Evaluation and development of F۱ hybrids tolerant to Verticillium dahliae Klebhan

The present study focuses on evaluating cotton, Gossypium hirsutum L. varieties and their hybrids for resistance to Verticillium dahliae Kleb., one of the major pathogens causing wilt disease. Five varieties of different genetic origins—SB-۶, C-۶۵۴۱, Namangan-۳۴, C-۶۵۴۵, and Namangan-۷۷—were used as initial material for hybridization and further analyzed along with their F۱ and F۲ generations. Resistance was assessed by two complementary approaches: an enzyme-linked immunosorbent assay (ELISA) test system and a six-point field assessment method. Both methods provided consistent and comparable results, confirming their reliability for evaluating resistance to V. dahliae. The most resistant parental varieties were Namangan-۳۴, Namangan-۷۷, and C-۶۵۴۱. Among F۱ hybrids, high levels of resistance were observed in the combinations Namangan-۷۷ × C-۶۵۴۱, Namangan-۳۴ × SB-۶, C-۶۵۴۱ × SB-۶, C-۶۵۴۱ × C-۶۵۴۵, C-۶۵۴۵ × C-۶۵۴۱, and SB-۶ × C-۶۵۴۱. Analysis of the dominance index (hp) indicated adverse effects of both complete and incomplete dominance for susceptibility traits in several hybrid combinations, suggesting their potential use in breeding programs for developing resistant varieties. In the F۲ generation, combinations such as Namangan-۳۴ × C-۶۵۴۵, Namangan-۳۴ × SB-۶, C-۶۵۴۱ × Namangan-۷۷, and SB-۶ × Namangan-۷۷ exhibited lower mean susceptibility to V. dahliae. Variation series analysis also revealed individual plants with significantly greater resistance than either parent. Heritability coefficient (h²) analysis demonstrated genotypic variability ranging from weak to strong expression across hybrids. These findings highlight promising hybrid combinations and confirm the effectiveness of combined biochemical and field assessments for breeding cotton resistant to V. dahliae.

کلیدواژه ها:

Cotton ، Medium-fiber ، variety ، Hybrid ، Resistance ، Verticillium dahliae Kleb