Inter-character relationships and heterosis observed in opaque-2 maize crosses and in their normal analogues.

Hybrids obtained from two series of diallel crosses made between six o 2 converted inbred lines on the one hand and their normal analogues on the other were compared for twenty-five characters including yield and several of the yield components, including the parents. Observations on simple inter-character correlation coefficients presented here have shown that the majority of the correlations at the o 2 level are of the same order as at the normal level. A number of correlations of the o 2 type are inferior to those of their normal analogues, whereas a few are favoured by the o 2 gene including the correlation of grain yield with kernels per row. A measure of heterosis for each hybrid over its mid-parent also demonstrated that the o 2 types show poorer heterosis in more cases than do their normal counterparts. Still, in nearly 40 percent of the cases the o 2 hybrids were found to be more heterotic than their normal analogues, particularly for the various maturity characters and several of the yield components. Thus, the possibility of improvement exists in breeding maize with the opaque-2 gene.