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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 Li-6400 portable photosynthesis system was used to measure the photosynthetic characteristics of two species of Agropytes under the condition of dry cultivation. The results showed that diurnal variation of net photosynthetic rate Pn was bimodal, the first peak appeared around 10:00, the second peak appeared at 16:00. At 14:00 in the afternoon, due to stomatal limitation, there were different degrees of photosynthesis “lunch break ” phenomenon, PAR is the indirect factor causing “lunch break ”. The diurnal changes of transpiration rate Tr and stomatal conductance Gs were bimodal curve, and the peak time coincided with the net photosynthetic rate. The Ci diurnal variation of Ci was approximately V-shaped and dropped to the lowest around 14:00. The changes of water deficit VPD in two plant leaves were the same, while the daily variation of water use efficiency (WUE) was opposite. The average daily photosynthetic parameters of the above photos showed the Mongolian snow grass is higher than the sand grass. Environmental factors Ca and Ta have a significant effect on diurnal variation of Pn in P. crassicarpa; Ca and RH have a significant effect on the diurnal variation of Pn in S. alfredii, The main physiologic influencing factors of Pn and Tr are Gs and VPD.