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西藏高原海拔高,大气压低,气温低且日较差变幅大,植物的光合作用受到显著的影响.单叶表观光合量子产额(αA)是反映植物光能利用和光合物质生产效率的基本参数,准确确定西藏高原的αA在研究高原C3植物光合作用和全球变化建模中具有重要意义.在海拔3688m,大气压为654×102Pa的拉萨高原生态试验站,利用Li-Cor6400光合仪测定了冬小麦旗叶在不同温度和胞间CO2浓度下的光响应曲线.利用0~150μmolm?2·s?1光量子通量密度下与净光合速率的初始斜率为αA指标,分析了高原稀薄大气环境下C3作物冬小麦的αA随叶温和胞间CO2浓度的变化规律.在30℃下,西藏高原冬小麦旗叶αA为0.0476±0.0038,与低海拔地区C3植物相比相差不大.αA主要受到温度和[CO2]/[O2]分压比的综合影响,以往测得αA可能由于仪器和数据处理方法的系统误差而低估了西藏高原真实值.αA随温度升高呈线性降低,温度每升高1℃,αA降低0.0007,随温度降低的梯度与低海拔地区相似.αA受到[O2]的显著影响,在一定[O2]下,随胞间CO2浓度增加而升高,呈双曲线关系.与低海拔地区相比,高原αA对CO2升高反应更敏感.
The photosynthesis of the plant was significantly affected by the high altitude of Tibet Plateau, low atmospheric pressure, low temperature and large daily amplitude, and the apparent photosynthetic quantum yield (αA) of single leaf was a function of plant photosynthetic energy utilization and photosynthetic production efficiency Basic parameters and accurate determination of αA in the Tibetan plateau is of great significance in the study of photosynthesis and global variation modeling of C3 plants in the plateau.At the Lhasa Plateau Ecological Experimental Station with an altitude of 3688m and an atmospheric pressure of 654 × 102Pa, Light Response Curves of Winter Wheat Flag Leaf at Different Temperatures and Intercellular CO2 Concentrations. The initial slope of net photosynthetic rate under 0-150 μmolm2 · s-1 photon flux density was measured as αA. The changes of αA of winter wheat with C3 crop were studied under the following conditions: the αA of flag leaf in winter wheat was 0.0476 ± 0.0038 at 30 ℃, which was similar to that of C3 plants at low altitude.αA was mainly affected by temperature and [ CO2] / [O2] partial pressure ratio, the αA measured in the past may underestimate the true value of the Tibetan plateau due to the systematic errors of instruments and data processing methods.αA decreases linearly with increasing temperature, And the αA decreased by 0.0007, the gradient decreasing with temperature was similar to that in the low altitude areas.αA was significantly affected by [O2] and increased with the increase of intercellular CO2 concentration under certain [O2], showing a hyperbolic relationship At high altitude, αA is more sensitive to elevated CO2 than low altitude.