Combining ability studies in GMS based diploid cotton with special reference to fibre quality traits

Combining ability analysis using line x tester design was conducted during 2009–10 between 18 lines and three testers to generate a total of 54 hybrids. The estimates of gca and sca variance components revealed that non-additive components were predominant for all the characters. The estimates of general combining ability effects indicated that lines GMS-2, Mi-GMS, GAK-09A, RGMS-2, SGMS-2, GAKA-423, 8401-GMS and GAK-15A and tester Jayadhar were the best general combiners for seed cotton yield per plant and some other yield contributing characters. The line RGMS-3 was the best general combiner for 2.5 per cent span length, fibre strength and micronaire value. There were seven cross combinations which were best specific combinations for seed cotton yield per plant. Among them, the cross GAKA-423 x H-221 had highest magnitude followed by GAK-09A × H-221 for seed cotton per plant. The crosses GMS-2 × H-221, GAK-09A × H-221, GAKA-423 × H-221 and RGMS-2 × DDhC-11 were best combinations for bolls per plant, boll weight and seed cotton yield per plant together. The cross GMS-7 × Jayadhar was best combination for fibre strength, whereas the crosses GMS-2 × Jayadhar and Hi-GMS × H-221 were found the best combinations for micronaire value. The cross combination GMS-4-1 × DDhC-11 was best when 2.5% span length, fibre strength and micronaire were considered together. The crosses, which showed highest significant positive sca effects for seed cotton yield, had cross combinations of high × high, high × low gca parents indicating genetic interaction of additive × additive, additive × dominance or dominance × dominance interactions.