Combining Ability Analysis of Heat Tolerance in Gossypium hirsutum L.

Abstract

In order to study the genetic control of heat tolerance, four varieties/lines of Gossypium hirsutum L., namely MNH-554, Cocker-304, Delcerro and Albacala (71) 1190, were crossed in all possible combinations. Heat tolerance of 12 hybrids and their parents was measured at reproductive phase using an electrolyte leakage technique. The genetic analysis of the data showed significant effects of specific combining ability and reciprocals, but the effect of general combining ability appeared to be non-significant. Comparison of the parents for heat tolerance revealed that Delcerro and MNH-554 were the best general combiners for the character. The crosses Cocker-304 × Delcerro and Albacala (71) 1190 × MNH-554 were determined as the best combinations for heat tolerance and they involved one good general combiner as a parent. Significant effects due to specific combining ability indicated the importance of non-additive gene effects controlling heat tolerance. This information suggests that development of heat tolerance in the present plant material may be difficult; therefore it is necessary to design a specific breeding programme for efficient transfer of the trait.

Keywords

• combining ability
• genetic basis
• gossypium hirsutum
• heat tolerance
• membrane thermal stability