Three cycles of selection among and within half-sib families in the EEL4 maize population

Abstract

Three cycles of selection among and within half-sib families were evaluated on the EEL₄ maize population, in the north, south, and highland regions of Espírito Santo State, Brazil, from 1985 to 1988. Year by year, two hundred families were evaluated using two 10 x 10 lattices, with two replications. For the crossover, the selection rates of 15% among progenies, and 12.5% within progenies, were used. For the trait ear weight, the analysis of individual and combined variance detected highly significant differences for progenies and for the interaction of progenies x locations. The progenies presented, on the average, a good performance, producing at the first, second and third cycles 91.0 g, 129.3 g and 153.5 g per plant, respectively. The heritability values, stricto sensu, varied for locations and cycles, ranging from 12.0% to 44.0%. On average, those values reached 28.5%, 12.0% and 26.2%, from the first to the third cycles, respectively. The magnitudes of the genetic parameters, specially at the third cycle, express the population variability that, associated to high means of progenies productivity, indicate the importance of this population in a breeding program. Mean genetic gains expected with selection combined per cycle, from first to third cycles, were 6.5%, 3.0% and 4.0%, respectively. Therefore, if selection was practiced per location, this value could reach up to 12.3%.