库布齐沙漠几种常见灌木光合生理特征与土壤含水量的关系

Relationship between photosynthetic physiological characteristics of several common shrub species and soil water content in Hobq Desert of Inner Mongolia,northern China

2006年7—9月,采用Licor-6400便携式光合作用测定系统在模拟光照条件下,对库布齐沙漠不同水分处理的3年生柽柳、小叶锦鸡儿、杨柴苗木进行观测。观测指标包括：光饱和点（LSP）、光补偿点（LCP）、表观量子效率（AQY）、净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）、胞间CO2浓度（Ci）、羧化效率（CE）等。运用SPSS数据处理软件进行分析,确定这3种灌木光合生理特征与土壤含水量之间的定量关系。结果表明：①3种灌木光合生理特征对土壤含水量变化具有明显的阈值响应。②不同土壤含水量（SWC）下,柽柳、小叶锦鸡儿、杨柴苗木Pn最大值（Pnmax）的增加幅度分别为5.21、6.48、14.31μmol/（m^2.s）。③LSP随土壤含水量（SWC）的变化并不是特别明显,值在1 000-1 400μmol/（m^2.s）之间波动。④LCP随SWC的增加呈下降趋势,变化范围为21.7-74.1μmol/（m^2.s）。⑤AQY随SWC的增加呈上升趋势,变化范围为0.01-0.04。⑥柽柳、小叶锦鸡儿和杨柴维持Pnmax的SWC分别为13.8%、13.3%和15.2%;维持最高叶片水分利用效率（WUE）的SWC分别为10.0%、11.0%和8.5%;土壤水合补偿点分别为1.1%、0.8%和0.9%。⑦柽柳、小叶锦鸡儿和杨柴最适宜的SWC范围分别为10.0%-13.8%、11.0%-13.3%和8.5%-15.2%。

The Licor-6400 portable photosynthesis system was used to measure photosynthetic physiological parameters of three-year-old ramosest tamarisk （Tamarix ramosissirna Ledeb. ）, small-leaved pea-shrub （Caragana microphylla Lam. ） and Mongolian sweet vetch （Hedysarum mongolicum Turcz. ） under different soil water content （SWC） and simulated photosynthetic conditions in Hobq Desert of Inner Mongolia, northern China from July to September in 2006. Measured variables included light saturation point （LSP）, light compensate point （LCP）, apparent quantum yield （AQY）, net photosynthetic rate （P,）, stomatal conductance （Gs）, transpiration rate （ Tr）, CO2 concentration （ Ci ） and carboxylation efficiency （ CE）. The SPSS software was used to develop the quantitative relations between photosynthetic physiological parameters and SWC. The results indicated that photosynthetic physiological parameters had a clear threshold-response to the variations of SWC. Under different SWC, the increasing extent of the maximum P. （P ） of T. a mosissima, C. microphylla and H. mongolicum was 5.21, 6.48 and 14.31 μmol/（m^2 .s）, respectively. Variations of LSP in different SWC were not apparent and varied from 1 000 to 1 400 μmol/（m2.s）. The LCP decreased with the increase of SWC and varied from 21.7 to 74.1 μmol/（m2.s）. The AQY increased with the increase of SWC and varied from 0.01 to 0.04. The optimum SWC to maintain P for T. amosissima, C. microphylla and H. mongolicum was 13.8%, 13.3% and 15.2%, respectively. The optimum SWC to achieve the maximum water use efficiency （WUE） of the three shrub species was 10.0%, 11.0% and 8.5 %, respectively. Soil water compensation point for hydration of the three shrub species was 1.1%, 0.8 % and 0.9%, respectively. It is concluded that the optimum SWC for T. amosissima, C. microphylla and H. mongolicum should be 10.0% - 13.8%, 11.0% - 13.3% and 8.5% - 15.2%, respectively.