Estimation of Heterosis and Combining Ability for Yield and Fibre Related Traits in Gossypium hirsutum L.

The combining ability and heterosis analysis are the important biological phenomenon that has been used to select the top performing parents and hybrids in different crop plants. In cotton, heterosis of morphological and yield related traits using line × tester design is very important to identify best performing parents in future cotton breeding program. Therefore, in this study five lines (MNH-1020, MNH-1035, FH-152, CIM-632 and BS-20) were crossed with three testers (CEMB-100, RH-662 and NIAB-5) using line × tester crossing design, which resulted 15 F1 hybrids. The analysis of variance found significant variation between the parents and hybrids, demonstrating the presence of genetic diversity. For several traits including plant height, number of nodes per plant, number of bolls, boll weight, yield per plant, percentage of ginning outturn (GOT%), fiber length, micronaire value and fiber strength, the ratio of general combining ability (GCA) variance to specific combining ability (SCA) variance (2 GCA/2 SCA) indicated the prevalence of non-additive gene action. In addition, lines FH-152, CIM-632 and BS-20 showed a strong GCA impact for majority of the studied traits. Significant GCA effects were seen among the testers for most of the qualities in NIAB-5. Further, the hybrids FH-152 × NIAB-5 and CIM-632 × NIAB-5 displayed strong SCA effects, positive heterosis, and heterobeltosis for different important traits.