Abstract: In order to reveal the response mechanism of growth and bark thickness for Eucalyptus urophylla under different water and fertilizer gradients, 31 clones treated with nine combination of water and nutrients were used as experimental materials. After 18 months of artificial control of water and nutrient, the height, ground diameter, height under branch, 1/4 diameter, 2/4 diameter, 3/4 diameter and bark thickness were measured. The co-efficient of variation, Duncan multiple comparison and principal components were analyzed, and excellent clones were selected. The results showed that the growth and bark thickness traits of E. urophylla clones had great variation. Among them, the variation coefficient of height under branch and ground diameter was 50.78% and 12.46%, respectively, which suggested that analyzed traits had extensive variation with rich genetic diversity. There were significant differences in height, ground diameter, bark thickness, 1/4 diameter, 2/4 diameter and 3/4 diameter of E. urophylla clones under different water and fertilizer treatments. All clones performed better under 32 and 33 treatments. The 6 traits could be integrated into 3 principal components, and the cumulative contribution rate of the first 3 principal components was 84%. According to the genotype values of height, bark thickness and ground diameter, the best clones were 30, 7, 1, 29, 20 and 6. The average genetic gain was increased by 10.73 cm, 0.02 mm and 0.83 mm, reaching 5.29%, 6.38% and 2.24%, respectively.

Key words: Eucalyptus urophylla, bark thickness, clone, growth traits

摘要： 以9种水肥处理的31个尾叶桉(Eucalyptus urophylla)无性系为试材，人工控制水肥18个月后对其树高、地径、枝下高、1/4树高直径、2/4树高直径、3/4树高直径和树皮厚性状指标进行测定，分析各性状的变异系数、Duncan多重比较和主成分，同时对优良无性系进行评选。结果显示，尾叶桉无性系生长性状存在较大变异，枝下高的变异系数最大，为50.78%，地径的变异系数最小，为12.46%，表明尾叶桉不同无性系间遗传多样性较丰富。尾叶桉无性系在不同水肥处理下苗木的树高、地径、树皮厚、1/4树高直径、2/4树高直径和3/4树高直径总体上差异显著，所有无性系在处理组合32、33下表现较优。6个性状可以综合为3个主成分，前3个主成分累计贡献率达84%。依据树高、树皮厚和地径的基因型值综合评选表现较好的无性系为30、7、1、29、20和6，平均遗传增益较整体水平分别提高10.73 cm、0.02 mm和0.83 mm，增幅达5.29%、6.38%和2.24%。

关键词: 尾叶桉, 树皮厚度, 无性系, 生长性状