灌溉条件下藏北紫花针茅光合特性及其对温度和CO_2浓度的短期响应  

Photosynthetic characteristics of Stipa purpurea under irrigation in northern Tibet and its short-term response to temperature and CO_2 concentration

作　　者：郭亚奇[1,2] 阿里穆斯[3,4] 高清竹[1,2] 段敏杰[1,2] 干珠扎布[1,2] 万运帆[1,2] 李玉娥[1,2] 郭红保 

机构地区：[1]中国农业科学院农业环境与可持续发展研究所,北京100081 [2]农业部农业环境与气候变化重点实验室,北京100081 [3]中央民族大学中国少数民族传统医学研究院,北京100081 [4]教育部中国少数民族传统医学重点实验室,北京100081 [5]西藏自治区那曲地区草原站,西藏那曲852100

出　　处：《植物生态学报》2011年第3期311-321,共11页Chinese Journal of Plant Ecology

基　　金：国家科技支撑计划项目(2007BAC03A06);国家自然科学基金(30800142;30800125和40775062);西藏那曲地区与中国农业科学院合作项目资助

摘　　要：利用LI-6400便携式光合作用测定仪,测定不同灌溉措施下紫花针茅(Stipa purpurea)的光合特性对CO2浓度和温度的响应,探讨了土壤水分、温度和CO2浓度升高对藏北高寒草地紫花针茅光合作用的影响。结果表明:1)紫花针茅各项光合特性参数对CO2浓度、温度和土壤水分的变化响应显著,并表现出明显的交互作用;2)CO2浓度升高促进光合速率,但CO2浓度过高时光合速率反而下降;温度升高抑制光合速率,土壤水分增加对高温条件下的光合作用具有补偿作用;土壤水分增加促进紫花针茅光合速率的升高;3)随着CO2浓度的升高,胞间CO2浓度逐渐增大,蒸腾速率降低,水分利用效率升高,气孔导度逐渐减小,且温度升高加剧气孔导度下降的程度。各光合参数在不同温度水平和土壤水分下表现不同:气孔导度在20℃时达到最大值,且土壤水分增加利于气孔导度的增大;温度上升抑制了胞间CO2浓度,且在土壤水分充足的条件下更显著;蒸腾速率随着温度的上升而加快,蒸腾速率与土壤水分的正相关关系明显;叶片饱和水汽压亏缺与温度成正比,充足的土壤水分会适当降低饱和水汽压亏缺;水分利用效率随着温度上升和土壤水分增多而减小。不同土壤水分条件下光合参数对温度的响应结果表明,土壤水分的增加对较高温度下光合及其生理参数与温度的关系具有一定的补偿作用。Aims Stipa purpurea is a dominant species of alpine grassland in northern Tibet, a region sensitive to climate change. Environmental variations in temperature, water and atmospheric carbon dioxide （CO2） concentration caused by regional climate change should affect the photosynthetic physiology of plants. Our objective was to investigate the response of S. purpurea to environmental variation. Methods We irrigated natural alpine grassland to imitate rainfall increasing soil moisture and then used a portable gas exchange system （LI-6400） to measure photosynthesis parameters at the irrigated field （H） and a natural field （CK）. During measurement, we set three levels of leaf temperature （15, 20 and 25 °C） and gradually elevated CO2 concentration from 50 to 1 500 μmol·mol–1. Important findings CO2, temperature and soil moisture affected photosynthesis parameters of S. purpurea significantly, and interactions were apparent among these three factors. Rising CO2 gradually increased net photosynthetic rate （Pn） until it decreased at extremely high CO2. Higher temperature caused Pn to decrease, but sufficient water supply partially alleviated the negative effect. Sufficient water supply increased Pn. With rising CO2, intercellular CO2 concentration （Ci） increased, transpiration rate （Tr） decreased, water use efficiency （WUE） increased and stomatal conductance （Gs） decreased; higher temperature caused Gs to decrease faster. The photosynthesis parameters abovewere also impacted by the combined actions of humidity and temperature. Gs was maximized at 20 °C, and sufficient water supply increased Gs further. Ci increased with increased temperature, and this response was more pronounced with sufficient water. Tr was positively correlated with temperature and soil water. Vapor pressure deficit （VPD） was directly proportional to temperature and decreased with sufficient water. Increased temperature and increased water supply made WUE decline. Therefore, increased soil water had comp

关 键 词：CO2浓度 光合作用 土壤水分 紫花针茅 温度 

分 类 号：Q945[生物学—植物学]