新疆乌拉泊库区沙枣与胡杨光合特性比较

Comparison of Photosynthetic Characteristics of Elaeaguns angustifolia and Populus euphratica in Wulab Reservoir Area of Xinjiang

用Li-6400便携式光合测定仪,于2009年6~9月测定了新疆乌拉泊库区沙枣和胡杨2种荒漠树种的光合作用日变化,比较了它们光合与水分生理特性的季节动态变化.结果表明：（1）沙枣净光合速率（Pn）的日变化在6月份为典型双峰曲线,在8月和9月份也有微弱的双峰变化,7月份则表现为单峰曲线;胡杨的Pn日变化在6和9月份为双峰曲线,7和8月份为单峰曲线.（2）沙枣各月蒸腾速率（Tr）日变化均呈双峰曲线,胡杨的Tr日变化于6和7月份呈双峰曲线,在8和9月份呈单峰曲线.（3）沙枣水分利用效率（WUE）日变化规律不明显,胡杨各月WUE日变化表现为双峰曲线.（4）沙枣叶片的气孔导度（Gs）的日变化与其Pn的变化基本一致,而胡杨则没有这种现象.（5）气孔因素是引起沙枣光合午睡＂的一个原因,但不是引起胡杨Pn降低的主要因素;叶片大气水汽压亏缺（VPD）和气温（Ta）是共同影响沙枣和胡杨Pn的主要生态因子;沙枣平均Pn和Tr明显低于胡杨,而WUE则相反.

Li-6400 portable photosynthetic system was employed to measure diurnal changes of the photosynthetic characteristics of Elaeaguns angustifolia and Populus euphratica from June to September 2009 in Wulab reservoir area.The results showed that：（1）Diurnal course of Pn of E.angustifolia was double peak in June,August and September and single peak in July;diurnal course of Pn of P.euphratica was double peak curve in June and September and single peak in July and August.Diurnal course of Tr of E.angustifolia was double peak in grow season,while it was double peak in June,July and single peak in August,September for P.euphratica.Diurnal change of WUE of E.angustifolia was not apparent while it was double peak for P.euphratica.（2）Changes of Pn and Gs of E.angustifolia had the same trends.（3）Gs was one of the reasons leading to the middy depression of E.angustifolia,but it was not the reason for the depression of Pn of P.euphratica.（4）Average Pn and Tr of E.angustifolia were both lower than those of P.euphratica,but it was opposite to WUE.（5）VDP and Ta were the mainly ecological factors influencing Pn of E.angustifolia and P.euphratica.