Seleção indireta para o número de grãos por vagem e tamanho dos grãos visando a produtividade em soja

Abstract

In soybeans, potential grain productivity is dependent on the number of plants per area, number of pods per plant, number of grains per pod and the average weight of the grains. Due to the importance of this crop on the world stage, it is necessary to constantly invest in new genetic improvement and management technologies, aiming to increase gains in grain productivity. Thus, the objective was to study the genetic and phenotypic parameters and the correlation between the characters weight of a thousand grains, number of grains per pod, leaf area and grain productivity in soybeans and identify which selection strategy is most efficient to increase soybean productivity grains. To obtain the segregating population, two contrasting cultivars were used for the characters grain size and number of grains per pod. The F2 population was conducted in Bulk. At physiological maturity, individual plants were harvested and classified according to sieve yield. The F2:3 and F2:4 progenies were conducted and evaluated in the 2021/22 and 2022/23 agricultural years. The following characters were evaluated: days to flowering, type of leaflet, absolute maturation, plant height, insertion height of the first pod, lodging index, number of pods per plant, number of grains per pod, weight of a thousand grains and grain productivity. Statistical analyzes were performed with the aid of the R statistical environment, using a mixed model approach (REML/BLUP). The contribution of the production components to grain productivity varied depending on the progeny, showing that the genotype with the greatest equivalence between the components is not always the one with the highest productivity. The weight of a thousand grains and the number of grains per pod showed an inverse relationship. This relationship indicates that, when the grains are larger, that is, they have greater individual weight, the number of grains per pod tends to be smaller, and vice versa. Thus, an increase in grain size can lead to a decrease in the total number of grains formed per plant. Indirect selection, considering the characters number of grains per pod or grain size, was not the best strategy to increase productivity in soybean cultivation, due to the complex interaction between the different production components. Therefore, the best approach to selecting superior soybean lines is to focus directly on grain productivity, as this strategy takes into account the interaction that exists between the different factors that affect productivity and, accordingly, allows the identification of superior genotypes more effectively.