Effects of Water Stress on Stay Green of Sugarcane Innovative Materials Yunge F_2 Generation

[Objective] This study aimed to investigate the effect of water stress on stay green of Yunge F2 generation. [Method] Total 26 sugarcane innovative germplasm materials of Yunge F2 generation, along with their female parent, were selected as the experimental materials. Based on the observation on appearance of stray green and other five physiological and biochemical indexes, the drought resis- tance of the experimental materials was evaluated comprehensively by subordinate function method, grey relational analysis, and cluster analysis. [Result] The rank of drought resistance of the experimental materials was not exactly the same between subordinate function method and grey relational analysis. However, the drought .re- sistance evaluation results by isometric range-based cluster analysis were consistent with those by the two foregoing methods except Yunge F2 11-68 and Yunge F1 11- 254. At the Euclidean distance of 2.00, the tested materials were classified into four groups. The first group included 8 drought-strongly resistant materials, the third group included 6 drought-moderately resistant materials, the fourth group included 3 drought-poorly resistant materials, and the second group included drought-strongly resistant and drought-moderately resistant materials. The drought resistance coeffi- cients of green leaf numberLtotal leaf number and top four leaves chlorophyll content showed significantly positive correlation with drought resistance comprehensive eval- uation value, thus green leaf number/total leaf number and top four leaves chloro- phyll content could be used as the evaluation indexes of drought resistance in sug- arcane. [Conclusion] The excellent materials possess strong drought resistance and good green holding performance, such as Yunge F2 11-159, can be used as crucial parents and basic germplasm materials in drought resistance breeding of sugarcane. 7