Abstract: This study describes the effects of temperature changes and enhanced UV-B radiation on net photosynthesis and related physiological parameter of straw-yellow gentian(Gentiana straminea Maxim.).Samples were analyzed using 20 W and 40 W UV-B lamps to increase UV-B radiation and with LI-6400 portable photosynthesis systems to change air temperature.Results show that net photosynthetic rate(P_n),stomata conductance(G_s),intercellular CO₂ concentration(C_i),transpiration rate(E) and water use efficiency(WUE) of straw-yellow gentian was higher under control than that under 20W or 40 W UV-B lamp treatments,while P_n at 25℃ was higher than that at 15℃ under increasing UV-B radiation treatments in August or under controls in September.Additionally,E of straw-yellow gentian at 25℃ was higher than that at 15℃,while G_s,C_i or WUE of straw-yellow gentian at 25℃ was lower than that at 15℃ under increasing UV-B radiation treatments.Results also show that P_n of straw-yellow gentian increased with increasing photosynthetic active radiation(PAR) when the PAR ranged from 0~800 μmol·m^-2·s^-1,while maximizing when PAR ranged from 800~2200 μmol·m^-2·s^-1,but no change when the PAR ranged from 2200~3000 μmol·m^-2·s^-1.The G_s or E of straw-yellow gentian increases with increased the PAR.The C_i of straw-yellow gentian decreases with increased PAR when the PAR ranged from 0~800 μmol·m^-2·s^-1,but did not change when the PAR ranged from 800~3000 μmol·m^-2·s^-1.The WUE of straw-yellow gentian increases with increased the PAR when the PAR ranged from 0~800 μmol·m^-2·s^-1,and it decreases slowly when PAR ranged from 800~3000 μmol·m^-2·s^-1.Results indicate that enhanced UV-B radiation results in decreased P_n,G_s,C_i,E and WUE of alpine meadows leaves that would be influenced by temperature variation.

Key words: UV-B radiation change, Photosynthesis, Alpine Meadows, Straw-Yellow Gentian, Qinghai-Tibet Plateau

摘要： 为了确定UV-B辐射增强和温度变化对高寒草甸植物生理过程的影响,以LI-6400便携式光合测定系统控制温度和紫外灯UV-B辐射增强方法,测定分析了UV-B辐射增强和温度变化对麻花艽(Gentiana straminea Maxim.)叶片光合作用及相关生理参数的影响。结果显示:麻花艽叶片净光合速率(P_n)、气孔导度(G_s)、胞间CO₂浓度(C_i)、蒸腾速率(E)和水分利用效率(WUE)在对照下较高,UV-B辐射为20W和40W处理下较低;8月,P_n在25℃下比15℃下显著高;9月,对照处理下P_n在25℃下比15℃下高。同时,E在25℃比15℃下高;G_s、WUE和C_i在25℃下比15℃下低。另外,麻花艽叶片P_n在光合有效辐射强度为0~800μmol·m^-2·s^-1时随光合有效辐射强度增加而增加幅度较大,800~2200μmol·m^-2·s^-1时增幅较小;G_s和E随光合有效辐射强度增加而增加;C_i在光合有效辐射强度0~800μmol·m^-2·s^-1时随光合有效辐射强度增加而呈现下降趋势,800~3000μmol·m^-2·s^-1变化不大;WUE在光合有效辐射强度0~800μmol·m^-2·s^-1时随光合有效辐射强度增加而呈现增加趋势,800~3000μmol·m^-2·s^-1时呈现下降趋势。说明UV-B辐射增强将对高寒草甸植物-麻花艽叶片光合作用及相关参数将产生极大影响,影响与温度变化有一定的关系。

关键词: UV-B辐射变化, 高寒草甸, 光合作用, 麻花艽, 青藏高原