Testing a convective-dispersive model of two-dimensional root growth and proliferation in a greenhouse experiment with maize plants

Soil water, solute, heat and gas transport processes are often simulated us ing convective-dispersive or diffusion-type equations. These models have to be coupled with a root activity model to simulate plant development. To ma ke such coupling easier, a generic convective-dispersive model of root grow th and proliferation is proposed. The submodels of root growth rate and roo t convective and dispersive propagation rates are built so that statistical hypothesis testing can be used to reject an hypothesis on dependence of th e rates on root and soil variables. The objective of this work is to test t his model using maize plants grown in pots whose wails and bottom mechanica lly restrict root growth. Treatments included supplying the normal and doub le the normal amount of fertilizer and water. Plant development was monitor ed by weekly destructive harvests until 45 d after emergence. Root concentr ations were determined in 24 sections of the pots along with shoot paramete rs. The modular soil and root process simulator 2DSOIL was used to simulate root development. The model explained 73-77% of variation in the value of the logarithm of the root concentration measured in the experiments. Statis tical hypothesis testing led to rejection of the hypothesis that root diffu sivity did not depend on root concentration. The hypotheses that there is n o geotropic root development and that root growth rate decreases with the g rowth of root concentration could not be rejected.