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Paper Details

Combining ability analysis over environments in diallel crosses in bread wheat (Triticum aestivum L.)


Journal Title:International Journal of Agricultural Sciences

Combining ability analysis was undertaken in a 12 x 12 half diallel progeny of bread wheat for grain yield and its component characters under timely (E1) and late sown (E2) conditions. The mean squares due to gca and sca showed highly significant differences for all the characters in both the environments, suggesting the importance of both additive and non-additive gene action. However, variances due to sca were higher in magnitude than gca for most of the traits except plant height and length of main spike in both the environments indicating the predominance of non-additive gene action. The low predictability ratios for most of the traits in both the sowing dates also confirm the results. However, the predictability ratios for plant height and length of main spike were near unity suggesting the importance of additive gene action in the inheritance of these characters. The estimates of gca effects of the parents revealed that GW 496 (in both the environments), GW 273, MACS 2496 and PBW 373 (in E1) while J 24 and HUW 234 (in E2) were observed to be good general combiners for grain yield and some contributing traits. The perusal of sca effects revealed that the crosses GW 496 x HD 2189, DL 788-2 x GW 173 and GW 496 x MACS 2496 were found to be good specific combiners with considerable per se performance in both the environments. The crosses GW 496 x PBW 373 in E1 and GW 496 x HD 2189 in E2 gave the highest sca effects as well as per se performance in respective generation. These crosses also showed desirable sca effects for the important yield contributing traits like number of tillers per plant, length of main spike, number of grains per plant, flag leaf area, biological yield per plant and harvest index. The crosses showing high sca effects for grain yield per plant involved high x high, high x low and low x low general combiners indicating the involvement of additive x additive, additive x dominance and dominance x dominance type of gene action in the inheritance of these characters. The simple pedigree selection in succeeding generations and non-conventional breeding methods like biparental mating coupled with few cycles of recurrent selection could be utilized for the exploitation of additive and non-additive gene action, respectively.