Accurate estimation of the temporal and spatial root water uptake patterns in root zone is needed for an improved understanding of water and chemical transport dynamics in vadose zone. Rooting system is of great importance to describe the plant root water uptake directly. In this study, the diffusive root growth model was coupled with the Environmental Policy Integrated Climate (EPIC) crop growth model through changing the boundary condition, and a new semianalytical solution of the modified root diffusive model was derived considering the dynamic root length density distribution simulated by the EPIC crop growth model. To test the modified root growth model, the field-measured data of maize (Zea mays L.) and tomato (Solanum lycopersicum L.) root length density distribution were used for parameter optimization. A MATLAB program was developed by coupling the modified root diffusive model with the genetic algorithm to facilitate the parameters optimization. Results showed that the simulated root length density distribution at different times was in a good agreement with the observed values. The RMSE and bias values ranged from 0.22 to 0.25 cm cm^–3 and from −3.0 to 24.5%, respectively. The modified diffusive root growth model can therefore be used to simulate the two-dimensional root growth during the crop growing period.

中文翻译：

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修正二维扩散根生长模型的半解析解

需要准确估计根区的时间和空间根吸水模式，以更好地了解包气带中的水和化学输运动力学。生根系统对于直接描述植物根系吸水情况非常重要。在本研究中，通过改变边界条件将扩散根系生长模型与环境政策综合气候 (EPIC) 作物生长模型相耦合，并考虑模拟的动态根长密度分布推导出修正根系扩散模型的新半解析解。通过 EPIC 作物生长模型。为了测试修改后的根生长模型，玉米 ( Zea mays L.) 和番茄 ( Solanum lycopersicumL.) 根长密度分布用于参数优化。将修正后的根扩散模型与遗传算法相结合，开发了MATLAB程序，便于参数优化。结果表明，不同时间模拟的根长密度分布与实测值吻合较好。RMSE 和偏差值的范围分别为 0.22 至 0.25 cm cm ^–3和 -3.0 至 24.5%。因此，修改后的扩散根生长模型可用于模拟作物生长期间的二维根生长。