中文摘要：

依据2010年对干旱荒漠区白麻的观测资料,对白麻气孔运动及其影响因子进行了分析研究并揭示了荒漠植物白麻的水分利用特征。结果表明：（1）白麻气孔导度的整体下降过程中有少许周期性波动,与净光合速率、蒸腾速率和胞间CO2浓度的转折点基本一致。（2）白麻气孔导度与影响因子之间进行偏相关分析,多元回归分析,通径分析,最终得出白麻气孔导度主要受光合有效辐射（PAR）、水汽压亏缺（VPD）、叶气温差（ΔT）和空气温度（Ta）的影响。（3）白麻水分利用效率和气孔限制值的关系可以看出：水分利用效率随着气孔限制值的增大而增大,随着气孔限制值的减小而减小。

英文摘要：

According to the observed data of Poacynum pictum （Schrenk.） Baill growing in arid desert area en- vironment in 2010, we studied the gas exchange characteristics of it under natural condition by using a portable Li - 6400 photosynthesis system. The results showed that ： （ 1 ） There are oscillations of the stomatal conductance in the diurnal course during the process of decline. Stomatal conductance turning points are consistent with net photosynthetic rate,transpiration rate and intercellular CO2 concentration. （2） The partial correlation analysis, multiple regression analysis, path analysis between stomatal conductance and its influencing factors of Poacynum picturn （Schrenk.） Baill showed that stomatal conductance is mainly affected by photosynthetically active radia- tion （ PAR）, vapor pressure deficit （ VPD）, leaf temperature difference （T） and air temperature （Ta）. （3） Water use efficiency of Poacynum picture （ Schrenk. ） Baill increases with the increase of stomatal limitation val- ue, decreases with the decrease of stomatal limitation.