不同CO2浓度下番茄幼苗叶片的光能利用效率

光能利用效率(LUE)是评价植物叶片光能利用能力的重要参数,更是影响生态系统生产力大小和质量的主要因素.本文基于植物光合作用对光响应的机理模型推导出植物叶片的光能利用效率模型以及叶片的最大光能利用效率(LUE_max)和对应的饱和光强(I_L-sat)的数学表达式,并用光能利用效率模型研究了番茄幼苗叶片在CO₂浓度分别为350、450、550和650 μmol·mol^-1下的光能利用效率.拟合结果表明: 所推导的叶片光能利用效率模型可以很好地描述4种CO₂浓度条件下番茄幼苗叶片的光能利用效率;在这4种CO₂浓度条件下,番茄的LUE_max在光合有效辐射(I)为70～90 μmol·m^-2·s^-1时就可以达到;番茄在CO₂浓度为550和650 μmol·mol^-1时叶片的LUE_max和I_L-sat没有差异.产生这种现象的原因可能是由于番茄幼苗长时间处于较低光强下,番茄幼苗叶片的光合功能已经适应了低光强环境,以致于高CO₂浓度难以改变它的捕光色素分子的内秉特性,如有效光能吸收截面以及处于激发态和基态色素的比例等.

Light-use efficiency of tomato seedling leaves at different CO2 concentrations.

Light-use efficiency (LUE) is an important parameter to assess light energy absorption of leaf. Especially, it is a key factor to affect production and quality of ecosystem. A model of LUE was developed based on a mechanistic model of light-response of photosynthesis. The maximum LUE (LUE_max) and corresponding saturation irradiance (I_L-sat) were deduced according to the LUE mo-del. At CO₂ concentrations of 350, 450, 550 and 650 μmol·mol^-1, the light-response curves of LUE of tomato seedling leaves were simulated. The results showed that the model of LUE described well the response curves of light use efficiency of tomato seedling leaves at four CO₂ concentrations. LUE of tomato seedling leaves reached the maximum value at photosynthetically active radiation between 70-90 μmol·m^-2·s^-1. There were no difference of LUE_max and I_L-sat at 550 and 650 μmol·mol^-1. Regarding this phenomenon, it was hypothesized that the photosynthetic functions of tomato seedling leaves had acclimated to the low irradiance in greenhouse so that the intrinsic cha-racteristic of light-harvesting pigments such as the effective light absorption cross-section of light-harvesting pigments and ratio of pigment molecules in the excited state to ground state had hardly changed at high CO₂ concentrations.