西藏高原小麦叶片表观量子产额和最大光合速率的确定

Qinghai-Tibetan Plateau is characterized by high elevation and lower air pressure. The air pressure and air mass density is one third less than that in the sea level. Therefore, low CO2 density is one of the key factors controlling plant photosynthesis. Apparent quantum yield and maximum photosynthetic rate are two important parameters for photosynthesis modelling. However, there is little research in this field in the Plateau. We measured these parameters for wheat by using Li-Cor 6400 photosynthesis system. The apparent quantum yield was 0.049 mmol CO2 /mmol photons in average, ranging from 0.0398~0.0570mmol CO2 /mmol photons from 15~35°C. And maximum photosynthesis rate is 22.57 mmol CO2 m-2 s-1, ranging from 14.50~29.0 mmol CO2 m-2 s-1 Apparent quantum yield j and maximum rate Pmax are negatively correlated with leaf temperature. The average lapse rates of j and maximum rate Pmax were0.0007 mmol CO2 /mmol photons and 0.505 mmol CO2 m-2 s-1 respectively. Low airpressure is the root cause for low j and Pmax in the plateau.

通过配气钢瓶和燃气开顶式同化箱控制叶室CO2浓度试验,测定在现时和全球变化情景下高原小麦叶片表观量子产额和最大光合速率的值,分析其与环境因子的关系,验证有关表观量子产额和最大光合速率理论推算的高原适用性。此研究前人少有涉及，为利用模拟手段研究和预测青藏高原植被对全球变化的响应程度打下坚实的基础，极具高原特色。