EFFECT OF PROVENANCE AND CLIMATE ON XYLEM ANATOMY OF HALOXYLON AMMODENDRON (C. A. MEY) BUNGE IN THE GURBANTUNGGUT DESERT, CHINA

Although Haloxylon ammodendron is widely distributed in desert regions of both Asia and Africa, the anatomical structure of its xylem is rarely reported.In this study, the differences in xylem anatomical characteristics among five provenances in the southern Gurbantunggut Desert were compared and the effects of climatic factors on anatomical features were analyzed.The results showed that the xylem responded to low precipitation by increasing ray density and ray height to improve the storage of water and starch to combat drought stress.In an arid provenance (Jinghe), H. ammodendron had wide vessels to improve conductivity.Moreover, they increased the vessel wall thickness to decrease its sensitivity to embolism.Both average temperature in January and maximum wind velocity from April to June were significantly related to the wall thickness of the fiber (P ＜ 0.05), indicating that a thicker fiber cell wall could provide higher mechanical resistance to steady stems and improve vessel conduction in low temperature and strong wind conditions.These results indicate that there is high plasticity in the xylem anatomical structures of H. ammodendron in response to different desert conditions and also explain the adaptation of the plant to a wide range of Asian and African deserts.