Determination of General and Specific Combining Ability Effects in a Diallel Cross of Spring Wheat
Combining ability of some polygenic traits was studied in a set of 5 x 5 diallel cross involving five varieties of bread wheat viz., Inqalab 91, Uqab 2000, Punjab 96, MH. 97 and Fsd. 85. Mean squares for GCA effects were highly significant for fertile tillers per plant, spike length, spikelets per spike and grains per spike, significant for plant height and flag leaf area and non-significant for 1000-grain weight and grain yield per plant. Mean squares for SCA effects were highly significant for all the traits except fertile tillers per plant which was non-significant while reciprocal effects were non-significant for all the traits except spike length and grain yield per plant which were highly significant. The magnitude of GCA variance was higher than SCA variance for flag leaf area, fertile tillers per plant, spike length, spikelets per spike and grains per spike suggesting additive genetic control of these traits. Whereas, plant height, 1000-grain weight and grain yield per plant indicated the preponderance of non-additive genetic effects with higher magnitude of SCA variance. The varieties Uqab 2000 and Fsd. 85 were the best general combiners for most of the traits and could be used in further breeding programmes. Cross combinations Inqalab 91 x Fsd. 85, Uqab 2000 x MH. 97, Punjab 96 x MH. 97 and Uqab 2000 x Fsd. 85 with high SCA effects could be exploited for further selection of high yielding progenies.
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