Estimates of heritability and the degree of dominance in corn
1949
Robinson, H.F. | Comstock, R.E. | Harvey, P.H.
A method is outlined for studying the genetic variability in corn by using the data from F2 parent plants and F3 progeny plots of "biparental" crosses in F2 populations. The genetic variance has been divided into additive genetic variance and variance due to dominance deviations. The amount of each has been estimated in three segregating prolific single-cross hybrids. Heritability, which is the ratio of the additive genetic to the total variance, has been estimated for eight characters. Three distinct estimates of the heritability of each character were obtained for the individual hybrids and all hybrids combined. Two of the estimates resulted from parent-offspring regressions and the third was derived from the components of variance of the analysis of the F3 progeny data. The heritabilities of plant height, ear height, husk extension, and husk score were relatively high. The number of ears per plant, ear length, ear diameter, and yield had considerably lower heritability values. The application of such information and the possibilities indicated for improving yield by selection are discussed. The degree of dominance was estimated for genes concerned with the development of each character. Little or no dominance was indicated from the data for genes determining plant and ear height. Husk extension genes were estimated to have complete dominance, while partial to complete dominance was indicated for genes controlling husk score, ear number, ear length, and ear diameter. The possibility of over-dominance in the action of genes determining yield of grain was indicated in this study. However, the situation is postulated whereby individual genes having no more than partial dominance might result in an expression of over-dominance.
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