The succeeding study sought to determine the mean performance of parental cultivars and heterotic effects in F₁ hybrids of upland cotton (Gossypium hirsutum L.). Six parental genotypes (Guliston, AN-Boyovut-2, Buxoro-102, Yuksalish, Shodlik-11, and Kelajak) underwent crossing to develop 30 complete diallel F₁ hybrids and evaluation in comparison with the standard cultivar (Guliston). The experiment layout in a randomized complete block design (RCBD) had three replications. Analysis of variance revealed significant differences among the parental genotypes and F₁ hybrids for most traits, except the staple length. The F₁ hybrids Guliston × AN-Boyovut-2 and AN-Boyovut-2 × Buxoro-102 produced the most bolls per plant, while the F₁ hybrids Guliston × Yuksalish, Guliston × AN-Boyovut-2, and Shodlik-11 × AN-Boyovut-2 showed the maximum boll weight. Parental genotype performance individually did not reliably predict the hybrid performance, indicating the complex genetic interactions in F₁ hybrids. The heterosis analysis showed the hybrids Guliston × AN-Boyovut-2 and AN-Boyovut-2 × Buxoro-102 exhibited relative heterosis exceeding 15%–20% and heterobeltiosis above 10%–15% for bolls per plant and boll weight, respectively. The considerable heterotic effects in the F₁ hybrids for bolls per plant and boll weight suggest that utilizing heterosis breeding could be effective.

Keywords: Upland cotton (G. hirsutum L.), hybrids, heterosis, heterobeltiosis, dominance, bolls per plant, boll weight, yield-related traits

Key findings: The upland cotton (G. hirsutum L.) hybrid Gulistan × AN-Boyovut-2 showed the best performance for boll weight and bolls per plant in the F₁ generation and proved to be the promising genotype for further improvement through breeding programs.