The maximum carboxylation rate of Rubisco (V_cmax) and maximum rate of electron transport (J_max) for the biochemical photosynthetic model, and the slope (m) of the Ball-Berry stomatal conductance model influence gas exchange estimates between plants and the atmosphere. However, there is limited data on the variation of these three parameters for annual crops under different environmental conditions. Gas exchange measurements of light and CO₂ response curves on leaves of winter wheat and spring wheat were conducted during the wheat growing season under different environmental conditions. There were no significant differences for V_cmax, J_max or m between the two wheat types. The seasonal variation of V_cmax, J_max and m for spring wheat was not pronounced, except a rapid decrease for V_cmax and J_max at the end of growing season. V_cmax and J_max show no significant changes during soil drying until light saturated stomatal conductance (g_ssat) was smaller than 0.15 mol m⁻² s⁻¹. Meanwhile, there was a significant difference in m during two different water supply conditions separated by g_ssat at 0.15 mol m⁻² s⁻¹. Furthermore, the misestimation of V_cmax and J_max had great impacts on the net photosynthesis rate simulation, whereas, the underestimation of m resulted in underestimated stomatal conductance and transpiration rate and an overestimation of water use efficiency. Our work demonstrates that the impact of severe environmental conditions and specific growing stages on the variation of key model parameters should be taken into account for simulating gas exchange between plants and the atmosphere. Meanwhile, modification of m and V_cmax (and J_max) successively based on water stress severity might be adopted to simulate gas exchange between plants and the atmosphere under drought.

生化光合作用模型的最大Rubisco羧化速率（V _cmax）和最大电子传输速率（J _max）以及Ball-Berry气孔电导模型的斜率（m）影响植物与大气之间的气体交换估计。但是，在不同的环境条件下，一年生作物这三个参数变化的数据有限。在不同环境条件下，在小麦生长期，对冬小麦和春小麦叶片的光和CO ₂响应曲线进行了气体交换测量。V _cmax，J _max没有显着差异或两种小麦之间的m。春季小麦的V _cmax，J _max和m的季节变化不明显，除了在生长季节结束时V _cmax和J _max的快速下降。V _cmax和J _max在土壤干燥期间没有显着变化，直到光饱和气孔电导（g _ssat）小于0.15 mol m ^-2 s ^-1为止。同时，在以0.15 mol m ^-2的g _ssat分隔的两种不同供水条件下，m的差异显着s ^-1。此外，对V _cmax和J _max的误估计对净光合速率模拟有很大影响，而对m的低估会导致气孔导度和蒸腾速率的低估以及对水分利用效率的高估。我们的工作表明，在模拟植物与大气之间的气体交换时，应考虑到恶劣的环境条件和特定的生长期对关键模型参数变化的影响。同时，修改m和V _cmax（和J _max）可以根据干旱的严重程度依次采用模拟干旱条件下植物与大气之间的气体交换。