3种沙生灌木光合生理参数与土壤含水量的关系研究

在半干旱地区的盐池县，采用Li-6400便携式光合仪和TDR土壤水分测定仪，对不同土壤水分处理下的柽柳、小叶锦鸡儿和汤柴盆栽苗木的光合生理参数进行了测定，研究了叶片净光合速率（Pn）、羧化效率（Cm）、蒸腾速率（Tr）、水分利剧效率（WUE）对土壤含水量（SWC）的响应过程，并探讨了在不同土壤水分胁迫程度下3种灌木叶片光合作用的变化规律，最后确定了3种灌木在沙区适宜生长的土壤水分调控标准。研究表明：柽柳叶片Pn最高时的SWC为13．6％、小叶锦鸡儿叶片Pn最高时的SWC为13．4％、杨柴叶片Pn最高时的SWC为15．0％；Tr最高时3种灌木的土壤含水量临界值依次是：14．3％、15．1％、17．2％；柽柳、小叶锦鸡儿和杨柴维持叶片水分利用效率最高时的土壤含水量分别为10．1％、11．0％和9．9％；柽柳、小叶锦鸡儿和杨柴生长适宜的土壤水分范围分别为7．2％～10．1％、6．2％～11．0％和7．3％～9．9％。

Relationship between Soil Water Content and Photosynthetic Physiological Parameters of Three Kinds of Desert Shrubs

In Yanchi County, Li-6400 portable photosynthesis system was used to measure the photosynthetic parameters of three - year - old seedlings of Tamarix ramosissma, Caragana microphylla and Hedysarum mongolicum planted in pots with different soil water treatment. Meanwhile, a TDR moisture meter was used to measure SWC. The water use efficiency （WUE） was calculated according to WUE = Pn/Tr. The response processes of some parameters to SWC were studied, including net photosynthetic rate （Pn） , transpiration rate （Tr） , water use efficiency （WUE）. The effects of different soil water stress on the photosynthesis and the fitting range of SWC of three kinds of shrubs were explored and got. The results showed that when the highest Pn was coming forth, corresponding SWC of Tamarix ramosissma , Caragana microphylla and Hedysarum mongolicum were 13.6%, 13.4% and 15.0% respectively; when the highest Tr was coming forth, they were 14. 3%, 15.1% and 17.2% respectively ; the highest WUE of them were maintained under SWC of 10.1% , 11.0% and 9.9% ; the fitting ranges of SWC of the three shrubs were within 7.2% - 10. 1% , 6.2%- 11.0% and 7.3% -9.9%