额济纳旗柽柳气体交换与水分利用效率日变化研究

对柽柳的若干生理、生态学特性进行初步研究.用LI-6400便携式气体分析系统对内蒙古额济纳旗七道桥＂天然胡杨林自然保护区＂内自然状态下柽柳（Tamarix ramosissima Ledeb）的净光合速率、蒸腾作用、水分利用效率及相应环境因子进行测定.结果表明,柽柳净光合速率日变化曲线呈双峰型,蒸腾速率日变化曲线呈单峰型,水分利用效率最高值出现在上午时分.根据光合作用的气孔限制与非气孔限制两个标准,柽柳从11：00开始光合速率下降主要由气孔因素引起,14：00之后光合速率下降主要由非气孔因素引起,即主要由叶肉细胞的光合活性降低造成.

The exchange of gas and daily change of water use efficiency for Tamarix ramosissima Ledeb in Ejina

The net photosynthetic rate,transpiration rate,water use efficiency of Tamarix ramosissima Ledeb as well as the relevant environment factors in the "natural forest reserve of the inartificial Diversiform-leaved poplar" in Qidaoqiao area of Ejina,were measured with a portable LI-6400 gas analysis system under natural condition.The results show that the diurnal course of net photosynthetic rate of T.ramosissima displays a two-peak pattern,and that of their transpiration rate a signal-peak pattern,their water use efficiency culminates in the morning.On the basis of two criteria of stomata limitation and nonlimitation of photosynthesis,the predominant limiting factor of T.ramosissima photosynthesis is stomata limitation beginning from 11:00.That is stomata nonlimitation after 14:00,here,its photosynthetic rate is mostly determined by the photosynthesis active.