Generation mean analysis based estimation of heritability and genetic advance for yield, fibre quality and oil content in cotton (Gossypium hirsutum L.)

The present investigation elucidated the genetic basis of seed cotton yield and its component traits in Gossypium hirsutum L. through the estimation of narrow-sense heritability (h²ns) and expected genetic advance as a percentage of mean (GA%). Four diverse crosses viz., GBHV 276 × GBHV 278, GBHV 276 × GN Cot 32, G. Cot 16 BG II × GBHV 281, and BC-68-2 BG II × GBHV 217 were evaluated in six generations (P₁, P₂, F₁, F₂, BC₁, and BC₂) during Kharif 2023-24 at the Regional Cotton Research Station, Navsari Agricultural University, Bharuch, Gujarat, India. Data were recorded on 13 yield, yield-attributing, and fibre quality traits including days to 50% flowering, plant height, monopodia, sympodia, bolls per plant, boll weight, seed cotton yield, lint yield, ginning percentage, seed index, fibre length, fibre strength, fibre fineness and oil content. Narrow-sense heritability estimates ranged from 22.45% (boll weight) to 78.62% (seed cotton yield per plant), while GA% varied from 8.94% (days to 50% flowering) to 45.31% (seed cotton yield per plant). High h²ns coupled with high GA% was consistently recorded for monopodia, sympodia, bolls per plant, boll weight, lint yield per plant, seed index, fibre fineness and oil content across several crosses, suggesting the predominance of additive gene action and greater scope for improvement through direct selection. Traits such as bolls per plant and seed cotton yield per plant exhibited moderate h²ns with high GA%, implying additive gene effects influenced by environmental factors, whereas fibre length and fibre strength displayed high h²ns but low GA%, indicating non-additive gene action where heterosis breeding would be advantageous. Among the four crosses, G. Cot 16 BG II × GBHV 281 and BC-68-2 BG II × GBHV 217 emerged as promising parental combinations for simultaneous improvement of yield and fibre quality traits. The findings highlight the potential of early-generation selection for high-heritability traits and recurrent selection strategies for traits governed by non-additive gene action, providing valuable insights for cotton improvement programmes.