1a生草本植物沙米(Agriophyllum squarrosum)是西北干旱区植被恢复建设的重要经济草本,目前干旱胁迫程度对于沙米叶片功能性状的影响并未完全厘清,一定程度上限制了沙米的应用场景和生态用途。以沙米为研究对象,设置4个水分梯度的盆栽控水实验(即CK,LD,MD,ED。其处理分别为田间持水量的90%±5%,70%±5%,50%±5%,30%±5%),探究沙米上下层叶片的结构性状与光合色素含量对干旱胁迫程度的响应特征。结果表明:1)随着干旱胁迫程度增加,沙米叶片的比叶面积(SLA)、叶片相对含水量(LRWC)、总叶绿素含量(Chl)及叶绿素a(Chl a)含量均显著降低,但轻度干旱处理(LD处理)时差异不显著;2)尽管叶片组织密度(LTD)、干物质含量(LDMC)随干旱胁迫程度增加而逐渐增加,但各处理间的差异并未达到显著水平;3)叶绿素b含量(Chl b)在干旱作用下仅发生了轻微降低,类胡萝卜素含量(Car)在各干旱处理间的变化较小;4)4种水分处理下,沙米叶片SLA和LRWC在叶位上存在显著差异,即上层叶片SLA高于下层叶片12.34%,上层叶片LRWC低于下层叶片4.37%。干旱胁迫与叶位对沙米叶片LRWC存在显著的交互作用。因此,在选择沙米进行大规模植被恢复时,叶片相对含水量可以作为衡量沙米个体适应土壤水分变化的重要生理指标。

The annual herb Agriophyllum squarrosum is an important economic herb for vegetation restoration and construction in the arid area of Northwest China. At present,the impact of drought stress on the functional properties of its leaves has not been fully clarified,which limits the application scenario and ecological use of it to a certain extent. Taking A.squarrosum as the research object,this paper set up four pot water control experiments with water gradients (CK,LD,MD and ED treatments were 90% ± 5%,70%±5%,50%±5% and 30%±5% of the field water capacity respectively),to explore the response characteristics of structural characters of upper and lower leaves and photosynthetic pigment content of A.squarrosum to different degrees of drought stress. The results showed that:1) the response of leaf traits of A.squarrosum at different leaf positions to drought was basically the same. With the increase of drought stress,the specific leaf area (SLA),leaf relative water content (LRWC),total chlorophyll content (Chl) and chlorophyll a content of A.squarrosum leaves decreased significantly,but the time difference of light drought treatment (LD treatment) was not significant. 2) Although the leaf tissue density (LTD) and dry matter content (LDMC) increased gradually with the degree of drought stress,the difference among the treatments did not reach a significant level. 3) The content of chlorophyll b (Chl b) decreased only slightly under drought,and the content of carotenoid (Car) changed little among drought treatments. 4)Under the four water treatments,there were significant differences in leaf position between SLA and LRWC of A.squarrosum leaves,the SLA of upper leaves was 12.34% higher than that of lower leaves,and its LRWC was 4.37% lower than that of lower leaves. There was a significant interaction between drought stress and leaf position on LRWC in A.squarrosum leaves. Therefore,when selecting A.squarrosum for large-scale vegetation restoration,the relative water content of leaves can be used as an important physiological index to measure the individual adaptation of A.squarrosum to soil water changes. The results can provide a theoretical reference for vegetation restoration and sustainable ecological management of forest and grass in sandy areas.