半干旱区典型沙生植物油蒿(Artemisia ordosica)的光合特性  

Photosynthetic characteristics of typical desert plant Artemisia ordosica in semi-arid region

作　　者：李媛[1,2] 查天山[1,2] 贾昕[1,2] 秦树高[1,2] 吴雅娟[1,2] 王奔[1,2] 

机构地区：[1]北京林业大学水土保持学院,宁夏盐池毛乌素沙地生态系统国家定位观测研究站,北京100083 [2]北京林业大学水土保持国家林业局重点实验室,北京100083

出　　处：《生态学杂志》2015年第1期86-93,共8页Chinese Journal of Ecology

基　　金：国家自然科学基金项目(31270755和31200537)资助

摘　　要：为了研究西北半干旱生态系统中典型沙生植物油蒿（Artemisia ordosica）的光合特征,于2012年5—10月,使用Li-6400（Li-Cor Inc.,USA）便携式光合测定系统,测定了油蒿气体交换特征的日变化、季节变化以及净光合速率（Pn）对光合有效辐射和胞间CO2浓度的响应。结果表明：Pn、蒸腾速率（E）和水分利用效率（WUE）的日变化在12：00前后均表现出非对称性,上午测量值普遍高于下午;Pn日均值6月最高（8.97±1.73μmol CO2·m-2·s-1）,10月最低（2.58±1.32μmol CO2·m-2·s-1）;油蒿表观量子效率（α）在0.022-0.048 mol·mol-1变化,羧化效率（φ）在0.125-0.268 mol·m-2·s-1变化;在9月13日饱和光强下的Pn（Pnmax）达到生长季最大值,为24.89μmol CO2·m-2·s-1;在7月31日饱和胞间CO2浓度下的Pn（Anmax）,达到生长季最大值,为77.23μmol CO2·m-2·s-1;Pnmax主要受到相对湿度影响,Anmax主要受饱和水汽压亏缺和30 cm深度土壤体积含水率影响;水分相关环境因子是油蒿光合作用的主要限制因子,其光合特征反映出对半干旱气候的适应性。本研究结果可为生态系统过程建模和区域尺度研究提供重要的生理生态参数。Using a portable photosynthesis system, we measured the leaf gas exchange character- istics of Artemisia ordosica, a dominant shrub species in semi-arid areas of Northwest China, from May to October 2012 to quantify the temporal variations and environmental controls of its photo- synthetic characteristics. Results showed that the diurnal variations of net photosynthesis rate （Pn）, transpiration rate （E） and water use efficiency （WUE） were all asymmetric around 12：00, being higher in the morning than in the afternoon. Daily mean Pn varied over the growing season, being highest in June [ （8.97±1.73） μmol CO2·m-2·s-1] and lowest in October [ （2.58±1.32） μmol CO2·m-2·s-1]. The apparent quantum yield （a） and the carboxylation efficiency （φ） of A. ordosica varied in the range 0.022-0.048 mol· mol-1 and 0.125-0.268 molμmol ·m-2·s-1, respectively. The maximum net photosynthetic rate at the optimum light intensity （Pnmax） and saturation intercellular CO2 concentration （A ） occurred on 13 September （24.89 μmol CO2·m-2·s-1） and 31 July （77.23 μmol CO2·m-2·s-1）, respectively. The P was significantly correlated with the atmospheric relative humidity, and A was significant- ly correlated with vapor pressure deficit and soil volumetric water content at 30 cm depth. Our re-sults indicated that the carbon assimilation of A. ordosica was primarily limited by moisture related factors, and the photosynthetic characteristics of A. ordosica reflected its adaptation to semi-arid conditions with low water availability and high summer temperature. In addition, our study pro- vides important eco-physiological parameters that may help develop process-based ecosystem car- bon-cycle models.

关 键 词：油蒿 光合 日变化 季节变化 响应曲线 

分 类 号：Q945.11[生物学—植物学]