黄土高寒区不同土壤水分条件下银水牛果幼苗光响应研究

为了给黄土高寒区造林树种的选择和水分的有效利用提供理论依据和科学指导,本研究在青海大通县试验基地通过人工控制土壤水分的方法,利用Li-6400便携式光合测定系统对银水牛果气体交换参数因子的光响应进行分析。结果表明:银水牛果的的净光合速率(Pn)、蒸腾速率(Tr)、水分利用效率(WUE)与光合有效辐射(PAR)及土壤含水量(SWC)密切相关。(1)当PAR为500～2000μmol/(m2·s)、SWC为14.35%～21.5%时,既能保证银水牛果叶片具有较高的Pn,又能维持较高的WUE。(2)与其他水分处理相比,在轻度水分胁迫下银水牛果既能在低光强下具有较高的光能利用能力,又能适应强光辐射,光适应生态幅度较宽。(3)在适度缺水条件下,银水牛果的光合作用强于供水充足的植株,而且适度水分亏缺并未使产量显著降低,反而使WUE提高。在受到较严重的水分胁迫时,银水牛果的WUE在PAR为500～2000μmol/(m2·s)时,仍保持较高。说明银水牛果具有高效用水的生理特征,在受到水分胁迫时,能通过自身生理调节来适应外界水分等环境变化,维持较高的WUE。综上所述,银水牛果对逆境(强光、干旱)具有较强的适应能力,可以作为黄土高寒区的造林树种进行推广种植。

Study on Light Response of Shepherdia Argentea Seedlings under Different Soil Moisture Conditions in Loess Plateau Region

In order to provide a theoretical basis and scientific guidance for the selection of tree species and effective utilization of water, by using Li-6400 portable photosyntometer, light response of gas exchange parameters ofShepherdia argentea seedlings under different soil moisture conditions was analyzed in Datong experimental base of Qing Hai. The results showed thatPn ,Tr andWUE were significantly correlated with PAR andSWC .（1）WhenPAR was 500～2000 μ mol/（m2·s） andSWC was 14.35%～21.5%,Shepherdia argentea leaves had highP n andWUE .（2）Compared with other water conditions,Shepherdia argentea had higher photosynthetic capacity and stronger adaptability to light conditions at lowPAR under the mild water stress condition.（3）Photosynthesis of Shepherdia argentea was higher under the moderate water stress condition than those under other water conditions, so WUE of Shepherdia argentea did not decline but increased. WhenPAR was 500～2000 μmol/（m2·s） under the severe water stress condition,WUE was still at high level, which indicated thatShepherdia argentea was of high efficiency of water utilization and could adapt to changes of water and other environmental factors through its own physical regulations, so as to keepWUE at high level. It was concluded thatShepherdia argentea had high ability to adapt stress （strong light, drought） and can be widely cultivated in loess plateau region.