Seleção simultânea de progênies de meios irmãos de milho com adubação e sem adubação fosfatada

Abstract

The selection of superior genotypes in corn can be performed on the basis of selection indexes. This methodology has been efficient to obtain superior genotypes, since it allows prediction simultaneously gains for characters of agronomic importance. In this way, the objectives of the present work were to evaluate the percentage and total gain with the selection of 250 progenies of half sibs and six controls, based on selection indexes; to evaluate the correlations between the characteristics evaluated, and to estimate the most important genetic parameters in an environment with presence and absence of phosphate fertilization. For this purpose, 250 progenies of half siblings were selected from the random crossbreeding of five maize varieties, which showed good development in the environmental conditions of Mato Grosso do Sul. Later, these progenies were evaluated in two environments (in the presence and absence of phosphate fertilization). The experiments were installed in a simple lattice incomplete blocks design with two replicates. The evaluations made in the progenies of half siblings were grain yield, ear height, plant height, stem diameter, female flowering, male flowering, flowering interval, ear diameter and ear length. The analysis of variance performed, and later the estimated genetic parameters showed a differentiated behavior of the progenies based on the environmental conditions of presence and absence of phosphate fertilization. For the prediction of gains with the use of selection indexes the progenies were submitted to a selection intensity of 20%, four selection indices methods with five different economic weights were used. The results indicate that greater prediction of grain yield gains with the method of Mulamba and Mock in the absence of phosphate fertilization, and in the presence of fertilization.