Reciprocal Effect and Inbreeding Depression in Advanced Generations of Cotton (Gossypium hirsutum L.) Bulk Population

Reciprocal differences reflect an unequal contribution of male and female parents in plant breeding. We investigated the reciprocal differences, inbreeding depression, and performance of bulk populations in advanced generations. Seven hybrid combinations and their reciprocals were evaluated in F4 and F5 generations in a Randomized Complete Block Design with three replications. The significant reciprocal differences in many combinations for seed cotton yield and fiber length in both generations indicated the importance of selecting parents as male or female at the start of breeding work for these traits. In contrast, fiber fineness, fiber strength, and ginning out-turn were generally traits for which the reciprocal differences of the lines were not significant. The difference in general averages of F4 and F5 generations was significant regarding fiber length and fineness. Advanced lines in the F5 generation were found to have longer and finer fibers. In F4 generation lines, seed cotton yield per plant ranged between 100.30-160.87 g; ginning out-turn 41.96-47.17%; fiber length 30.04-32.94 mm; fiber fineness 4.52-5.11 mic. and fiber strength 32. 50-34.60 g tex-1, while these values were 101.11-137.63 g; 41.45-46.54%; 30.55-33.09 mm; 4.24-4.90 mic. and 32.03-34.30 g tex-1 in F5 generation, respectively. The higher inbreeding depression estimates for seed cotton yield indicated that non-additive genes were more predominant in the inheritance of this trait compared to ginning out-turn and fiber quality parameters. As a result of the study, it was concluded that it would be beneficial to transfer Carmen × Carisma, Flash × Claudia, and ST-468 × Claudia F5 advanced lines, which showed superior performance in terms of seed cotton yield and fiber properties, to the F6 generation.