Characterizing the CO2-response curve in photosynthesis and photorespiration: an innovative model for C3 plant species.

We introduce a novel model for characterizing the CO₂-response curve in photosynthesis, addressing the limitations of the Farquhar-von Caemmerer-Berry (FvCB) model by providing a more comprehensive framework for understanding photosynthetic responses to varying CO2 concentrations in C3 plants. The FvCB model, while instrumental in interpreting the photosynthetic response to CO2, does not directly estimate critical parameters such as maximum net photosynthetic rate, transit point from RuBP- to TPU-limited photosynthesis, and the CO2 compensation point in the presence of day respiration (R day). Our new model, referred to as Model I, incorporates these parameters and accounts for the R day, offering a nuanced understanding of plant physiological responses to CO₂ concentrations. The research also developed Model II, which does not require an explicit R day, addressing the challenges in measuring R day and providing an alternative for analyzing the CO₂-response curve. Both models were validated against empirical data, demonstrating their effectiveness in studying plant photosynthesis and photorespiration. The study concludes that the new models advance the FvCB model by predicting photosynthetic and photorespiratory responses under varying conditions, which is crucial for agricultural practices and ecosystem management in the context of climate change.