中文摘要：

以中国科学院西北高原生物研究所培育的4个高原春小麦品种为材料，结合光合色素含量、叶面积等光形态参数的测定，采用调制叶绿素荧光分析技术，研究了青海香日德农业区春小麦抽穗期旗叶远轴向光面和近轴背光面的PSⅡ光化学量子效率及对强太阳光的适应性．结果表明：高原314、高原363和高原584的旗叶多呈直立转披型，高原913因叶面积小而宽其旗叶多倾向直立型；4个品种春小麦的光合色素有较大差异，且与充分暗适应的PSⅡ最大光化学效率（Fv／Fm）呈正相关；全晴天中午时分旗叶远轴向光面光合作用的光抑制现象较严重，但下午随太阳光强的降低，准确20min暗适应的Fv／Fm恢复很快，其PSⅡ反应中心属可逆失活；旗叶向光和背光部位间PSⅡ实际光化学效率（ФPSⅡ）和PSⅡ有效光化学效率（Fv＇／Fm’）的差异均达极显著，但两者的相对变化趋势截然相反，光化学猝灭系数（qp）和非光化学猝灭系数（NPQ）呈一致的变化趋势；尽管旗叶近轴背光面的ФPSⅡ和qp均较低，但Fv’／Fm’明显较高，说明其潜在的PSⅡ激发能捕获效率仍较大．研究证明光合机构的光化学和非光化学猝灭过程可有效耗散强光下累积的过量激发能，高原春小麦品种对青藏高原的强太阳光辐射具有很强的适应性．

英文摘要：

Taking four wheat varieties developed by Northwest Institute of Plateau Biology, Chinese Academy of Sciences, as test materials, with the measurement of content of photosynthetic pigments, leaf area, fresh and dry mass of flag leaf, the PS II photochemistry efficiency of abaxial and adaxial surface of flag leaf and its adaptation to strong solar radiation during the period of heading stage in Xiangride region were investigated with the pulse-modulated in-vivo chlorophyll fluorescence technique. The results indicated that flag leaf angle mainly grew in horizontal state in Gaoyuan 314, Gaoyuan 363 and Gaoyuan 584, and mainly in vertical state in Gaoyuan 913 because of its smaller leaf area and larger width. Photosynthetic pigments were different among the 4 varieties, and positively correlated with intrinsic PS II photochemistry efficiencies （ Fv/Fm）. In clear days, especially at noon, the photosynthetic photoinhibition was more serious in abaxial surface of flag leaf due to directly facing the solar radiation, but it could recover after reduction of sunlight intensity in the afternoon, which meant that no inactive damage happened in PS II reaction centers. There were significant differences of PS II actual and maximum photochemical efficiencies at the actinic light intensity （ФPSⅡ and Fv＇/Fm＇） between abaxial and adaxial surface, and their relative variation trends were on the contrary. The photochemical and non-photochemical quenching coefficients （qp and NPQ） had a similar tendency in both abaxial and adaxial surfaces. Although ФPSⅡ and qp were lower in adaxial surface of flag leaf, the Fv＇/Fm＇ was significantly higher, which indicated that the potential PS II capture efficiency of excited energy was higher. The results demonstrated that process of pho- tochemical and non-photochemical quenching could effectively dissipate excited energy caused by strong solar radiation, and there were higher adaptation capacities in wheat varieties natively cultivated in Qinghai-Tibetan Plateau area.