边界层阻力在叶片气体交换过程中的作用

EFFECTS OF BOUNDARY LAYER CONDUCTANCE ON LEAF GAS EXCHANGE

作者对现有的气体交换法的叶室作了改进。从实验上检验了作者根据电学类比分析和模拟检验得到的结论：在已有的气体交换测定装置中，空气流速不变，叶片的边界层导度也固定不变，所得到的结论用于边界层导度变化的情形时，会造成比较大的误差。现加一障碍物使得流过叶片的风速减小，从而改变叶片的边界层导度。通过测量在不同边界层导度下同一叶片的光强曲线可以考察不同边界层导度下的气孔导度、光合速率、蒸腾速率以及它们之间的相互关系。

Using an improved gas exchange technique for leaf chamber the authors’ conclusions derived from electrical analogy analysis and simulation have been tested.In most devices for gas exchange measurements, a fixed ventilation speed is used, which results in a fixed boundary layer conductance of leaf, but the results of experiments are often used to predict canopy transpiration or photosynthesis where the boundary layer conductance changes with the position of the leaf in the canopy and the wind speed above the canopy.To change the boundary layer conductance of a leaf, a barrier of variable size was inserted into the leaf chamber to decrease the wind speed over the leaf.The responses of stomatal conductance, net photosynthetic rate, and transpiration rate to light were then measured.The relationships amongst them have been tested.The experimental results matched well with the results predicted by electrical analogy analysis and simulation in most cases.