不同光合类型牧草对干旱-复水的光合生理响应及生长适应策略  

Photosynthetic physiology and growth adaptation of herbages with different photosynthetic pathways in response to drought-rehydration

作　　者：李斐 孙明伟 钟尚志 宋文政 钟晓月 孙伟[1] LI Fei;SUN Ming-Wei;ZHONG Shang-Zhi;SONG Wen-Zheng;ZHONG Xiao-Yue;SUN Wei(Key Laboratory for Vegetation Ecology,Ministry of Education,Institute of Grassland Science,Northeast Normal University,Changchun 130024,China)

机构地区：[1]东北师范大学草地科学研究所,植被生态科学教育部重点实验室,长春130024

出　　处：《植物生态学报》2022年第1期74-87,共14页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金(31570470和31870456)。

摘　　要：基于干旱频率增加、强度增大这一全球降水变化背景,探究干旱-复水条件下不同功能群(C_(3)和C_(4))植物的光合生理响应及生长适应策略有助于预测降水格局变化条件下草地的植被组成和生态系统功能。该研究采用盆栽实验,以松嫩草地生长的一年生C_(3)(4种)和C_(4)(3种)牧草为实验材料,设置了对照、中度干旱和重度干旱3个水分处理水平,在干旱末期及复水期对植物进行气体交换、生物量和比叶质量的测量。在干旱条件下,各物种净光合速率和气孔导度均呈下降趋势,水分利用效率呈上升趋势。干旱对不同植物光合指标的影响存在功能群差异,随干旱程度的增加C_(4)植物逐渐丧失光合优势,重度干旱对C_(4)植物净光合速率的影响较C_(3)植物更加明显。由于干旱条件下C_(3)植物光合固碳主要受气孔限制而C_(4)植物主要受代谢限制,因此复水后C_(4)植物净光合速率恢复速度较C_(3)植物慢。干旱条件下,各物种的生物量降低,根冠比和比叶质量升高,干旱对C_(3)植物各生长指标的影响均大于C_(4)植物;复水处理后,C_(3)植物生物量随干旱强度增加呈下降趋势,而C_(4)植物的生物量与对照相比无显著差异。Aims Based on the background of increasing drought frequency and intensity globally,investigating the photo-synthetic properties and growth adaptation of annual grasses differed in photosynthetic pathway(C_(3) and C_(4))in response to drought-rehydration conditions is useful to predict the changes of grassland ecosystem composition,structure and function in the context of global climate change.Methods The study was conducted as a pot experiment with four annual C_(3) and three C_(4) grasses widely grown in the Songnen Grassland.Three water levels were set up including control,moderate drought and severe drought.Plant photosynthetic(leaf gas exchange)and growth(biomass,leaf mass per area etc.)parameters were measured at the end of the drought and during the rehydration periods.Important findings The net photosynthetic rate(A)and stomatal conductance(Gs)of all studied species showed a decreasing trend and water use efficiency showed an increasing trend under the drought conditions.There were functional group differences in the effects of drought on photosynthetic properties of the studied plants.The effects of the severe drought on net photosynthetic rate of the C_(4) plants are more pronounced than that of the C_(3) plants,with the C_(4) plants gradually losing their photosynthetic advantage as drought severity increases.The A of the C_(4) plants recovered more slowly than that of the C_(3) plants after the rehydration because of carbon assimilation in the C_(3) plants was mainly restricted by stomata limitation while it in the C_(4) plants was mainly restricted by metabolic limitation.The biomass of all studied species decreased,but the root to shoot ratio and leaf mass per area increased,under the drought conditions.The effects of drought on all growth indicators were greater in the C_(3) plants than in the C_(4) plants.After the rehydration,the biomass of C_(3) plants showed a decreasing trend with increasing drought intensity,while the biomass of C_(4) plants was not significantly different from the control tr

关 键 词：干旱 复水 功能群 光合限制 根冠比 

分 类 号：S54[农业科学—作物学]