采用Li-6400便携式光合测定系统，测定旱作条件下引种栽培的两种冰草属植物光合生理特性。结果表明，净光合速率Pn日变化均为双峰型，第1峰值均出现在10:00左右，第2峰值均出现在16:00。在午后14:00，由于气孔限制因素所致，出现了不同程度的光合“午休”现象，PAR是引起“午休”的间接因素。蒸腾速率Tr和气孔导度Gs日变化均为双峰曲线，峰值时间与净光合速率一致。胞间CO₂浓度Ci日变化近似V字形，14:00左右降至最低。两种植物叶片水压亏缺VPD变化趋势一致，而水分利用效率WUE日变化相反。上述各光合生理参数日均值大小表现为蒙古冰草高于沙生冰草。环境因子Ca和Ta对蒙古冰草的Pn日变化影响较大；Ca和RH对沙生冰草的Pn日变化影响较大，同时对两种植物的Tr日变化影响也较大；两种植物的Pn和Tr的主要生理影响因子是Gs和VPD。

The photosynthetic physiological characteristics of two species of Agropyron introduced and cultivated under dry conditions were measured by Li-6400 portable photosynthesis system. The results show that the diurnal variations of net photosynthetic rates have double peaks, with the first peak at 10:00, and the second at 16:00, with "noon break" at 14:00 obviously because of constraints caused by stomata, and with PAR as an indirect factor; the diurnal variations of transpiration rate and stomata conductance also have double peak, with the same peak times as the net photosynthetic rate; the diurnal variation of intercellular CO₂ concentration is roughly in a V-shape, with the minimum at 14:00; the diurnal variations of leave's water pressure deficit of two species are in the same trend, while the diurnal variations of water use efficiency are in the opposite trends; the averages of these photosynthetic physiological parameters of Agropyron mongolicum are higher than those of Agropyron desertorum. Ca and Ta have a greater effect on the diurnal dynamics of Pn of A. mongolicum, Ca and RH have a greater effect on the diurnal dynamics of Pn of Agropyron desertorum, while Ca and RH have a greater effect on the diurnal dynamics of Tr of two species, Gs and the VPD have a greater physiological effect on the diurnal dynamics of Pn and Tr of two species.