红壤坡地农业景观（旱季）地表界面水分传输研究——Ⅱ．叶面冠层-大气界面水分传输

Study on surface water transport in agricultural landscape on the slop lands of red soil (dry season) Ⅱ . Water transport at leaf-atmosphere interface

定位观测红壤坡地典型作物系统叶面冠层-大气界面水分传输结果表明,叶面冠层-大气界面水汽传输通量大小取决于景观植物群落的构建,稳定群落叶面冠层-大气界面水汽传输通量有明显日变化规律,除受植物生理机制影响外,还明显受土壤水分和气象条件的影响.植株叶片蒸腾速率有明显日变化规律且呈单峰型曲线及多峰态势.净辐射、空气饱和水汽压差、气温、地表温度、风速对蒸腾的影响均达极显著水平(正相关),其中净辐射、气温为主要影响因子.叶片气孔导度可反映叶片蒸腾速率,叶片气孔阻力日变化规律是植物对气象条件的响应,且受土壤水分状况强烈影响.改善作物生长环境,调节气孔行为,进而协调作物蒸腾作用和光合作用耗水制约,可调控叶面冠层-大气界面水分传输,提高作物水分利用效率.

After observing the water transport at leaf-atmosphere interface of typical c rop system, it is proved that the water vapor transfer flux is determined by the construction of plant community. The variation of water vapor transfer flux at l eaf-atmosphere interface of a stable community is not only apparently affected by soil moisture and meteorological condition but also by plant physiological me chanism. Transpiration velocity has daily variation. The analysis show that the net radiation,saturated-air water vapor balance,air temperature,surface tempera ture and wind speed have highly significant influence on transpiration (positive correlation). The net radiation and air temperature are the main factors. Stoma tal conductivity of leaf reflects its transpiration velocity and the daily varia tion of stomatal resistance is the plant response to meteorological condition. S tomatal resistance is strongly affected by soil moisture. By improving growth co ndition of crop,adjusting stomatal action, harmonizing crop transpiration and wa ter-consuming restriction of photosynthesis,the water vapor transfer at leaf -atmosphere can be adjusted and controlled and the water use efficiency of crop can be increased.