Selection indexes based on genotypic values applied to Brazilian tropical wheat breeding

Abstract

Although Brazil is one of the main agricultural countries in the world, it is historically an importer of wheat. For this reason, strategies aimed at the expansion of wheat in the country, to areas that are not traditionally producing (warmer), are of paramount importance. In wheat breeding, phenotypic values ​​are usually used in simultaneous selection, however, they do not always correspond with genetic superiority. Therefore, the objective of this work was to evaluate the efficiency of five selection indexes applied to the genotypic values ​​of wheat, the coincidence between the indexes and to select the most promising lines. For this, we evaluated a panel with 41 genotypes of tropical wheat, for the traits: days for flowering, disease note, plant height, hectoliter weight and grain yield. Data were submitted to REML/BLUP analysis to estimate genetic parameters and genotypic values. We applied on the BLUPs the rank summation index, multiplicative index, genotype- ideotype distance index, additive index and FAI-BLUP index. There is a genotypic variation shown by analysis of deviance for all evaluated traits. We presented different estimates of gains from selection according to the selection index applied. We observed higher estimates of gains from selection for additive and genotype-ideotype distance indexes. High similarity was observed in the selection of genotypes through the coefficient of coincidence between the indexes. Eight lines were selected simultaneously by three or more indexes. Lines VI 14047, VI 14774 and VI 14980 showed the best performance among the eight lines evaluated by the Z index.