ESTIMATED GENETIC-VARIABILITY IN A MAIZE INTERPOPULATION

Three procedures were used to obtain estimates of genetic, environmental and genetic .times. environmental variances for 9 traits. The reference population for which the genetic parameters were defined was the interpopulation formed by crossing random individuals in pairs from the 2 populations [Zea mays Iowa two-ear synthetic and pioneer two-ear composite]. Epistasis was assumed to be either negligible or absent. Significant genetic variation and genetic .times. environment interactions existed among the full-sibling progenies for all traits. In the interpopulation, additive genetic variance was the largest component of genetic variability for all traits. Dominance variance was about half the estimates for additive variance. Except for yield, estimates of additive .times. environment interaction variance were much lower than their corresponding estimates of additive genetic variance. There was no definite trend in estimates of dominance .times. environment interaction variance when compared with corresponding estimates of dominance variance. The estimates obtained from the interpopulation were similar to those reported for intrapopulations of maize. The estimates of additive genetic variance for yield were used to predict future progress from reciprocal full-sibling selection. The observed and predicted response for the cycle crosses were very similar, indicating that the observed response was similar to the predicted response based on the interpopulation estimates of the additive genetic variance.