Abstract: To elucidate the heterosis mechanism of high-yield hybrid cotton varieties Gang 0996 and Gangzamian 10, experiments were conducted using these two hybrids and their parental lines. By comparing their differences in yield traits, agronomic traits, fiber quality, and related traits of subtending leaves of cotton bolls with their parents, the heterosis was systematically evaluated. Combined with correlation analysis, the main morphological factors affecting high yield in hybrid cotton were explored. The results showed that the heterosis rates of total subtending leaf area, subtending leaf area of opened bolls, and average boll leaf area of Gangzamian 10 reached 12.14%, 9.74%, and 9.42%, respectively, with an over-parent heterosis rate of 3.19% for total subtending leaf area. During the whole cotton boll development stage, the relative chlorophyll content (SPAD value) in subtending leaves of cotton bolls of the two hybrids remained at a high level continuously. In terms of yield, the heterosis rates of seed cotton yield for Gang 0996 and Gangzamian 10 were 19.50% and 19.99%, respectively, with over-parent heterosis rates both exceeding 17%, and the heterosis rates of lint yield were 19.52% and 24.76%, respectively. For fiber quality, the heterosis rate of breaking strength of Gangzamian 10 was 9.00%, with an over-parent heterosis rate of 6.60%. Coefficient of variation analysis indicated that the two hybrids exhibited relatively large variations in traits such as total subtending leaf area, lint yield, and seed cotton yield. Correlation analysis demonstrated that seed cotton yield was significantly positively correlated with single boll weight and fiber uniformity index, and extremely significantly negatively correlated with growth period. This study revealed that the two high-yield hybrid cotton varieties achieved high yield and superior quality through the synergistic advantages of optimized leaf area, photosynthetic performance, yield components, and fiber quality.

Key words: high-yield hybrid cotton, Gang 0996, Gangzamian 10, heterosis, agronomic traits, yield traits, fiber quality, correlation analysis