Maize (Zea mays L.) breeders emphasize selection within F2 populations derived from crosses of inbred lines: Studies of the inheritance of quantitative traits in maize have been conducted primarily for generically broad-based populations. Objectives of our study were to estimate the generic variability in F2 populations developed from crosses of related and unrelated lines and to determine the effects of five generations of random intermating of plants within F2 populations on the estimates of genetic variability. Estimates of additive genetic variability were greater in the unrelated line crosses, but the estimates were not significantly different before and after random intermating within both crosses. Estimates of dominance variance decreased with random mating, suggesting that linkage effects were affecting the estimates. For applied breeding programs, it seems that adequate genetic variability was available in both types of crosses and that five generations of random intermating were not effective for increasing genetic variability
