An experimental procedure for obtaining input parameters for the “ROOTMAP” root simulation program for peas (Pisum sativum L.)

The “ROOTMAP” model is designed to provide a realistic three-dimensional topological description of the growth of plant root systems. This paper describes and compares different techniques for obtaining ROOTMAP model input parameters from the measured properties of pea (Pisum sativum L.) root systems grown in aggregated soil at three values of penetration resistance (0.10, 0.25 and 0.51 MPa corresponding to bulk densities of 1.0, 1.2 and 1.4 Mg m-3 respectively). The elongation rate of the axis and the branching interval of laterals on the axis decreased with increasing penetration resistance. The resulting simulation gave a distribution of root contacts on the walls of a cylindrical container that was comparable to that observed. It was concluded that the model can simulate the growth and spatial distribution of the pea axis and first order laterals but simulation of the number and length of second order laterals is likely to be unreliable since their behaviour did not conform to the assumption of uniform elongation rate. The model now needs to be tested and validated under a range of experimental conditions.