COMBINING ABILITY ANALYSIS IN DIALLEL CROSS OF UPLAND COTTON

Combining Ability (GCA and SCA) was studied in 6 × 6 F1 diallel crosses of upland cotton during 2009 at Sindh Agriculture University, Tandojam, Pakistan. The breeding material consisted of six Gossypium hirsutum genotypes viz: CRIS-134, CRIS-342, Sindh-1, NIAB-78, Sadori and BH-160 and their F1 diallel hybrids. Highly significant differences were observed among genotypes for all the variables. General combining ability (GCA) mean squares were highly significant for plant height, sympodia plant-1 and seedcotton yield plant-1 implying the importance of additive gene effects but non-significant for bolls plant-1, boll weight, ginning outturn and staple length. Specific combining ability (SCA) mean squares were highly significant for all the parameters prioritizing hybrid combinations in selection based on their SCA values. Regarding GCA estimates, cultivar CRIS-342 showed positive and highest estimates for all the parameters followed by CRIS-134 which manifested positive estimates also for all the parameters except ginning outturn and staple length. Other four cultivars revealed negative GCA effects for almost all the characters. The highest positive SCA effects were recorded for hybrid CRIS-134 × Sindh-1 and its reciprocal. The SCA estimates in the hybrid combinations were almost higher than their respective reciprocal crosses. Cultivars CRIS-134 and CRIS-342 were found good general combiners due to maximum GCA estimates, hence could further be utilized in future breeding program aimed at improving the studied parameters.