阿克苏8种常见树种叶片水分利用效率特征

Characteristics of Leaf Water Use Efficiency of Eight Common Tree Species in Aksu

水分利用效率是植物生存的关键因子,客观反映植物对水分利用状况。用Li-6400以气体交换法测算叶片水分利用效率,探明阿克苏8种常见树种水分利用特征。结果表明,8种乔木水分利用效率随日太阳高度角(13°、35°、57°、71°、60°、39°、16°)变化趋势呈双峰型。瞬时水分利用效率(WUE)分别为:3.27、3.53、4.46、3.62、4.49、3.88mmol·mol-1和3.18mmol·mol-1;不同树种水分利用效率存在显著差异,以核桃和苹果最高;瞬时水分利用效率(WUE)与潜在水分利用效率(WUEi)在绿化树种和果树中分别表现出不同相关性,总体呈负相关(R2=-0.872、-0.723,p<0.05);7种影响因子(Pn、E、Gs、Ci、T、RH、Vpdl)与水分利用效率间存在相关关系,光合速率对水分利用效率影响最显著,气孔导度和蒸腾速率相互协同影响水分利用效率。大气湿度、胞间CO2浓度和饱和蒸汽压亏缺通过影响光合速率和气孔导度影响水分利用效率。在干旱区温度对水分利用效率影响复杂,需进一步研究。

Water use efficiency is one of the most important factors of plants＇ surviving,and it reflects the status of water use.In this paper,water use efficiency（WUE）of plant leaves were measured by using Li-6400 in Aksu,Xinjiang,China.The results demonstrated that WUE of sll the measured tree species showed a double-peak curve with solar altitude angles（13°,35°,57°,71°,60°,39°,16°）in daytime,in which the corresponding values of instantaneous WUE were 3.27,3.53,4.46,3.62,4.49,3.88mmol·mol-1,and 3.18mmol·mol-1,respectively.There were significant differences in WUE among different tree species,the highest for Juglans regia and Malus pumila.The greening trees and fruit trees had different correlations between instantaneous and potential WUE（R2=-0.72,-0.87,p0.05）.There was correlationship between WUEand 7 influencing factors,such as Pn,E,Gs,Ci,T,RH,and Vpdl.Photosynthetic rate had the most significant effect on WUE.Stomatal conductance and transpiration rate influenced on WUE synergistically.Atmospheric humidity,intercellular CO2 concentration and the saturatedvapor pressure influenced WUEthrough affecting the photosynthetic rate and stomatal conductance.Temperature effects on WUEin arid areas was more complex and needed to be further studied.