中文摘要：

对雅布赖风沙口固定沙丘（阳坡和阴坡）、丘间低地和对照（人工加水）4种生境中白刺的叶片水势（Ψs）、含水量（LWC）、净光合速率（Pn）、蒸腾速率（Tr）和气孔导度（Cs）等进行了对比研究.结果表明：各生境下白刺叶片白刺叶片渗透势值分别为-3.11MPa,-2.02MPa,-1.34MPa和-1.21MPa;白刺叶片水势随生境土壤水势（Ψsoil）升高而增加,变化趋势为：固定沙丘〈丘间低地〈对照（p〈0.01）.叶片含水量随生活型及生境的变化与渗透势相似,而叶片渗透势与含水量呈显著正相关（p〈0.01）,与气孔导度呈显著的指数关系（p〈0.01）.0～2500μmol·m-2·s-1光强范围内,白刺的净光合速率随土壤含水量的增大而增大,蒸腾速率随光强的增高不断增大.白刺叶片平均水分利用效率在丘间低地土壤含水量为6.9%时达到最大值,因此,白刺的光能利用效率和水分利用效率都比较好的土壤含水量应该为7%左右.

英文摘要：

In this paper,the leaf osmotic potential（Ψs）,leaf water content（LWC）,net photosynthesis rate（Pn）,transpiration rate（Tr）and stomatal conductance of Nitraria tangutorum leaves were investigated in the four main habitats of Yabrai sandstorm belt,i.e.,fixed sand dunes（south facing and north facing）,lowland and contrast point.The relationships between the leaf osmotic potential and leaf water content,as well as growth forms and habitats were also examined.The leaf osmotic potential value of Nitraria tangutorum leaves was -3.11 MPa,-2.02 MPa,-1.34 MPa and-1.21 MPa for the four main habitats.The leaf osmotic potential increased with the soil water potential,in the rank of fixed sand dune lowlandcontrast point.The leaf osmotic potential values of different growth forms were ordered as follows：the south facing slopes of fixed sand dunethe north facing slopes of fixed sand dune lowlandcontrast point（P0.01）.Moreover,leaf water contents similar to the leaf osmotic potential were recorded in the four main habitats.It is also found a positive correlation existing between the leaf osmotic potential and leaf water content（P0.001）and an exponential relationship between the leaf osmotic potential and stomatal conductance in all habitats（P0.01）.Within the range of 0～2 500μmol·m-2·s-1 of photosynthetic active radiation,net photosynthesis rate increased with soil water content,and transpiration rate increased with photosynthetic active radiation.In the light of the average net photosynthesis rate and the average water use efficiency,the soil water content,in which both the solar energy utilization efficiency and the water use efficiency of Nitraria tangutorumleaves are better,is about 8%.