| 【Objective】The study was conducted to understand the effects of water and nutrient stresses on chlorophyll fluorescence characteristics of Eucalyptus urophylla clones.【Method】Chlorophyll fluorescence characteristics of 19 clones under water and nutrient stresses for 6 months were analyzed and evaluated by using a randomized complete block design based on two factors（water and nutrient）and three levels.【Result】Chlorophyll fluorescence parameters including Fo, Fm, ΦPS Ⅱ , qP, NPQ, ETR and Fv/Fm were significant different among these clones, indicating that different clones had different ability of light absorption and utilization under different water and nutrient treatments. After being treated for 6 months under water and nutrient stresses, the plant height, ground diameter and crown width were significant positively correlated with Fm, Fv/Fm, ΦPS Ⅱ and ETR, while leaf perimeter and leaf area were significant negatively correlated with Fo. The correlation coefficients between the same type traits were higher（the highest value was 0.99）, while the correlation coefficients between different types were also significant, but the correlation values were lower（the highest value was 0.21）. Twenty-six traits could be integrated into 4 principal components, and the cumulative contribution rate of the first four principal components was 93%, indicating that these traits were highly representative. Based on the shortest distance and the Euclidean distance cluster analysis, the 19 E. urophylla clones were divided into 4 groups.【Conclusion】The clone 5（LDUA10）and clone 10（LDUA24）were of good growth performance and high photosynthetic efficiency, which were recommended as excellent clones for application in practice. |
