Abstract: [Objective] This research investigated the effects of water stress, provenance and their interactions on leaf functional traits of Salix gordejevii, and explored the effect of climate on provenance differences. [Method] One-year-old S. gordejevii seedlings were collected from six locations, and water stress experiments on the six provenances were conducted at four levels: mild, moderate and severe waterstress, and the control. A Li-Cor6400 photosynthesis measurement system was used to determine the photosynthetic indexes. The climate data of six locations were extracted from the WorldCLIM global high resolution (1 km×1 km) climate database using ArcGis9.2, and mean annual precipitation (MAP) and mean annual temperature (MAT) were calculated using these climatic data. The response of leaf functional traits of six S. gordejevii provenances under different water stresses were analysed using analysis of variance (ANOVA). The effects of climate of origin, provenance and water stress on leaf function traits were examined using general linear model (GLM), and Pearson correlation was used to analyse the relationship between climate (MAT, MAP) and leaf functional traits. [Result] 1)net photosynthetic rate (P_n), transpiration rate (E), water use efficiency (WUE) and relative water content (RWC) of S. gordejevii were significantly affected by water stress. 2)Provenances had significant influence on all traits, but the strength differed among traits. For P_n and E, the effect of provenaces was weaker than water stress; For WUE and RWC, provenance mainly influenced their responses to water stress; SLA was mainly affected by provenaces but not water stress. 3)Provenance climate had a significant impact on the provenance differences of P_n, E and WUE, and provenance differences of P_n was led by climate and non-climatic factors of the seedling's origins. However, provenance differences of RWC and SLA were mainly caused by non-climatic factor. [Conclusion] There were significant differences for leaf functional traits of S. gordejevii among different provenances and under different water stress, but the influence strength of provenance and water stress on leaf functional traits was differented. Provenance climate could explain a part of the effect of provenance on leaf functional traits of S. gordejevii. However, there was remarkable difference in influence of provenance climate on different leaf functional traits. Therefore, the differences in leaf functional traits of S. gordejevii not only reflected the physiological and ecological responses of different provenances to different water stress, but also revealed to ecological adaptability of different provenances due to differences in geographical environment.

Key words: water stress, provenance, Salix gordejevii, climate of origin, leaf functional traits