Stomatal Conductance Model Establishment and Simulation for Potted Apple Trees under Drought Stress

Plants may encounter drought stress frequently during their life cycles. In-depth studies of dynamic changes of stomatal conductance (Gs) under drought stress have important significance for understanding plant transpiration and fruit orchard irrigation. By constructing a photosynthesis-stomatal conductance-transpiration coupled model, the Gs dynamic changes of potted apple tree leaves under drought stress were simulated. The model parameters were determined by experimentation on potted apple trees (Malus domestica Borkh. cv. 'Fuji') under gradual drought stress. Numerical simulation results showed that Gs was primarily driven by the net radiation of leaves and relative humidity, Gs decreased linearly during soil droughts. Additionally, it was discovered that there was a strong interaction between microclimate factors and soil water potential. On sunny days, Gs exhibited a bimodal curve, with a maximum value of approximately 240 mmol·m-2·s-1 around 8:00 am. The results indicated that the coupled model was able to accurately simulate the dynamic changes of potted apple tree Gs under drought stress.