Estimate electron transport rate from chlorophyll a fluorescence by integrating the effects of light quantity and quality

In recent years, the electron transport rate (J) has received increasing attention, particularly in gas exchange models using chlorophyll a fluorescence (ChlaF). However, the response and variation of J require further investigation and validation under a range of light quantities and qualities. In this study, we measured gas exchange and ChlaF parameters under various controlled light conditions. J was calculated from the CO₂ fixation rate and ChlaF parameters as J_c and J_f, respectively. Significant variations in gas exchange properties and ChlaF parameters were observed in response to changes in light intensity and light quality. Specifically, light quality had a significant effect on J_f, with a relative effect of 46.65 %. Additionally, J_f exhibited significantly higher values than J_c under a substantial proportion of blue light. J_{f_γ}, which incorporates the effects of photosynthetic photon flux density (PPFD) and light components as correction factors (γ), can reconstruct J under dynamic light conditions, showing strong consistency with J_c (R² = 0.86, RMSE = 3.81 μmol photons m⁻² s⁻¹ and RPD = 2.57). These findings improve the accuracy of simulating instantaneous J under dynamic light conditions and provide valuable support for modeling gas exchange under natural conditions.