干旱区3种典型灌木光合特性及其对环境因子的响应

通过对库布齐沙漠东段优势灌木种柠条、沙柳和油蒿的光合特性及生境气象环境因子进行测定,比较了灌木净光合速率、蒸腾速率、瞬时水分利用效率、叶绿素总含量等指标在生长季不同时期的差异性,并探讨了净光合速率与生理因子及环境因子的关系。结果表明:(1)3种灌木净光合速率与蒸腾速率在生长季均呈单峰曲线变化,生长盛期显著大于生长后期;净光合速率均值由大到小排序为油蒿(25.8μmol/(m 2·s)、沙柳(24.9μmol/(m 2·s)、柠条(21.1μmol/(m 2·s),油蒿的光合作用和有机物积累能力最强。(2)相同生境下,沙柳的平均水分利用效率为4.1μmol/mmol,明显高于柠条(3.4μmol/mmol)和油蒿(3.0μmol/mmol),沙柳的抗旱性及环境适应能力最强。(3)生理及环境因子共同影响灌木光合作用,柠条净光合速率与蒸腾速率、气孔导度、光合有效辐射、空气和土壤温度呈显著正相关,与大气相对湿度呈显著负相关;沙柳净光合速率与蒸腾速率、叶绿素总含量、光合有效辐射、土壤温度呈显著正相关;油蒿净光合速率与气孔导度、风速及光合有效辐射呈显著正相关。

Photosynthetic Characteristics of Three Typical Shrubs in Arid Region and Their Response to Environmental Factors

The photosynthetic characteristics and environmental factors of three dominant shrubs,namely Caragana microphylla,Salix psammophila and Artemisia ordosica in the eastern section of Hobq Desert were determined in this study.The differences of net photosynthetic rate,transpiration rate,instantaneous water use efficiency and total chlorophyll content of shrubs in different growth seasons were compared,and the relationship between net photosynthetic rate and physiological factors and environmental factors was also discussed The results showed that:1)The net photosynthetic rate and transpiration rate of the three shrubs all showed a single peak curve in the growth season,and these two indexes were significantly higher in the bloom growth period than in the late growth period.The mean sequence of the net photosynthetic rate was in A.ordosica〔25.8μmol/(m 2·s)〕>S.psammophila〔24.9μmol/(m 2·s)〕>C.microphylla〔21.1μmol/(m 2·s)〕,and A.ordosica had the strongest photosynthetic capacity and organic accumulation ability.(2)In the same habitat,the average water use efficiency of S.psammophila was 4.1μmol/mmol,which was significantly higher than that of C.microphylla〔3.4μmol/mmol)and A.ordosica(3.0μmol/mmol),and S.psammophila had the strongest drought resistance and environmental adaptability.(3)Physiological and environmental factors affected the photosynthesis of shrubs comprehensively.The net photosynthetic rate of C.microphylla was positively correlated with transpiration rate,stomatal conductance,photosynthetically active radiation,air and soil temperature,and negatively correlated with atmospheric relative humidity.The net photosynthetic rate of S.psammophila was significantly positively correlated with transpiration rate,total chlorophyll content,photosynthetically active radiation and soil temperature.The net photosynthetic rate of A.ordosica was significantly positively correlated with stomatal conductance,wind speed and photosynthetically active radiation.