Abstract

Maize is an important cereal crop in scientific research area and the world economy, where Brazil is one of the leading producers. High production and productivity are partly due to plant breeding programs, where the selection of superior genotypes is based on indexes. This strategy has been very efficient o obtaining superior genotypes since there are simultaneous gains for various agronomic and economic characters. The aim of the research was to measure genetic gain through inbred selection based on the selection index, as well to compare the efficiency of the different index in order to verify which one is more recommended to a phenotypic selection of maize inbreeds. To achieve this, 256 inbreeds were experimentally evaluated in 12 environments. The characters evaluated were grain yield, fecundity, lodging and breaking plant, plant height, ear height, relative position of the ear, male and female flowering and the flowering interval. Selection intensities of 10 and 20% were applied in the direct selection in seven study indexes. The analysis showed that the direct selection of the characters was not effective for the selection of superior maize genotypes. and the Smith and Hazel's index and Williams's index got higher gains yield for the genotypes evaluated.

Key words: direct selection, obtaining hybrids, pure lines, Zea may L.