中文摘要：

在青海省都兰县香日德镇东盛村，以中国科学院西北高原生物研究所培育的春小麦（Triticum aestivum）品种为材料，主要采用调制叶绿素荧光分析手段，研究了抽穗期旗叶光合作用的光抑制现象，并分析了非光化学猝灭组分的光诱导和非光诱导耗散的量子产量变化。结果表明，高原春小麦各品种间旗叶光合色素含量和比叶重存在差异；全晴天3个典型时段准确暗适应20min后的PSII最大光化学效率（Fv/Fm）的比较分析证实，高原春小麦存在着光合作用的光抑制现象，Fv/Fm的降低是由于PSII反应中心的可逆失活；稳态作用光下PSII有效光化学效率（Fv′/Fm′）易受持续强光胁迫的影响，而PSII实际光化学效率（ФPSII）在各春小麦品种间的差异略为明显；上下午间4个春小麦品种的光化学猝灭系数（qp）和非光化学猝灭系数（NPQ）呈较一致的变化趋势，显然卯和NPQ既属品种的内禀特性，又与强太阳光胁迫的累积密切相关；非光化学猝灭组分中光诱导的PSII调节性能量耗散的量子产量（ФNPQ）所占比例较大，下午时分ФNPQ的上调反映了高原春小麦对青藏高原持续强光胁迫的驯化适应。

英文摘要：

Aims Several local varieties of wheat （Triticum aestivum） developed by Northwest Institute of Plateau Biology, Chinese Academy of Sciences, are widely cultivated in the agricultural regions in Qinghai-Xizang Plateau. These varieties are well adapted to multiple environmental stresses such as low temperature, strong solar radiation, and drought. The objective of this study was to determine the responses of PSII photochemical efficiency to high solar irradiance in leaves of four wheat varieties. We examined whether photo-inhibition was appeared in wheat varie- ties and analysed variations of quantum yield of quenching due to light-induced and non-light-induced. Methods Field experiments were conducted on the farmland of Xiangride, which is located in the eastern side of Caidamu Basin, Qinghai Province. Four local wheat varieties were used during the heading stage in 2013. Meas- urements of photochemical efficiency and quantum yield were made on the abaxial surface of flag leaves facing the Sun by using a FMS-2 fluorometer, and the content of photosynthetic pigments and specific leaf weight （SLW） were concurrently determined. Pulse-modulated in-vivo chlorophyll fluorescence technique was used to obtain rapid information on photosynthetic processes. The maximum quantum efficiency of PSII photochemistry （Fv/Fm） was determined at 8：30, 12：00 and 16：30 on clear days after allowing for 20 min dark adaptation with leaf clips. The PSII maximal and actual photochemical efficiency （Fv＇/Fm＇ and ФPSII）, the PSII photochemical and non-photochemical quenching coefficient （qp and NPQ） were analyzed between morning and afternoon using in- ner actinic light with photosynthetically active photon flux density at 1 120 μmol photons.m-2.s-1. Furthermore, along with analysis of the fraction of PSII reaction centers that are opened （qL）, the quantum yield of quenching due to light-induced processes （ФNPQ） and non-light-induced processes （ФNO） were explored. Important findings There were signi