Combining ability, heterosis and stability for yield and fibre quality traits in cotton: Breeding approaches and future prospects

Cotton breeding has progressed significantly with the integration of conventional and molecular approaches aimed at enhancing yield, fiber quality, and adaptability to biotic and abiotic stresses. In order to create superior cotton hybrids, heterosis, or hybrid vigor, is essential. Both intraspecific and interspecific crossings exhibit notable improvements in component characteristics and seed cotton production. Finding prospective parental lines and cross combinations requires evaluating both general combining ability (GCA) and specialized combining ability (SCA). While SCA denotes non-additive gene effects, namely dominance and epistasis, which contribute to heterotic performance in particular crossings, GCA represents additive gene effects, which are frequently associated with the accumulation of advantageous alleles across generations. Heterosis exploitation is widely used in cotton hybrid breeding projects to evaluate GCA and SCA through top-cross, line × tester, and systematic diallel studies. The accuracy of detecting high GCA parents and better SCA hybrids has increased because to developments in genomic selection, marker-assisted selection, and biotechnological treatments. In order to maximize heterosis expression, increase genetic variety, and maintain production in the face of climatic unpredictability, future opportunities lay in combining genomic methods with traditional breeding. The next stage of cotton enhancement may be fueled by a smart mix of utilizing molecular breakthroughs, optimizing combining ability, and taking use of heterosis.