Assessment of genetic variability and selection potential in F₂ segregating populations of upland cotton (Gossypium hirsutum L.)<b></b>

Knowledge of the magnitude of genetic and phenotypic variability present in a crop species is fundamental to designing effective breeding programmes for developing superior cultivars. In this study, eight F₂ segregating populations of upland cotton (Gossypium hirsutum L.) was (IUB-2013 × NIA-95, Chandi-95 × M-23, NIA-Ufaq × M-35, NIAB-878 × Chandi-95, NIA-Noori × IUB-2013, Sadori × M-32, Sohni × NIA-Ufaq, ZAD-1 × Sadori) along with their twelve  respective parents (IUB-2013, NIA-95, Chandi-95, M-23, NIA-Ufaq, M-35, NIAB-878, NIA-Noori, Sadori, M-32, Sohni, ZAD-1), generated from selected intra-specific crosses, were evaluated together with their twelve parental genotypes at the experimental field of the Nuclear Institute of Agriculture (NIA), Tandojam, during the 2025 Kharif season, using a randomized complete block design with three replications. Analysis of variance detected significant differences among genotypes for plant height, sympodial branches plant⁻¹, bolls plant⁻¹, boll weight, seed cotton yield plant⁻¹, ginning outturn percentage, staple length and micronaire, confirming that exploitable genetic variability was present in the breeding material. Among the parents, NIA-Ufaq combined the tallest plant stature, the greatest number of bolls plant⁻¹ and the highest seed cotton yield plant⁻¹, while the F₂ crosses NIAB-878 × Chandi-95 and NIA-Noori × IUB-2013 recorded the highest seed cotton yield among the segregating populations. Broad-sense heritability estimates varied widely across traits and crosses, ranging from 3.66% (ginning outturn, Chandi-95 × M-23) to 99.17% (boll weight, Chandi-95 × M-23), while genetic advance ranged from 0.05 to 70.53 depending on the trait and cross combination considered. Seed cotton yield plant⁻¹ combined moderate-to-high heritability with substantial genetic advance in several crosses, most notably Chandi-95 × M-23 and NIA-Ufaq × M-35, indicating predominance of additive gene action and good scope for direct phenotypic selection in early generations. The crosses Chandi-95 × M-23, NIA-Ufaq × M-35, NIAB-878 × Chandi-95 and NIA-Noori × IUB-2013 displayed transgressive segregation for seed cotton yield, exceeding both respective parents, and are recommended as promising material for pedigree breeding aimed at developing high-yielding upland cotton genotypes.