臭椿光合生理生态特性日变化研究

Studies on Eco-Physiological Characteristics of Photosynthetic of Diurnal Variation of Ailanthus altissima Swingle.

为了解臭椿光合生理生态特性及生长的适宜生态条件,培育出优质高产的森林,采用LI-6400便携式光合测定系统对臭椿的光合生理特性日变化及其与气象因子关系进行了研究。结果表明:臭椿的净光合速率日变化呈"双峰"型曲线,有明显的"午休"现象,第一个峰出现在10:00左右,第二个峰出现在14:00左右,日最大净光合速率为18.9μmol/(m2·s)。气孔导度的日变化呈"双峰"型曲线,蒸腾速率的日变化呈"单峰"型曲线,蒸腾速率在很大程度上决定于气孔的活动状态。叶片水压亏缺的峰值与光合有效辐射和大气温度的峰值在同一时间出现,胞间CO2浓度因为气孔导度的降低而减少,臭椿的光合速率控制因子为气孔限制。各环境因子主要对蒸腾速率、水压亏缺和叶面温度的作用而影响的净光合速率,光合有效辐射对光合特征参数的变化影响最大,且对净光合速率起决定性作用,其相关系数为0.543。

In order to understand the eco-physiological characteristics and its suitable ecological condition of Ailanthus altissima Swingle to develop high-quality and high-yield forest, the studies on diurnal change of photosynthetic characteristics of Ailanthus altissirna Swingle and its environmental factors were conducted with the Li-6400 portable photosynthetic system. The results showed as following： the diurnal change of net photosynthetic rate （Pn） presented a double-peak curve, which showed obvious midday depression. The first peak value occurred at 10：00 and the second one at 14：00, and the maximum of Pn was 18.9μmol/（m^2·s）; The diurnal change of stomatal conductance presented a double-peak curve too, while the transpiration rate （Tr） demonstrated a single-peak one, which was mainly determined to the stomatal status. The peak value of leaf water deficit, photosynthetic active radiation （PAR） and air temperature （Ta） appeared at the same time. Intercellular CO2 concentration （Ci） deceased with the dropping of stomatal conductance. The mainly controlling factor of photosynthetic rate of Ailanthus altissima Swingle displayed as stomatal limitation. The environmental factors affected the Pn mainly by affecting Tr, water deficit and Ta. The change of photosynthetic characteristic parameters was affected mostly by PAR, which was critical to Pn, and which correlation coefficient was 0.543.