Combining ability analysis over F1-F5 generations in diallel crosses of bread wheat
SummaryCombining ability studies for grain yield and its primary component traits in diallel crosses involving seven diverse wheat cultivars of bread wheat (Triticum aestivum L.) over generations F1-F5 are reported. The general and specific combining ability variances were significant in all generations for all the traits except specific combining ability variance for number of spikes per plant in the F5. The ratio of general to specific combining ability variances was significant for all the traits except grain yield in all the generations. This indicated an equal role of additive and non-additive gene effects in the inheritance of grain yield, and the predominance of the former for its component traits. The presence of significant specific combining ability variances in even the advanced generations may be the result of an additive x additive type of epistasis or evolutionary divergence among progenies in the same parental array. The relative breeding values of the parental varieties, as indicated by their general combining ability effects, did not vary much over the generations. The cheap and reliable procedure observed for making the choice of parents, selecting hybrids and predicting advanced generation (F5) bulk hybrid performance was the determination of breeding values of the parents on the relative performance of their F2 progeny bulks.
Comparison of graphic and combining ability analyses of diallel crosses in wheat.
The graphic and the combining ability analysis techniques of analysing diallel crosses were compared by using data obained from F1’s, F2’s and F3’s of all possible combinations of five varieties of wheat. The combining ability analysis was found to be better than the graphic analysis in predicting the prepotency of cultures. It was especially so in later generations when the expression of dominance effects is reduced. Graphic analysis gave consistant results in the presence of a high degree of dominance of alleles but failed to identify small but considerable proportions of non-allelic effects. When the degree of dominance was low, even small proportions of non-allelic effects were observed to confound the results. The graphic method was however, helpful in classifying the parents on the basis of allelic content.
Acetylation analysis of saccharides. 2. Microanalysis of neutral glycosphingolipids by means of acetylation with radioactive acetic anhydride.
Abstract The quantitative analysis of mixtures of glycosphingolipids by acetylation with radioactive acetic anhydride and separation by thin-layer chromatography is described. The method was primarily developed for screening of glycosphingolipid composition of tissues, cultured cells, and virus preparations. The sensitivity and linearity of the method is demonstrated. Although theoretically a much higher sensitivity is achievable, in practive about 10 −9 g of glycosphingolipid can be detected and tentatively identified. As an example, the acetylation pattern of lipids from a preparation of herpes simplex virus is demonstrated.