Three cycles of selection among and within families in the maize population BR 5011 in the northeast of Brazil

Three cycles of selection among and within families, from 1985 to 1988, were completed in the maize (Zea mays L.) population BR 5011, at the locations of Gararu, Propria and Poco Verde, in the semi-arid region of the State of Sergipe, in order to increase yield and adaptation, field trials were conducted for progeny evaluations using two simple lattice 10 x 10, and 10% selection intensity was used for recombination of the best progenies, in the same year. The estimate of the additive genetic variance in the base population BR 5011 cycle 0 was 94% greater than the high best value found in the Brazilian literature. Its selection decreased in the first and second cycle and the decrease was more evident in Poco Verde mainly due to water stress in the location. The high genetic variability expressed in BR 5011 associated with the relatively high mean yield indicates the great potential of this population for breeding purposes. The expected mean gains through selection among and within progenies was 12.76% per year. The high progeny x location interaction showed the importance for progeny evaluation in more than one location, to incresase the efficiency of the process and to obtain more accurate estimates of variances.