Fractional Diallel Analysis of Some Quality Characters in Bread Wheat

Combining ability analyses were done for specific gravity, protein, lysine and tryptophan contents of the grain in Triticum aestivum.

Substantial differences were observed among parents and hybrids for specific gravity, protein and lysine contents. The varieties differed significantly for tryptophan content in flour. Heterosis was negligible for all the quality characteristics studied. Increase in the protein content of the grain resulted in a corresponding decrease in lysine. Similarly, tryptophan in protein was negatively correlated with crude protein content in the hybrids but not in parents. However, such relationships were essentially non-linear.

Predominantly non-additive gene action was indicated for specific gravity and protein content of the grain although the additive component was substantial. Both additive and non-additive gene action appeared to be equally important in the inheritance of lysine. Heritability estimates were fairly high for protein content and specific gravity of the grain. Analysis of generation means for specific gravity showed the preponderance of dominance and interaction effects with pronounced duplicate epistasis. The studies indicated the feasibility of achieving simultaneous improvement for specific gravity, protein quantity and quality of the grain.