Estimates of genetic parameters in a maize composite and potential for recurrent selection

The genetic variability in the maize composite I - Mo, from the improvement program of the Instituto Agronomico de Campinas (IAC), was evaluated. Eight trials of half-sib families with 25 families each, the composite, and a commercial control AL 30 were conducted at the IAC. Individual and combined variance analyses of trials were performed and genetic variance components estimated for ear yield (EY), plant height (PH), and ear height (EH). A high additive variance value was obtained for EY, in contrast to values found in literature, indicating that composites have large variability and are promising for recurrent selection programs. The VC G/VCE index of 0.7 for EY indicated suitability for selection. Assuming a 20% selection of best families, an expected selection gain of 7.9% was estimated. Composite I - Mo has great genetic variability and a remarkable potential for breeding via recurrent selection, promising considerable selection gains in yield.