德夯岩溶河谷异质生境中半蒴苣苔的水分生理生态适应性  

Water eco-physiological adaptability of Hemiboea subcapitata in heterogeneous habitats in the Dehang karst valley

作　　者：王晨瑶 张婷 曾德武 李龙 叶庆子 田向荣[1,2,4] WANG Chenyao;ZHANG Ting;ZENG Dewu;LI Long;YE Qingzi;TIAN Xiangrong(College of Biology and Environmental Sciences,Jishou University,Jishou,Hunan 416000,China;Key Laboratory of Plant Resources Conservation and Utilization in Colleges and Universities of Hunan Province,Jishou,Hunan 416000,China;Xiangxi UNESCO Global Geopark,Jishou,Hunan 416000,China;National&Local United Engineering Laboratory of Integrative Utilization Technology of Eucommia Ulmoides,Jishou,Hunan 416000,China)

机构地区：[1]吉首大学生物资源与环境科学学院,湖南吉首416000 [2]武陵山区植物资源保护与利用湖南省高校重点实验室,湖南吉首416000 [3]湘西世界地质公园,湖南吉首416000 [4]杜仲综合利用技术国家地方联合工程实验室,湖南吉首416000

出　　处：《中国岩溶》2024年第4期900-910,共11页Carsologica Sinica

基　　金：国家自然科学基金项目(31660119)。

摘　　要：以湘西世界地质公园德夯岩溶河谷内克隆植物半蒴苣苔(Hemiboea subcapitata)为材料,测定其生长、形态与光合水分生理指标,探究其对德夯岩溶台地河谷演化中形成的三类异质生境(峡谷岩壁表面、风化碎裂岩表和河岸有机质层)的水分生理生态适应性。结果显示:(1)异质生境中半蒴苣苔单(分)株叶片自然含水量仅有较小差异(<2%),而相对含水量和自然饱和亏则无显著差异;异质生境中叶片水分需求随基质含水量降低而明显增加,但叶片水势也随之显著降低。(2)单株生长差异大但群体累积生物量无明显差异。如峡谷岩壁表面单株的株高和叶面积均显著高于河岸有机质层单株,但群体累积株高、累积叶面积差异不显著。(3)单株外部形态变化显著,匍匐茎长度、直径和根着生密度均呈现峡谷岩壁表面>风化碎裂岩表>河岸有机质层的趋势;峡谷岩壁表面单株叶片比河岸有机质层单株平均增厚近60μm,比叶面积则降低至其78.2%,气孔密度则显著降低至其66%。(4)光合生理指标中,叶片气孔限制值随叶片水势降低而显著增加,同时气孔导度明显提升,故而胞间CO_(2)浓度并无明显变化,但峡谷岩壁表面单株叶片的净光合速率仅达到河岸有机质层单株叶片的69.6%。(5)水分亏缺最多的峡谷岩壁表面单株叶片水分利用效率却最低(3.029±0.461μmol CO_(2)·mmol^(-1)H_(2)O),仅为河岸有机质层单株的73%。表明,半蒴苣苔可通过自身水分维持机制来保证岩溶异质生境中单株水分的相对稳定,并以增加根系密度、匍匐茎长度、叶片厚度和重量,减少气孔密度等形态可塑性来适应干旱的岩溶岩壁生境,通过增加气孔导度保持蒸腾拉力来维持胞间CO_(2)浓度,以高耗水来维持生长状态相对稳定的方式达成对岩溶河谷水分异质性生境的适应。The Dehang canyon of Xiangxi UNESCO Global Geopark is cut by the runoff of streams.As a unique karst landform,it is an ideal area for studying plant species diversity and ecological adaptability.Collecting the clone plants,Hemiboea subcapitata,as samples from the Dehang karst valley in Xiangxi Global Geopark,this study measured their growth,morphology,and photosynthetic and water physiological indicators.On this basis,this study explored the water eco-physiological adaptability of the plants to three types of heterogeneous habitats formed during the evolution of the Dehang karst valley.These three habitats are canyon karst walls slightly weathering after water erosion without soil covering,bank weathered rocks with little soil covering and bank soil organic horizons highly weathering with soil covering.The results show as follows.(1)There was only a small difference(<2%)in the natural water content in ramet leaves of H.subcapitata in heterogeneous habitats,while there is no significant difference in terms of relative water content and natural saturation deficit.It is proved that they not only have a strong water maintenance mechanism but also have no obvious difference in their recovery ability after drought.The lowest water potential of canyon karst walls was-1.630±0.047 Mpa,and the highest water potential of bank soil organic horizons was−0.705±0.025 Mpa.It is obvious that,in heterogeneous habitats,the water demand of ramet leaves increased significantly with the decrease of the matrix water content,but the water potential of leaves decreased significantly.(2)There was a significant difference in ramet growth but no significant difference in total biomass.For example,the plant heights and leaf areas of ramets on the surfaces of canyon karst walls were significantly higher than those in bank soil organic horizons,but there was no significant difference in the cumulative height and leaf area of total population.(3)The morphological changes of ramets were significant.Values of lengths,diameters and root densit

关 键 词：岩溶河谷 半蒴苣苔 水分利用效率 水分生理生态适应 

分 类 号：Q948[生物学—植物学]