Comparison Of Phytohormone Content And Agronomic Characteristics Between Parents And Its Hybrids In Cotton

The new breeding method and technology is the most important and active research area of modern breeding, and breeders all over the world are trying to find better method so as to create new varieties quickly and effectively. In order to provide the theoretic basis for using phytohormone regulation to improve cotton fibre quality and to guide cotton breeding, the differences of IAA, GA₃, ABA and Z in seedling root system and leaf between cotton parent and its hybrids were compared, and the correlationship between the content of phytohormones and the fibre quality as well as photosynthesis and yield characteristics was discussed in the paper through the messurement and analysis of phytohormones in cotton parent and its hybrids. The main results are as follows.1. The contents of IAA and GA₃ in F1 seedling leaves have distinct heterobeltiosis. The content of ABA between F1 and its parents was at the same level but no fixed relationship of Z was found between F1 and its parents. It is suggested that the heterosis of F1 during the early development stage is correlated with IAA and GA₃.2. Both IAA and GA₃ in F1 seedling leaves were very high but the difference of IAA content between F1 and its parents was far more than that of GA₃ in our experiment, indicating that IAA is more important than GA₃ in the process of heterosis formation of cotton.3. Our results showed that the content of Z at seedling stage of cotton was significantly correlated with photosynthetic characteristics at 0.01 level. Moreover, in cotton varieties with high Z content, the growth period was longer and the chlorophyll content was higher than that of the varieties with low Z content, and the photosynthetic rate, Stomatal conductance, transpiration rate and photosynthetically active radiation as well were also better than that of the varieties with low Z content. 4. In our experiment, the fibre fineness, biological output, potosynthesis characteristics and the contents of GA₃ and IAA as well in seedling root system and leaf of N1 and N7 were better than that of the others. The conventional lint percentage of seed cotton, however, was lower than that of the others. The contents of GA₃ and IAA was found to be tighly correlated with the fibre trait and plant growth and development , indicating that GA₃ and IAA in leaves have important effects on the fibre trait and cotton output.