Combining Abilities and Relative Dominance among Maize Inbreds for Resistance to Earworm Injury1
- Neil W. Widstrom and
- John J. Hamm2
General combining ability effects for corn earworm, Heliothis zea (Boddie), resistance were highly significant and accounted for approximately two-thirds of the genetic variability measured in two sets of diallel crosses among sweet corn, Zea mays (L.)> inbreds. Specific combining ability estimates were generally low, though significant in one case. Highly significant genotype-environment mean squares were attributed to the interaction of general combining ability with location and years. The relative importance of location effects was essentially equivalent to those for years.
Trends among constant parent regression coefficients were essentially absent, suggesting a low level of dominance for resistance to earworm injury. Dominance estimates for individual inbreds and average estimates as obtained from variance component ratios for diallel sets were also in the partial dominance range. Estimates of heritability for selection of half-sib families were .340 and .398 for the nine-line and 12-line sets, respectively. Although heritabilities of this size should make reasonable selection gains possible, culling F1's with large noncomplementing specific combining ability effects from selected half-sib families of high general combining ability would further enhance potential selection gains.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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