Combining ability of rice genotypes under coastal saline soils

Six lines and five testers were crossed in line x tester fashion and the F1s were evaluated under coastal saline situation. The ratio between the estimates of additive and dominance variances indicated preponderance of nonadditive gene action for the characters namely, plant height, number of productive tillers, boot leaf length, panicle length, grain weight per primary panicle and grain yield per plant. Among the parents, IR 65847-3B-6-2 recorded significantly superior grain yield per plant and panicle length. Parent IR 65192-4B-8-1 recorded superior mean for boot leaf length, panicle length and grain weight per panicle. Among the lines IR 65847-3B- 6-2 and IR 65192-4B-8-1 showed good combining ability for grain yield per plant, panicle length and grain weight per panicle. It indicates the existence of good relationship between per se performance and gca effects of parents. Among the hybrids, IR 65847-3B-6-2 X Vandana, IR 65847-3B-6-2 X ADT 45, IR 65847-3B-6-2 X Norungan, IR 65847-3B-6-2 x MDU 5, IR 65847-3B-6-2 X PMK 2, IR 65192-4B-8-1 X Vandana, IR 65192- 4B-8-1 X ADT 45, IR 65192-4B-8-1 X Norungan, IR 65192-4B-8-1 X MDU 5 and IR 65192-4B-8-1 X PMK 2 recorded significantly superior grain yield per plant and grain weight per primary panicle. With regard to specific combining ability effects, all these hybrids recorded additive gene action except IR 65847-3B-6-2 X ADT 45. The hybrids IR 65847-3B-6-2 X ADT 45 recorded non additive gene action especially of dominance X dominance type. Hence these crosses can be subjected to pedigree breeding to evolve high yielding genotypes suitable for coastal saline soils.