Genetic Insights into Heterosis and Inbreeding Effects on Yield and Quality Attributes in Cotton (Gossypium hirsutum L.)

Background Information: Cotton (Gossypium hirsutum L.) is an economically important fiber crop, also valued for its seed, which serves as a source of oil and protein. Genetic enhancement of complex traits such as seed cotton yield, fiber quality and oil content remain primary objective in cotton breeding programs. The exploitation of heterosis offers a potential avenue for improving these traits through the development of superior F₁ hybrids. Conversely, inbreeding depression resulting from successive selfing leads to a decline in trait performance due to increased homozygosity and expression of deleterious alleles. Assessing the magnitude and direction of heterosis and inbreeding depression provides critical insights into the genetic architecture of target traits and aids in formulating effective selection strategies for the development of high-performing genotypes. Methodology: The present investigation carried out at Regional Cotton Research Station, Navsari Agricultural University, Bharuch during kharif 2023-24 with a view to estimate heterosis and inbreeding depression by adopting generation mean analysis. The experimental materials were consisting of four different crosses of cotton viz., GBHV 276 × GBHV 278, GBHV 276 × GN Cot32, G. Cot 16 BG II × GBHV 281 and BC-68-2 BG II × GBHV 217to estimate genetic parameters on various five characters viz., seed cotton yield per plant (g), fibre length (mm), fibre fineness (mv), fibre strength (g/tex) and oil content (%). Results: Highly significant and positive relative heterosis as well as heterobeltiosis were recorded in majority of the crosses for most of the characters. For the seed cotton yield per plant, the best heterotic cross was the cross III [G. Cot 16 BG II × GBHV 281] which also showed significant heterosis and heterobeltiosis in the desired direction for fibre length, fibre fineness, fibre strength and oil content. Hence, heterosis breeding in this cross i.e., cross III [G. Cot 16 BG II × GBHV 281] would be a more practical approach for getting higher seed cotton yield. With respect to the inbreeding depression, significant inbreeding depression was observed for majority of crosses for most of the characters included in present investigation.