美洲商陆光合光响应曲线及其模型拟合

为探讨不同光响应模型对美洲商陆光合特性的适用性,利用4种典型的光响应模型拟合了美洲商陆的光响应曲线,通过分析光合参数模拟值与实测值的拟合相似度,在4个模型中筛选最佳美洲商陆光响应模型。结果表明,直角双曲线模型、非直角双曲线模型、指数方程以及修正的直角双曲线模型对美洲商陆的光合光响应曲线都可以进行拟合,决定系数均为R2>0.99,但只有修正的直角双曲线模型可以计算它们的饱和光强。由各模型计算的光合参数可知,非直角双曲线模型求得的Pnmax远高于实测值,指数方程与修正的直角双曲线模型求得的Pnmax与实测值最为接近。直角双曲线、非直角双曲线模型以及指数方程求得的Isat均远低于实测值,唯有修正的直角双曲线模型求得的Isat与实测值最为相符。因此,修正的直角双曲线模型对于美洲商陆的光合光响应曲线的拟合以及各光合参数的求取最为适合。由修正的直角双曲线模型计算得到的美洲商陆的光合参数可知,美洲商陆的Pnmax为16.98μmol·m-2·s-1,Isat为1614.54μmol·m-2·s-1,Ic为14.14μmol·m-2·s-1,表明美洲商陆对光强具有较大的适应范围。

MODEL FITTING ON LIGHT RESPONSE CURVE OF PHOTOSYNTHESIS FOR PHYTOLA CCA AMERICANA

In order to investigate applicability of different light-response models to photosynthetic characteristics in Phytolacca americana, four typical models of light response curve were used to fit the light response curve of its leaf net photosynthesis. The optimal model was screened out by analyzing proximity between the simulated and measured values of photosynthetic parameters. The results showed that light response curves of photosynthesis for P. americana all could be fitted by rectangular hyperbolic model, non-rectangular hyperbolic model, index function model and modified rectangular hyperbolic model with determination coefficients of all R^2〉 0.99, but only modified rectangular hyperbolic model could calculate their saturation irradiances. According to calculated photosynthetic parameters by various models, Pn max estimated by non-rectangular hyperbola was far higher than the measured data, and Pn max fitted by exponential function and modified rectangular hyperbolic model were similar with the measured data./sat estimated by rectangular hyperbolic model, non-rectangular hyperbolic model and exponential function were far lower than the measured data, only/sat estimated by modified rectangular hyperbolic model were close to the measured data. Therefore,modified rectangular hyperbolic model was the best model in simulating light response curves of photosynthesis and calculate photosynthetic parameters for P. americana. Pn max, In, and Ic which were calculated by modified rectangular hyperbolic model was respectively 16.98μmol·m^2·s^-1, 1614.54μmol·m^2·s^-1 and 14.14 μmol·m^2·s^-1, which indicated that P. americana could be adaptive for illumination intensity in larger range.