With CO2 concentration enrichment, the leafstoma density becomes small for C3 crops, but it shows the opposite tendency for C4 crops (maize).
随着CO2浓度升高，C3作物叶片气孔密度变小，C4作物（玉米）呈相反趋势；
2
The best regression models (e. g. Ulmus pumila) of leaf content against air SO2 and leaf stomatic resistance could explain that the sulfur acted as pollutant entered plant mainly through stoma.
植物叶片硫含量与大气SO2和气孔阻力的回归模型说明，以污染状态进入植物体的硫，主要通过气孔进入；
3
The mechanism of stoma and the differences of the correspondence of photosynthesis and transpiration to environmental changes were the physiological basis of WUE at leaf level.