Incorporating water and temperature factors enhanced the performance of the stomatal conductance model for soybeans cultivated under plastic film mulching with drip irrigation in the northeast black soil region

The application of plastic film mulching combined with drip irrigation can significantly alter the soil and water conditions for crop development. However, existing stomatal conductance models fail to adequately incorporate the effects of this practice on the physiological development of crops. This study employs three stomatal conductance models: Ball-Woodrow-Berry (BWB) model, Ball-Berry-Leuning (BBL) model, and Unified Stomatal Optimization (USO) model. This study introduces two model correction factors: the water response function (f(θ)) and the leaf-air temperature difference (∆T). These factors are utilized to simulate soybean stomatal conductance under various conditions, including plastic film mulching with drip irrigation, plastic film mulching without irrigation, drip irrigation without mulching, and control. The findings demonstrate that the USO model achieves superior performance, followed by the BBL and BWB models. Furthermore, the f(θ) correction factor outperforms the ∆T correction factor in enhancing model performance. The determination coefficients of the corrected BWB, BBL, and USO models increased by 15.2 %-102.2 %, 16.7 %-75.2 %, and 11.6 %-61.0 %, respectively. Meanwhile, the relative errors decreased by 7.5 %-43.2 %, 9.4 %-36.7 %, and 8.3 %-36.6 %, respectively. Additionally, the root mean square errors decreased by 8.2 %-27 %, 6.7 %-32.8 %, and 12.3 %-33.3 %. The corrected model exhibits strong reliability and universality across various soil water relative content and ∆T conditions, as evidenced by comparisons with the 95 % confidence intervals of observational data. The results of this study establish a theoretical foundation for the rational selection of stomatal conductance models in the northeast black soil region, thereby enhancing the simulation accuracy of water and carbon cycle processes under complex hydrothermal conditions.