Genetic Basis of Combining Ability for Various Quantitative Traits Using CMS Lines of Rice (Oryza sativa L.)

Line × Tester experiment was carried out at the Experimental Farm of Rice Research and Training Center (RRTC), Sakha, Kafrelsheikh, Egypt during three growing seasons to evaluate the performance of 21 F1 hybrids along with their parents. Three cytoplasmic male sterile lines, two wild abortive (Wild Abortive); IR69625A, IR70368A and one (Kalinga) K17A as female were tested with seven cultivars/lines as testers. The analysis of variance detected that, highly significant variations among genotypes (parental lines with their crosses) for all traits in both seasons and in their combined analysis. Two hybrid combinations; IR69625A×Giza178 and IR69625A×Giza179 were recorded the best values for grain yield under both seasons and their combined. General combining ability (GCA) and specific combining ability (SCA) effects of genotypes for the studied traits were estimated. The results indicated that, K17A (female) and Giza 179 (male) were the best combiner for early heading date and could be useful to breed early maturing rice cultivars. The CMS line IR69625A and Giza178, Giza179 gave highly significant and positive GCA value and so appeared to be good parental lines combiner in hybrid combinations for high grain yield/plant. The positive values of GCA mean increased for grain yield/plant, which could be useful in breeding programs for high yield potential rice cultivars. The hybrid combination IR69625A×Giza179 showed highly significant and positive SCA estimates under both seasons and their combined. In conclusion, it is clear that this hybrid seemed promising hybrid for earliness and high grain yield under Egyptian conditions.