COMBINING ABILITY ANALYSIS IN INTRA SPECIFIC F-1 DIALLEL CROSS OF UPLAND COTTON

The research work comprised of combining ability and genetic variability in a 6 x 6 F-1 diallel cross carried out during 2008 and 2009 at the University of Agriculture, Peshawar, Pakistan. The parental upland cotton genotypes were CIM446, CIM-496, CIM-499, CIM-506, CIM-554 and CIM-707. Significant (P= 0.01) differences were observed among genotypes for days to first flowering, locules boll-1, seeds locule-1, lint% and seed cotton yield plant-1. The F-1 hybrids showed significant increase over parents in mean values for all the traits. Mean squares due to general (GCA) and specific combining ability (SCA) were highly significant for all the traits, except locules for GCA. The GCA mean squares were higher than SCA for majority of the traits revealed that additive type genes governed their inheritance. The best general combiners (CIM-446 and CIM-554) followed by CIM-496 and their utilization as one of the parents produced best specific F-1 hybrids (CIM-446 x CIM-499, CIM-446 x CIM-554, CIM-496 x CIM-707 and CIM-506 x CIM-554) having valuable SCA determination and remarkable mean performance for most of the traits. Correlation of yield was significantly positive with majority of yield traits and negative with days to first flowering and lint%. The promising F-1 hybrids exhibited earliness, and could be used for selection in early segregating generations, and some specific F-1 hybrids can be used for hybrid cotton production. However, the combined performance of F-1 and F-2 hybrids could be a good indicator to identify the most promising populations.