The performance of interspecific and intraspecific cotton hybrid populations were compared to investigate the correlation among F2, F3 and F4 bulk generations in terms of yield, lint percentage, and fiber quality during 2009 to 2011. In addition to that, this research investigated the effect of combining abilities on hybrid performance at further generations. For this purpose, nine interspecific and six intraspecific hybrids with eight parents were evaluated under west part of Turkey (Aegean region) environmental conditions. With the generation progresses, the highest drop in fiber length and fiber strength was detected in interspecific duo to the inbreeding depression and genetic breakdown in advanced populations. Based on 15 tested hybrids, the observed mean yield and fiber quality in the F2 does not adequately predict the performance of hybrids in the F4 generation. Thus, selection of individual plants should be delayed until the F4 generation especially for interspecific hybrids, but individual plants would be selected at early generation in intraspecific hybrid populations. In the study it was found that a higher general combining ability (GCA) does not necessarily confer a higher specific combining ability (SCA) and that the GCA and SCA were independent of one another, and that in F4 high yielded hybrid population was obtained from cross which at least one parent of hybrid has maximum positive GCA effects. These results show that instead of use only one criteria, F2 performance for intraspecific hybrids and F3 performance for interspecific hybrids, low heterosis and inbreeding depression, combining ability of parents could be used together to determine the most promising hybrid populations to be used as a source for further selection.

The performance of interspecific and intraspecific cotton hybrid populations were compared to investigate the correlation among the F2, F3 and F4 bulk generations in terms of yield, lint percentage, and fiber quality from 2009 to 2011. In addition, the effect of combining abilities on hybrid performance were investigated at further generations. For this purpose, nine interspecific and six intraspecific hybrids with eight parents were evaluated under the west part of Turkey (Aegean region) environmental conditions. With the generation progresses, the highest drops in fiber length and fiber strength were detected in interspecific due to the inbreeding depression and genetic breakdown in advanced populations. Based on 15 tested hybrids, the observed mean yield and fiber quality in the F2 do not adequately predict the performance of hybrids in the F4 generation. Thus, selection of individual plants should be delayed until the F4 generation especially for interspecific hybrids, but individual plants would be selected at early generation in intraspecific hybrid populations. In the study it was found that a higher general combining ability (GCA) does not necessarily confer a higher specific combining ability (SCA) and that the GCA and SCA were independent of one another, and that in F4 high yielded hybrid population was obtained from cross which at least one parent of hybrid has maximum positive GCA effects. These results indicated that instead of using only one criteria, the F2 performance for intraspecific hybrids and the F3 performance for interspecific hybrids, low heterosis and inbreeding depression, combining ability of parents could be used together to determine the most promising hybrid populations to be used as a source for further selection.