Abstract: Haloxylon ammodendron is a dominant desert species. A three-year experiment of precipitation treatments (100% reduction and control) was conducted in the southern margin of the Gurbantunggut Desert, Xinjiang, to examine the changes of stem hydraulic traits and physio-biochemical characteristics of H. ammodendron. Our results showed that drought did not affect water transport efficiency (specific hydraulic conductivity, leaf-specific hydraulic conductivity), embolism degree, and branch and leaf traits of H. ammodendron. Under drought stress, H. ammodendron maintained osmotic pressure and improved water holding capacity by increasing the contents of proline and soluble protein. Meanwhile, the content of malondialdehyde was kept at a low level by significantly increasing the activities of superoxide dismutase and catalase. The results of correlation analysis showed that stem specific hydraulic conductivity of H. ammodendron was significantly negatively correlated with embolism degree and positively correlated with specific leaf weight, while wood cross-sectional area was significantly positively correlated with leaf-specific hydraulic conductivity and embolism degree. It is concluded that H. ammodendron could resist drought stress and maintain normal physiological activities by increasing osmotic regulation ability and protective enzyme activity. High degree of natural embolism could also be a drought tolerant strategy of H. ammodendron in extreme arid habitats of desert areas.

Key words: