中文摘要：

通过对生长在塔克拉玛干沙漠南缘极端干旱区野外生境条件下的4种多年生植物胡杨、柽柳、沙拐枣和骆驼刺的主要水分关系参数（P100为膨压最大时的渗透势;P0为膨压为零时的渗透势;emax为最大细胞弹性模量;RWCa为细胞在质壁分离点时的相对含水量）在植物生长周期内的变化特征进行了分析,结合对植物清晨水势和土壤含水率变化的系统进行测定。结果表明：4种植物在低水势下保持膨压能力大小的排序为柽柳〉胡杨〉骆驼刺〉沙拐枣。4种植物应对水分胁迫的共同反应是在细胞出现质壁分离时,保持高的体内含水量;在耐旱机理上,沙拐枣和骆驼刺属于高水势延迟脱水类型,胡杨和柽柳属于低水势忍耐脱水类型;在植物生长期内,4种植物清晨水势的变化特征是,骆驼刺的清晨水势值最高,沙拐枣和胡杨的清晨水势值的季节变化较为稳定,柽柳的清晨水势值最低;植物清晨水势的变化趋势同其水分关系参数的变化特性基本一致;4种植物没有受到严重的水分胁迫,灌溉对植物水分关系参数变化的影响不显著;植物处并利用地下水来满足其生存和生长需求,维持地下水位的基本稳定,是保证多年生植物恢复重建的重要前提。

英文摘要：

With four perennial plant species （Populus euphratica Oliv.,Tamarix ramosissima Ledeb.,Calligonum caput-medusae Schrenk. and Alhagi sparsifolia Shap.） in the southern fringe of Takelamakan Desert as test objects,the variation characteristics of their main water relation parameters P100 （osmotic potential at maximum turgor）,P0 （osmotic potential at zero turgor）,emax （maximum cell elasticity modulus）,and RWCa （cell relative water content at incipient plasmolysis） in growth period were analyzed based on pressure-volume curves （P-V curves）. In the meantime,the predawn water potential of test species was measured,and the soil water content was monitored. As for the ability of maintaining turgor at low water potential,it was in order of T. ramosissima〉P. euphratica〉A. sparsifolia〉C. caput-medusae. The common response of the four species to water stress was to keep relatively high water content when incipient plasmolysis occurred. As for the mechanisms of drought-endurance,C. caput-medusae and A. sparsifolia belonged to the type of keeping high water potential to delay dehydration,while P. euphratica and T. ramosissima belonged to the type of keeping low water potential to endure dehydration. Among the four species,A. sparsifolia had the highest predawn water potential,while T. ramosissima had the lowest one. C. caput-medusae and P. euphratica had a stable predawn water potential during its growth period. The variation tendency of predawn water potential was consistent with the change characteristics of water relation parameters of the species. No signs of serious drought stress were observed in any of the test species during their growth period. Irrigation had no significant effects on the water relation parameters of test species,suggesting that the four perennial plant species were well adapted to the harsh environmental condition. The root systems of the species could access groundwater to satisfy their large demands for water. To protect the root systems of the species and to maintain