Heterosis and Combining Ability in Barley1

Abstract

Eight parental varieties of barley and the 28 possible F1 and F1 populations were evaluated in spaced plantings in two environments. The traits studied were yield, kernel weight, kernels per head, heads per plant, and height.The average heterosis values of F1's based on midparent means for yield, kernel weight, kernels per head, heads per plant, and height were 21.5, 5.9, 7.1, 7.6, and 3.2%, respectively. When the F1's were compared to the high parent, the average heterosis for yield was 9.1%. The average inbreeding depression for yield in the F2 generation was 26.1%General and specific combining ability variances were obtained from the F1 data, using Griffing's experimental method 4, model II. A substantial amount of additive and nonadditive genetic variance for yield was indicated. Most of the genetic variance for kernel weight, heads per plant, kernels per head, and height was additive.The yield of the best hybrid exceeded the highest yielding parental varieties, Liberty and Traill, by 22 and 38%, respectively. A hybrid advantage of this degree combined with evidence of considerable nonadditive genetic variance for yield indicates the desirability of additional research on hybrid barley. The results reported indicated that performance per se can be used as a basis for initial screening in evaluating potential parental varieties for use in a hybrid breeding program.