SIMULTANEOUS MODELING OF TRANSIENT 3-DIMENSIONAL ROOT-GROWTH AND SOIL-WATER FLOW

A model is presented for the simultaneous, dynamic simulation of soil water movement and plant root growth. Root apices are translocated in individual growth events as a function of current local soil condition s. A three-dimensional finite-element grid over the considered soil do main serves to define the spatial distribution of soil physical proper ties and as framework for the transient water flow model. Examples ill ustrate how field-observed morphology of root systems can be approxima ted by including even a coarsely discretized description of the soil e nvironment. Intended as a tool for testing of hypotheses on soil-plant interaction, simulations can be performed for different levels of mod el complexity, depending on how much information is available. At the simplest level, root growth is simulated without soil water uptake, wh ereas the most comprehensive level includes growth of the shoot acid d ynamic assimilate allocation to root and shoot.