不同土壤湿度下柠条光合速率对CO_2浓度和辐射强度响应的模拟研究

Impacts of CO_2 Concentration and Radiant Intensity on C. intermedia Photosynthetic Rate Under Different Soil Moisture with a Simulation Condition

在控制土壤湿度水平下,模拟大气中CO2浓度升高和辐射增强对柠条光合作用的影响。结果表明,在CO2浓度饱和点以下,柠条的光合速率对CO2浓度的响应表现为线性关系,对辐射的响应表现为对数函数关系。柠条光合速率随辐射强度增加和/或CO2浓度的升高而增大。在土壤湿度较大时,柠条光合速率的变化率随辐射强度的增大而增大;在土壤湿度较小时,光合速率在辐射强度为500μmol·m-·2s-1时对CO2浓度的响应最敏感。柠条的暗呼吸随CO2浓度的升高而增大,土壤湿度越小,柠条的暗呼吸对CO2浓度的响应越敏感。

CO2 in the atmosphere is an essential substance for plant photosynthesis, and solar radiation is a vital energy for plant photosynthesis. Recently, CO2 concentration in atmosphere is increasing by human activities, which results in changes in temperature, water and radiation. Studying impact of changes in CO2 concentration, soil water, radiation and other eco-environmental factors on plants has been regarded as one of the foci in global change studies. C. intermedia is one of the dominant shrubs in Mu Us sandland of China. The present study on response of C. intermedia photosynthetic rate to CO2 concentration and radiation change may provide a basis understanding for human in intervention to renew and expanding natural vegetation, conserving and improving eco-environment, in order to advance sustainable use of water resources and establish sand plant succession, renewal and sustainable development under global change. The experiment was conducted in a growth chambers. The plant C. intermedia was cultivated in pot with 3 treatments for soil water contents and 7 treatments for radiant intensities as well as 6 to 8 treatments for CO2 concentrations. Photosynthetic rate was measured by a Li-6400 portable photosynthesis system. The analysis shows that under constant radiation, the response of C. intermedia photosynthetic rate to CO2 concentration showed a linear function, and under constant CO2 concentration, the response to radiation showed a logarithm function, under different soil moistures. C. intermedia photosynthetic rate increased with radiant intensity and/or CO2 enrichment. Under higher soil moisture, the variety tendency of change ratio of photosynthetic rate was greater along with radiant intensity enhancement. However, under lower soil moisture, the response of C. intermedia photosynthetic rate to CO2 concentration change was most sensitivity in radiant intensity of 500 μmol·m^-2·s^-1. The dark respiration of C. intermedia showed increasing tendency along with CO2 concentration enrichment. The lower soil moisture, the more sensitivity for the response of C. intermedia dark respiration to CO2 concentration change was.