zinc and copper concentrations in grains were evaluated and the genetic parameters were estimated in each biofortification population. For simultaneous selection were tested selection indexes: direct selection, classical index, base index, parameters and weights-free index, based on desired gains index, multiplicative index and the "ranks" sum index. Significant line x environment interaction was observed for most of the characters, except for potassium, phosphorus and copper concentrations in grains. Genetic variability has not been obtained only for the copper concentration in grains. The weight of 100 grains and grain yield show high heritability in F6:8 generation in all populations studied. The characters of note lodging, height of the first pod, cycle, number of pods per plant and number of grains per plant were from moderate to high heritability. The others characters have from low to high heritability, except for the potassium and zinc concentrations in grains that exhibit from low to moderate heritability. The direct selection enabled high gain selection for individual characters, but caused undesirable changes in other characters under selection. The multiplicative index is the best strategy for simultaneous selection for the identification of common beans lines for erect architecture, high grain yield and high potassium, phosphorus and zinc concentration in grains. The L92, L 97, L 137 and L 146 lines are promising and remain under evaluation by the breeding program.