Abstract: The F2∶6 upland-island RIL population of upland cotton (Zhong 07) and island cotton (Xinhai 20) was used as the materials, and was treated by a field drought-stress method at the blossom and boll stage. After the measurement of photosynthetic traits, the drought resistance of upland-island RIL population was evaluated through the methods of variance analysis, principal component analysis, cluster analysis and integrated drought assessment system. The results showed that the response degree of each indicator was different in different cotton materials under drought stress at blossom and boll stage, among which, the A, E and WUE showed significant changes. Through D value clustering analysis, the cotton materials were divided into four groups, 21 materials in group Ⅰ with strong drought resistance type, 7 materials in group Ⅱ with drought resistance type, 26 materials in group Ⅲ with drought sensitive type and 16 materials in group Ⅳ with extreme drought sensitive type. Through cluster analysis, the cotton materials of more drought-resistant lines than that of Zhong 07 and more drought-sensitive lines than that of Xinhai 20 were obtained.

Key words: cotton, upland-island RIL population, blossom and boll stage, photosynthetic characteristics, drought resistance evaluation