花生不同光合-CO2响应曲线拟合模型的比较

为选择合适的数学模型来拟合花生(Arachis hypogaea L.)光合-CO₂响应曲线,比较了直角双曲线模型、Michaelis-Menten模型、非直角双曲线模型、指数函数、直角双曲线修正模型以及指数改进模型在模拟2个花生品种‘JS702’和‘JS713’的光合-CO₂响应曲线中的拟合度。结果表明,6种典型的CO₂响应模型均可对花生叶片的光合-CO₂响应曲线进行模拟,决定系数均达0.95以上。由计算的响应参数可知,不同模型拟合的2个品种的最大净光合速率均比实测值高,对于‘JS702’品种以指数改进模型计算最大净光合速率值最为接近实测值,而‘JS713’品种以直角双曲线修正模型、非直角双曲线模型和指数改进模型计算的最大净光合速率最为接近实测值。由直角双曲线修正模型与指数改进模型求解的饱和CO₂浓度与实测值差异较小,其余模型均与实测值差异较大。6个模型拟合的CO₂补偿点差异相对较小,‘JS702’品种的CO₂补偿点以直角双曲线修正模型、指数模型和指数改进模型与实测值最为一致;而‘JS713’品种的CO₂补偿点以直角双曲线修正模型与实测值最为一致。不同模型拟合的光呼吸速率2个品种均表现出以直角双曲线修正模型和指数改进模型较为接近实测值。综合分析,直角双曲线修正模型和指数改进模型比较适合用于拟合花生的光合-CO₂响应曲线。

Different Fitting Models of Photosynthesis-CO2 Response Curves of Peanut: Comparison

To select an appropriate model to fit the photosynthesis-CO₂ response curve of peanut, six typical models (rectangular hyperbolic model, Michaelis-Menten model, non-rectangular hyperbolic model, exponential model, modified rectangular hyperbolic model, and modified exponential model) were adopted to fit the photosynthesis-CO₂ response curves of two peanut (Arachis hypogaea L.) varieties (‘JS702’ and ‘JS713’). Results showed that all the six models could fit the photosynthesis-CO₂ response curves of the two peanut varieties (R ²>0.95). All the six models overestimated the maximum net photosynthetic rate (P_nmax), while the modified exponential model presented more realistic value for ‘JS702’, the non-rectangular hyperbolic model, the modified rectangular hyperbolic model and the modified exponential model presented more realistic values for ‘JS713’. The values of CO₂ saturation point (C_isat) estimated by modified rectangular hyperbolic model and modified exponential model had small difference with the measured data, however, the C_isat estimated by other four models were significantly different from the measured data. The estimated values of the CO₂ compensation point (Γ) by the six models were all close to the measured values, Γ calculated by modified rectangular hyperbolic mode, exponential model and modified exponential model were most consistent with the measured data for ‘JS702’, Γ calculated by modified rectangular hyperbolic model was more close to the measured data for ‘JS713’. The estimated values of the rate of photorespiration (R_p) by modified rectangular hyperbolic model and modified exponential model were close to the measured values for the two peanut varieties. All data suggested that the modified rectangular hyperbolic model and modified exponential model could well fit the photosynthesis-CO₂ response curve for peanut to study the photosynthetic characteristics.