荒漠植物白刺光合作用对人工模拟增雨的响应与适应

Response and acclimation of photosynthesis in Nitraria tangutorum to rain addition treatments in temperate desert in Northwest China

研究未来降水增加条件下荒漠植物白刺光合作用对人工模拟增雨的响应和适应。实验共设置5个处理,包括对照、自然降水基础上分别增加年平均降水量(145 mm)的25%、50%、75%和100%。对2010年生长季白刺叶片光合速率、叶周气温、清晨叶水势、土壤含水量等监测指标进行分析。研究结果表明:白刺叶片净光合速率与叶周气温之间呈二次函数关系,人工增雨处理后拟合曲线顶点左右平移。与对照相比,25%和50%增雨处理样地的拟合曲线顶点左移,顶点对应的叶周气温较对照样地(29.31℃)分别降低0.44和0.74℃;75%和100%增雨处理样地的拟合曲线大幅度右移,顶点对应的叶周气温较对照样地分别升高2.26和6.02℃左右。人工模拟增雨改变了白刺光合作用对温度的适应范围。

In this study, a field manipulative experiment was conducted with five simulated rain amount treatments （control, natural rain plus 25% , 50% , 75% , and 100% of multi-year mean precipitation） in a desert ecosystem in Northwest China, where the carbon cycle is extremely sensitive to the changes of rainfall amount and pattern. Photosynthesis and its temperature dependence in a desert shrub Nitraria tangutorum were investigated. The results are showed as follows. Rain addition treatments changed the magnitude of the photosynthetic acclimation to temperature in N. tangutorum. The apexes of the quadratic curves between photosynthesis rate and leaf surface air temperature shifted from about 29.31℃ in control plots to 28.87℃ and 28.57 ℃, in plots with 25% and 50% rain addition treatments, respectively. However, the apexes of the quadratic curves between photosynthesis rate and leaf surface air temperature shifted to 31.57 ℃and 35.33 % in plots with 75% and 100% rain addition treatments, respectively. The results will deepen our understanding of desert system carbon cycle.