Potencial de cruzamentos simples e duplos na seleção para múltiplos caracteres no feijoeiro

Abstract

The choice of segregating populations is an important step in a common bean breeding program. However, there are still some questions about what would be the best kind of population to be used. The objective of this study was to compare segregating populations from single crosses and double crosses, aiming to verify which kind of population generates the best inbred lines, when the selection is done based on multiple traits simultaneously. As genitors it were used six inbred lines with “carioca” grain type. It were evaluated progenies from six populations, four single crosses (SC) and two double crosses (DC), in six environments. It was evaluated the same number of progenies of single and double crosses, 50 progenies of each SC and 100 progenies of each DC. The following traits were evaluated: plant architecture, plant disease severity in the field, grain type and grain yield. The data of each trait were standardized and then the sum of the standardized variables ( ) index was obtained. The joint analysis of variance was done and some genetic and phenotypic parameters were estimated. It was observed that the single crosses did not differ of the double crosses regarding the mean (SC=36 and DC=36), the heritability (SC=69,2% and DC=68,3%) and the expected gain with selection (SC=5,1% and DC=5,2%), and also the efficiency of the was verified. Double crosses are not the best alternative, even when the selection is based on multiple traits simultaneously, since genitors with favorable phenotypes for the traits under selection are chosen.