Combining Ability in a Few Varieties of T. Aestivum, T. Compactum and T. Sphaerococcum

Combining ability studies were undertaken for ten quantitative characters in a diaUel set involving nine parents from three groups of hexaploid wheats T. aestirum, T. compactum and T. sphaerococcum. The gca and sca variances indicated that additive gene action was of greater importance for spike length, spike density, grain wt. per spike, 100-grain weight, and yield/plant; while for days to first flowering, plant height, number of tillers/plant, spikelets/spike, and grains/spike nonadditive component was more important. Dwarf or semidwarf parents, in general, were not good combiners for yield and also for the important yield components that emphatically indicated the consideration of height along with yield components in the selection criteria. Use of the hitherto unexploited semidwarfs like T. compactum and T. sphnaerococcum as the source of semidwarfing stiff straw gene(s) has been suggested. The per se performance of the parent is an adequate measure of gca for most characters except days to first flowering, tillers/plants, spikelets/spike, and grains/spike. It is also suggested that the crosses with at least one parent with superior gca effect will hesten genetic recombination and also help in overcoming the genetic barriers, if present.