中文摘要：

对沙坡头地区人工自然植被中的主要植物种油蒿（Artemisia ordosica）和柠条（Caragana korshinskii）光合特征进行了研究,分析了2种沙地灌木植物光合速率（Pn）、微环境因子（光合有效辐射PAR、气温t、相对湿度RH）以及植物叶片气孔导度（Gs）、胞间CO2浓度比（Ci）、气孔限制值（Ls）、蒸腾速率（E）及水分利用效率（WUE）等的变化特点.结果表明,2种沙地灌木植物的净光合速率日变化曲线呈双峰型.其中光合速率最大值出现在9：00左右,17：00左右出现第2峰值,这是沙地植物对强光照、高气温、低湿度的干旱自然环境条件的一种响应.2种沙地灌木植物光合作用的变化既受气孔因素的影响,也受非气孔因素的影响.其中在7：00-9：00与17：00-19：00时,两者光合速率的增加不仅仅是由于气孔导度的增加造成的,而9：00-15：00期间,植物光合速率下降的主要原因是气孔限制.以上各项光合特征指标的综合分析表明：在研究区自然环境条件下,油蒿比柠条具有更好的光合适应特性.

英文摘要：

The photosynthesis charateristics of A rtemisia ordosica and Caragana korshinskii in the artificial vegetation of Shapotou area were studied in this paper. Nine parameters were measured and calculated, ineluding photo flux density, air temperature, air relative humidity, net photosynthesis rate, stomatal conductance,intercellular CO2 concentration, stomatal limitation value, transpiration rate and water use efficiency. The results showed that there were two-peaks in diurnal curves of photosynthesis in plant leave. The first peak appeared at 9：00a. m.and the second at 17：00. These were the response of desert plants to the arid environmental factors, for example, strong photo flux density, high temperature and low humidity. Net photosynthesis rates of the two kinds of shrubs were mainly affected by stomatal factors from 9 ： 00to 15：00, but by non-stomatal factors from 7：00a. m. to 9：00.and from 17：00 to 19：00. The net photosynthesis and water use efficiency of A rtemisia ordosica was obviously higher than those of Caragana korshinskii. All of above made it clear that Artemisia ordosica was much more adaptable to the drought environment in Shapotou Area than Caragana korshinskii .