干旱胁迫下新疆杨树冠不同高度叶片水分状况与非结构性碳动态北大核心CSCD

水力结构调整及非结构性碳动态对于认知干旱胁迫下植物生存前景和死亡风险至关重要。该研究以新疆杨(Populus bolleana Lauche.)为对象,通过干旱处理分析树冠不同高度叶片水力性状、光合生理特性、不同功能器官间的可溶性糖、淀粉及非结构性碳水化合物(NSC)含量变化,以甄别树冠不同高度叶片对干旱胁迫的生理响应和适应差异。结果表明:(1)在干旱胁迫下,树冠上部的叶水势、叶含水量、枝条含水量普遍低于下部,饱和膨压渗透势及膨压损失点水势在不同树冠高度间差异不显著;(2)干旱处理组植株净光合速率随树冠高度的增加而降低,叶绿素SPAD值在树冠的上部显著低于下部,而水分利用效率在树冠的上部却高于下部;(3)干旱处理组比叶面积在各树冠高度下显著低于对照组,而胡伯尔值在中部及上部高于对照组但差异不显著;(4)干旱处理组,树冠上部叶片淀粉含量显著高于下部,枝条可溶性糖及NSC含量在树冠上部显著高于下部,韧皮部的可溶性糖、淀粉及NSC含量在不同树冠高度间无显著差异,细根的可溶性糖、淀粉及NSC含量在对照组与干旱处理组间的差异不显著。研究发现,干旱处理下,树冠高度的增加会加剧新疆杨枝叶的干旱胁迫,致使树冠上部枝条木质部发生栓塞的风险大于下部,并导致NSC在不同器官间的分配和组分产生差异,但新疆杨植株可通过水分利用效率和形态上的适应性调整减缓干旱胁迫。

Leaf Water Status and Non structural Carbohydrate Dynamics with Different Crown Height Levels of Populus bolleana Lauche. under Drought Stress

Adjustment of hydraulic architecture and dynamic in non-structural carbohydrates are crucial for understanding the survival prospects and mortality risks of plants under drought stress. We used Populus bolleana Lauche. as the target species. By analyzing the changes of leaf hydraulic traits, photosynthetic physiological characteristics, non-structural carbohydrate (NSC) contents and their components under different water treatments with contrasting, crown heights, we explored the differences in physiological responses and adaptations of leaves at different height levels. The research showed that: (1) during June to August, for the drought treatment group, the leaf water potential, leaf water content and branch water content in the upper part of tree crown were generally lower than those in the lower part; the osmotic potential at full turgor and the water potential at turgor loss point were not significant differences among different crown heights; (2) under drought stress, the net photosynthetic rate decreased with the increase of crown height, the chlorophyll SPAD value was significantly lower in the upper part of the crown than in the lower part, while the water use efficiency was higher in the upper part of the crown than in the lower part; (3) the specific leaf area under drought treatment was significantly lower than that of the control at each crown height, while the Huber value in the middle and upper part was higher than that of the control, but the difference was not significant; (4) the starch content of leaves in upper crown was significantly higher than that in lower crown under drought treatment; the soluble sugar and NSC contents in the upper part of the tree crown were significantly higher than those in the lower part of the tree crown; the contents of soluble sugar, starch and NSC in phloem had no significant difference among different crown heights; the contents of soluble sugar, starch and NSC in fine roots had no significant difference among different water treatments. It was found that the increase in crown height under drought treatment exacerbated drought stress in P. bolleana branches and leaves, resulting in a greater risk of xylem embolism in the upper branches of the crown than in the lower, and led to differences in the distribution and components of NSC among different organs, while P. bolleana plants could mitigate drought stress through adjustments in water use efficiency and morphological adaptations.