Combining Ability for Yield Characters in Upland Cotton

An 8 X 8 diallel analysis of combining ability for seven yield characters in Gossypium hirsutum was conducted with the aim to obtain information on the genetic architecture of the population and also to isolate best parents for hybridization. Though the estimates of both the combining ability (general and specific) variances were significant for all the seven characters studied, the magnitude of the general combining ability variances were 2 to 4 times higher than the specific combining ability variance, indicating thereby the importance of both additive and dominance genetic variances, former being more prevalent. The per se performance of the parents was not usually associated with their combining ability effects. A 102 was the best general combiner for yield, boll weight and sympod number, while L.S.S. was for boll number and monopod number. The best combiners for loculi per boll and short stature were H 14 and SA 594, respectively. The cross combinations of the overall best two parents, i.e. A 102 X L.S.S. was the best combination for most of the seven characters studied. The best commercial varieties of the tract were not the best combiners, thus suggesting that it may not always be desirable to reserve a place for the local variety in hybridization programmes unless they are found to be better combiners.