Estimation of Heterosis, Inbreeding Depression and Combining Ability by Using Diallel Analysis in F1 and F2 Generations for Some Quantitative Traits in Egyptian Cotton

Abstract

Plant breeders are seeking for desired genes and gene combinations, therefore identifying prospective individuals is critical in any breeding program. In this trend, this study was conducted at Sakha Agricultural Research Station, Cotton Research Institute, Egypt, during three growing seasons (2021 to 2023). Six Egyptian cotton varieties were used, using diallel analysis in F1 and F2 generations.
Genotypes, parents, crosses, and parents vs. crosses mean squares were extremely significant for all the studied characters in both generations, except for uniformity index in F2 generation for parents versus crosses. Giza 86 and Giza 94 exhibited significant desirable GCA effects for most yield traits in both generations, while Giza 92 and Giza 96 for most fiber quality traits in both generations. The crosses (Giza 96 x Giza 97) followed by (Giza 86 x Giza 92) were significant and positive (desirable) SCA effects for most yield and fiber quality properties in both generations. The cross combinations (Giza 85 x Giza 86), (Giza 85 x Giza 92), (Giza 85 x Giza 94), (Giza 85 x Giza 96), (Giza 86 x Giza 96), (Giza 94 x Giza 96) and (Giza 96 x Giza 97) demonstrated the best heterosis over mid and better parents for
most studied traits in F1. The results indicated that the additive genetic variance was higher as compared with non-additive genetic variance in both F1 and F2 for B/P, SCY/P, LCY/P and PI in both F1 and F2, indicating that additive effects play a major role in the expression of these traits.