蒸腾速率、阻力与叶内外水势和光强关系的研究

Studies on Relations of Transpiration Rate and Stomatal Resistance with Leaf-air Water Potential and Light Intensity

本文采用ＬＩ一１６００稳态气孔计和压力室测定了杨柴的蒸腾速率、阻力、叶水势及其环境因子的日变化，分析结果表明：当０～２ｍ土层内土壤平均水势在－０．０４～－０．２０ＭＰａ时，光照强度是影响杨柴等树木蒸腾速率的主要因子，它主要是通过影响蒸腾阻力所致。光照强度（Ｌｉ）与蒸腾阻力（Ｄｒ）的关系符合方程Ｄｒ＝ａｅｂ／Ｌｉ。这样，根据光照强度对阻力的影响过程，把光照强度与蒸腾速率（Ｔｒ）的关系分成３个区段：①弱光照区，Ｔｒ＝Ｋ／Ｄｒ；②过渡区，Ｔｒ＝Ｋ·ψＬ－Ａ／Ｄｒ；③光饱和区，Ｔｒ＝ａ·ψＬ－Ａ＋ｂ，其中ａ、ｂ和Ｋ是系数。

Transpiration rate(Tr),stornatal resistence(Dr),leaf waterpatsential(Lp)and its corresponding environmental factors of seven tree speci-es have been n1easured with LI-1600 steady state prometer and pressure cham,ber.When the soil water potential in 2m depth is-0.04--0.20MPa, the lightintensity is the main factor to influence Tr, which is mainly influened by Dr.The relationsbip between Li and Dr can be expressed by following formula:Dr=aeb/Li,thus light intensity according to its influence on Tr can be divi-ded into three regions:Weak light region, Tr= K/Dr;Transition region,Tr=K·ψL-A/Dr; light saturation region, Tr=a·ψL-A+b where a,b and K are coe-fficients,ψL-A is the difference of leaf-air water potential.