油蒿(Artemisia ordosica)光系统Ⅱ光化学效率对去除降雨的响应  

PSⅡ Photochemical Efficiency of Artemisia ordosica in Response to Rainfall Exclusion

作　　者：张明艳[1] 贾昕[1] 查天山[1] 秦树高[1] 吴雅娟[1] 任才[1] 

机构地区：[1]北京林业大学水土保持学院/宁夏盐池毛乌素沙地生态系统国家定位观测研究站/水土保持国家林业局重点实验室,北京100083

出　　处：《中国沙漠》2017年第3期475-482,共8页Journal of Desert Research

基　　金：国家自然科学基金项目(31270755;31200537;31361130340)

摘　　要：认识植物生理特征对极端干旱的响应有助于理解和预测气候变化对生态系统过程的影响。通过对叶绿素荧光连续监测,研究了油蒿(Artemisia ordosica)光系统Ⅱ(PSⅡ)最大光化学效率(F_v/F_m)、实际光化学效率(ΦPSⅡ)和非光化学淬灭(NPQ)对去除降雨的响应,旨在探讨干旱环境下PSⅡ的光保护机制。结果表明:油蒿叶片ΦPSⅡ和NPQ受光合有效辐射影响呈现出明显的日变化。与对照相比,去除降雨条件下ΦPSⅡ降低、NPQ升高。去除降雨降低了ΦPSⅡ对环境因子的敏感性,提高了NPQ对环境因子的敏感性。去除降雨条件下F_v/F_m的降低是由于PSⅡ反应中心的可逆性失活。这些结果表明极端干旱影响油蒿PSⅡ光化学效率;油蒿通过增加非辐射热耗散来抵抗干旱胁迫。Understanding the adaptive strategy of psammophyte plants under drought stress has drawn much research attention. Artemisia ordosicg is among the most important sand-fixing species in the Mu Us Sand- land. We conducted continuous in situ measurements of chlorophyll fluorescence on A. ordosica under both rainfall exclusion and natural precipitation conditions to examine the response of PSII photochemical efficien- cy to water stress. Continuous measurements of the chlorophyll fluorescence parameters were made in Au- gust, 2013 at the Yanchi Research Station, Ningxia Hui Autonomous Region, northwest China. Chlorophyll fluorescence parameters were measured on Artemisia ordosica under both rainfall exclusion and natural precipitation conditions using a Monitoring-Pam fluorometer. Climatic variables were simultaneously meas- ured with automated sensors. The maximum quantum yield of PSII photochemistry （Fv/Fm）, photochemical efficiency （ΦPSⅡ） and non-photochemical quenching （NPQ） were analyzed in relation to environmental fac- tors at the hour and diel scales. Photosynthetically active radiation was the direct control over ΦPSⅡ and NPQ at the diel scales, ΦPSⅡ and NPQ were significantly different in different water cinditions. The sensitivity of ΦPSⅡ to incident photosynthetically active radiation, air temperature and relative humidity was lower under rainfall exclusion than under natural rainfall, while the sensitivity of NPQ to these factors was increased by rainfall exclusion. The decrease of Fv/Fm was by the reversible inactivation of PSII reaction center. Our re- sults indicated that drought stress strongly affects the dynamics of chlorophyll fluorescence parameters of Artemisia ordosica, which copes with harsh desert environments by adaptively increasing its thermal dissi- pation to avoid damages to the photosynthetic apparatus.

关 键 词：叶绿素荧光 降雨 PSⅡ光化学效率 干旱半干旱区 

分 类 号：Q945.11[生物学—植物学]