中文摘要：

基于控制试验研究了盐分（Na Cl）处理60 d对胡杨（Populus euphratica）幼苗生长和各器官矿质离子吸收、分布和运输的影响。结果表明：（1）盐分对幼苗生长有显著的抑制作用。与对照相比,轻度（50 mol·L^-1）、中度（100 mol·L^-1）和重度（200 mol·L^-1）盐分处理的幼苗株高生长速率、叶面积及各器官生物量分别减小了约30%、50%和80%。幼苗通过改变生物量分配策略,提高根冠比增加对资源的获取和减少体内水分散失,以增强其耐盐性。（2）盐分改变了幼苗对离子的选择性吸收和运输。与对照相比,各盐分处理显著提高了幼苗器官对Na^＋和Cl-的吸收,抑制了Ca^2＋、Mg^2＋和K^＋由根向茎、茎向叶选择性运输、降低了幼苗器官对Ca^2＋,K^＋,Mg^2＋的吸收,导致器官离子平衡遭到破坏。幼苗将较多的Na^＋积累在叶片,增大了地上和地下的渗透势差,这是胡杨幼苗抵御盐分胁迫的一个有效方式。（3）重度盐胁迫下幼苗增强对Ca^2＋、Mg^2＋和K^＋的选择性运输,避免高盐胁迫对幼苗更大的伤害。

英文摘要：

Populus euphratica, as the dominant species of the riparian forest along the Tarim River, northwest China, plays an important role in maintaining functions of the riparian ecosystem. Recent embankments along the river have altered the soil salinity condition due to water use by human or climate change, which is expected to influence regeneration of the riparian forest. To assess the potential effects of these alterations and elucidate the adaptation and endurance of P. euphratica seedlings to salinity stress, the paper examined growth performance, ionic distribution and transportation of P. euphratica seedlings across experimental soil salinity gradients.Results indicated that seedlings were limited in their growth performance, as evidenced by decreases height growth rates, leaf area and biomass across the salinity gradients. The height growth rate values in moderate （100 mol·L^-1） and severe （200 mol·L^-1） salinity stress achieved of approximately 50% and 20% respectively, in relation to control. In the same level of salt concentration, the order of ionic content in seedling was leaf 〉 root 〉 stem, leaf was the main part of ionic accumulation. Increasing salinity stress significantly elevated Na＋ content and Cl- content in root and shoot tissues （stem＋leaf） of P. euphratica seedlings, while K^＋, Ca^2＋ and Mg^2＋ contents showed reverse trends. Similar patterns as K^＋ content were also observed across soil salinity gradients in K^＋/Na^＋, Ca^2＋/Na^＋, Mg^2＋/Na^＋ ratio of root and shoot. The significant decrease of SK, Na, SCa, Na and SMg, Na of mild （50 mol·L^-1） and moderate （100 mol·L^-1） salinity stress, and the transport and absorption of nutrients were inhibited. Under severe （200 mol·L^-1） salinity stress condition, a marked drop of K＋ content in root and shoot tissues upon salt accumulation and a third of K^＋/Na^＋ ratio of seedlings those under control conditions suggests that decreasing osmotic pressure of seedling, and the seedlings suffered the