中文摘要：

【目的】探讨东北山樱幼苗对水分胁迫的响应机制，为评价其资源特性提供理论和实践依据。【方法】采用持续干旱和淹水处理，测定根系呼吸途径和相关酶活性、呼吸底物、叶片叶绿素荧光参数等指标的变化过程，比较分析东北山樱幼苗对不同程度水分胁迫响应特征的差异及形成机制。【结果】持续干旱和淹水胁迫对东北山樱幼苗根系呼吸等生理代谢造成严重影响。干旱胁迫1d后根系活力即受到严重抑制，而淹水胁迫在3d后表现为迅速降低；干旱胁迫后根系呼吸速率先升高，第5天时达到峰值后迅速降低，而淹水胁迫前5d无明显变化，之后也迅速降低。水分胁迫1d时根系呼吸各生化途径和电子传递途径比例未发生明显变化，而后三羧酸循环（TCA）、细胞色素途径（CP）比例迅速降低，磷酸戊糖途径（PPP）和交替途径（AP）成为主要方式，第7天后各途径所占比例均大幅降低，根系呼吸代谢被严重抑制；轻度干旱和淹水胁迫使根系中琥珀酸脱氢酶（SDH）等TCA关键酶活性降低，而诱导葡萄糖一6一磷酸脱氢酶（G-6-PDH）等PPP关键酶活性的表达；胁迫第7天后超过幼苗耐受阈值，各关键酶活性大幅降低，严重削弱了其酶促调控作用；根系中的呼吸底物可溶性糖、淀粉及呼吸代谢中间产物丙酮酸的含量在水分胁迫期间均表现为先上升后迅速降低，而柠檬酸含量持续下降；持续干旱和淹水胁迫也造成叶片最大光化学效率（Fv／Fm）降低，光合作用受到抑制，植物干物质积累量明显下降。【结论】水分胁迫初期东北山樱幼苗通过调节SDH等呼吸关键酶活性、改变PPP、AP等呼吸途径比例的方式，调整呼吸底物的消耗及呼吸代谢中间产物的形成，以适应不良外界环境，且幼苗对淹水胁迫的响应滞后于干旱胁迫。持续干旱与淹水胁迫对幼苗根系呼吸、叶片光

英文摘要：

[ Objective ] The mechanisms of Cerasus sachalinensis Kom. seedlings responding to water stress were studied in order to provide a academic and practical basis for evaluating the resource characteristics. [ Method] Changes of root respiratory pathways, related enzyme activities, respiratory substrates and chlorophyll fluorescence parameters of leaves were determined using continual drought and waterlogging treatments. Different mechanisms of C. sachalinensis Kom. seedlings responding to water stress in different extents were compared and analyzed. [Result] Seedling growth and respiratory metabolism were both badly influenced by continuous drought and waterlogging stresses. Root activities were badly restrained after 1-day drought, but rapidly depressed after 3-day waterlogging. The roots respiratory rates under drought stress were firstly increased then rapidly dropped, and the peak value appeared at 5 d. However, the respiratory rates hardly changed at the first five days of waterlogging and then decreased. The root biochemical respiratory pathways and electron transfer pathways were not changed significantly under 1-day water stress, and then the percentages of TCA and CP dropped sharply, PPP and AP became the leading way. After 7-day water stress, the proportions of each pathway were all decreased greatly. Root respiratory metabolisms were badly checked. The key enzyme activities of TCA pathway such as SDH were reduced whereas the key enzyme activities of PPP pathway such as G-6-PDH were induced under drought and waterlogging stress in some extent. Tolerance to drought and waterlogging of seedlings stretched to the limit after 7 days of treatment. Each key enzyme activity and the regulation were greatly declined. The respiratory substrate contents such as soluble sucrose and starch and the respiratory intermediate products pyruvic acid were firstly increased and then rapidly dropped during the water stress. However, the citric acid contents were continually decreased. Moreover, continual drought and waterloggi