非均匀水势下作物根系吸水模型分析

Water uptake model analysis of crop roots under non-uniform water potential

根据土壤-根系统中水分守恒和水势对水分运输作用的原理, 建立了土壤中非均匀水势作物根系吸水模型。在该模型中, 分别对一次函数和指数函数两种不同的非均匀土壤水势的表达形式建立模型, 并对非均匀水势和均匀水势下模型的解析解之间的关系进行了探讨; 利用该模型讨论根系的吸收阻力和木质部传导阻力的比率对根吸水的影响; 运用阻力比率的合理生理范围确定根生长的优化长度。结果表明: 在特定情况下, 非均匀水势下的根系吸水模型可以用于均匀水势, 对Poiseuille公式进行修正后得到的根的优化长度接近实际值。

Aims Our objective is to consider a water uptake model of crop roots under non-uniform water potential. This is based on principles of water conservation in soil-plant system and water potential＇s driving force on water transport. Methods We introduced two expressions of non-uniform soil water potential, linear and exponential functions, and compared the analytical solutions under non-uniform and uniform water potentials. This model is used to analyze the effect of ratio of radial resistance and axial resistance on plant water uptake and to determine the optimal root length within a reasonable range of this ratio. Important findings In certain circumstances, the water uptake model for plant roots with non-uniform water potential can be simplified to a uniform water potential model, and the optimal root length is close to the actual value after the Poseuille formula is changed to fit plant vessels.