| Taking the endangered plant Alsophila spinulosa as the and research material，the photosynthetic light response curve was measured by Li-6400 portable photosynthetic system, and the application models of the right-angle hyperbola model, the non-rectangular hyperbola model, and the modified right-angle hyperbola model was studied. The applicability of different models to the light-generating response and CO2 response was discussed. The results showed that the light response curve of A. spinulosa was fitted by the modified right-angle hyperbolic model. The light response parameter αof A. spinulosa was 0.077, Pnmax, Iisat, Ic and Rd was 8.162, 917.96, 16.021 and -0.975 μmol/m2·s, respectively. The CO2 response parameter α was 0.035, Cisat, Pmax, Γ and RP was 1 577.624, 14.170, 61.666 and -2.028 μmol/m2·s, respectively. The modified rectangular hyperbola model fitted the photoresponse and CO2 response data of helium well, and calculated the photosynthetic parameters directly and accurately. At the same time, the photoresponse data of the photoinhibition part was well processed. High-light intensity rectangular hyperbola model and non-rectangular hyperbola model could not deal with light suppression problem. Corrected light saturation point and CO2 saturation point in rectangular hyperbola model were higher than right-angle hyperbola model and non-right-angle hyperbola model, the performance of maximum net photosynthesis rate was opposite. The light compensation point, dark respiration rate, photorespiration rate and CO2 compensation point were between the hyperbola and non-right hyperbola models. The simulated right hyperbola model was closest to the measured value. A. spinulosa has a certain resistance to negative, could adapt to certain low light environmental conditions, and have a wide range of adaptation to CO2. The modified right-angle hyperbola model is an ideal model to fit the photosynthetic-photoresponse curve of A. spinulosa. This model can simulate the light energy efficiency of alfalfa plants and provide reference for the effective protection of alfalfa plants. |
