Abstract:

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.

Key words: peanut, photosynthesis-CO₂ response curve, model, the maximum net photosynthetic rate, the CO₂ saturation point