2-DIMENSIONAL MODEL OF WATER TRANSPORT IN THE ROOT ZONE AND PLANT FOR CONTAINER-GROWN CHRYSANTHEMUM

A two-dimensional model was developed to quantify soil water transport in the plant-environment system of potted crops. This included three main components: water transport in root medium, root water uptake, and evapotranspiration. The root medium volume in which the plant was growing was divided into a series of layers of equal depth and concentric cylindrical shells of equal thickness. Water transport in the medium was simulated based on Darcy's law and mass conservation. Root water uptake was dependent on plant water potential, root resistance, and soil water status. Root resistance was a function of root length density and soil water content. Transpiration and evaporation were estimated based on meteorological data, calculated single-leaf stomatal conductance and surface resistances. The leaf area and canopy height increase sigmoidally with time. Required inputs into the model included initial soil water content (or soil matric potential) distribution, root length density distribution and environmental data (including irrigation data). The model simulated the patterns of soil water content, root water uptake, soil surface evaporation, plant transpiration, and plant water potential over the day. The model was validated with measured soil water content data. The simulation results of soil water content agree with the measured data reasonably well. The model reproduced the dynamics of soil water content under both irrigated and unirrigated conditions.