II. 26. The inheritance of harvest index in barley.
M.A. Khalifa, Agronomy Department, Faculty of Agriculture, Assiut University, Assiut, Egypt, A.R.E.
Relatively little effort has been directed toward the selection, inheritance and evaluation of modern cultivars on the basis of their harvest index. The improvement in grain yields in Australian oat cultivars has been due almost entirely to an increased harvest index without an increase in biological yield (Sims, 1963).
Modern high-yielding cultivars of barley and spring and winter wheat in Britain show a higher harvest index than previous cultivars (Watson, Thorne and French, 1958 and 1963).
Singh and Stoskopf (1971) found that harvest index was positively correlated with grain yield, also harvest index shows a positive genotypic correlation with grain yield, but a negative genotypic correlation with heading date and height in oats (Rosielle and Frey, 1975).
Moreover, Rosielle and Frey (1975) used the harvest index as a secondary trait in their restricted selection index for improving grain yield in a population of 1,200 F9 derived oat lines. They found that the efficiency of the selection was 70% improvement in grain yield.
Bhatt (1976) reported that gene action governing the expression of harvest index was largely additive, but nonadditive gene action was obtained in some crosses. Heterosis for harvest index was found to be present in all crosses. Also Rosielle and Frey (1977) concluded that harvest index showed primarily additive gene action, although this conclusion was complicated by the occurrence of negative skewness. They added that crosses between higher harvest index parents tended to show small phenotypic variation for harvest index and other traits, in a study of the inheritance of harvest index and its components in 15 crosses among 30 oat lines.
This investigation presents an analysis of a diallel set of crosses to evaluate the genetic system controlling harvest index, biological yield and grain yield of six spring barley genotypes (Table 1).
Table 1. List of spring barley genotypes used as parents in diallele crossing programme.
The genetic system controlling plant weight "biological yield," weight of grain and straw per plant and harvest index in six genotypes of barley was analysed using data from the F1 and F2 generations of a diallel cross. From the Wr Vr graphs and the analysis of genetic components it was evident that additive and nonadditive were the most important components controlling variation in all characters. The F1 progeny of all parents showed marked heterosis (Table 2) for the expression of biological yield and economic yield.
From the diallel graphs it was evident that dominance and nonallelic interaction combined to give these heterotic effects. Heritability estimates indicated that effective selection could be practiced for harvest index in segregating populations from crosses including Zephyr in it.
References:
Bhatt, G.M. 1976. Variation of harvest index in several wheat crosses. Euphytica 25:41-50.
Rosielle, A.A. and K.J. Frey. 1975a. Estimates of selection parameters associated with harvest index in oat lines derived from a bulk population. Euphytica 24:121-131.
Rosielle. A.A. and K.J. Frey. 1975b. Application of restricted selection indices for grain yield improvement in oats. Crop Sci. 15:544-547.
Rosielle, A.A. and K.J. Frey. 1977. Inheritance of harvest index and related traits in oats. Crop Sci. 17:23-28.
Sims, H.J. 1963. Changes in the hay production and the harvest index of Australian oat varieties. Aust. J. Exp. Agr. Animal Husb. 3:198-202.
Singh, I.D. and N.C. Stoskopf. 1971. Harvest index in cereals. Agron. J. 63:224-226.
Watson, D.J., C.M. Thorne, and S.A.W. French. 1958. Physiological causes of differences in grain yield between varieties of barley. Ann. Bot. 22:321-352.
Watson, D.J., C.M. Thorne, and S.A.W. French. 1963. Analysis of growth and yield of winter and spring wheats. Ann. Bot. 27:1-22.
