Implicações da seleção precoce para cor de grão do feijão no teor de ferro e zinco e na produtividade

Abstract

In Minas Gerais, and in most regions in Brazil, the preference is for the carioca type bean. Thus, for the improvement of any characteristic, it is important that the evaluated progenies be of this type of grain. However, it is questionable whether the early selection for the carioca grain type can interfere with the successful selection for other traits of interest. The objectives of this study were: to determine if early selection for grain type affects iron and zinc content, as well as grain productivity; verify whether a correlation exists between these features; and obtain carioca type bean lines with high iron and zinc content and grain productivity. We used a population derived from a cross between P - 180 (carioca grain type) x Paraná (brown beans) lines, previously identified as promising for obtaining lines with high iron and zinc content. This population was advanced in bulk up to the F3 generation. In this generation we opened the bulk, selecting 96 individual plants, originating progeny F3:4. Of the 96 progenies, 48 were selected by the carioca grain type and the other 48 by any kind of grain. The F3: 4 progenies were evaluated in Lavras, MG, and progenies F3:5 and F3:6 in Lavras and Patos de Minas, in regard to iron and zinc content in grains, as well as grain productivity. We performed individual and combined variance analyses, estimated for each trait and type of progeny heritability, expected gains with selection and phenotypic correlation between traits. We concluded that: early selection for bean grain type does not affect zinc content or grain productivity of the obtained progenies; there is a positive correlation between iron and zinc content in the bean grains, however, these minerals present negative correlation, although in low magnitude, with grain productivity; it is possible to obtain bean lines combining high iron and zinc contents and productivity, as long as we use a selection index.