干旱区植物叶片大小对叶表面蒸腾及叶温的影响

利用热及物质交换原理, 并结合前人研究成果, 在单叶尺度上建立了简单的叶温和水气蒸腾模型。模型通过预设值驱动, 预设值参照干旱区环境及植物叶片特征设置。模拟结果显示: 随气孔阻力的增加, 叶片蒸腾速率降低, 叶温升高; 同一环境下, 具有低辐射吸收率的叶片蒸腾速率和叶温更低, 并且气孔阻力越大, 这种差异越明显。另外, 叶片宽度及风速是影响叶片蒸腾及叶温的重要因子。干旱地区植物生长季节, 风速小于0.1 m·s ^-1、气孔阻力接近1000 s·m ^-1时, 降低叶片宽度不仅有利于降低叶片温度, 而且能够降低叶片蒸腾速率, 从而实现保持水分, 增强植物适应高温、干旱的能力。

Influence of leaf size of plant on leaf transpiration and temperature in arid regions

Aims Our objective was to demonstrate the influence of leaf size on leaf transpiration and temperature in arid regions.
Methods Based on energy and material exchange theory and the results of previous studies, we set up a single leaf energy and material exchange model combined with arid environmental conditions.
Important findings Leaf transpiration decreased with increasing stomatal resistance, but leaf temperature increased. Leaf transpiration and temperature decreased with decreasing leaf radiation absorption rate in the same environmental conditions. Moreover, leaf width and wind speed were important parameters in understanding leaf energy and material exchange. Leaf transpiration and temperature generally decreased with decreasing leaf width with wind speed <0.1 m·s ^-1 and stomatal resistance about 1000 s·m ^-1. Low leaf transpiration and temperature could encourage plant growth with the low water availability, high radiation and high temperature conditions in arid regions.