Testing a Convective-dispersive Model of Two-dimensional Root Growth and Proliferation in a Greenhouse Experiment with Maize Plants

Abstract Soil water, solute, heat and gas transport processes are often simulated using convective-dispersive or diffusion-type equations. These models have to be coupled with a root activity model to simulate plant development. To make such coupling easier, a generic convective-dispersive model of root growth and proliferation is proposed. The submodels of root growth rate and root convective and dispersive propagation rates are built so that statistical hypothesis testing can be used to reject an hypothesis on dependence of the rates on root and soil variables. The objective of this work is to test this model using maize plants grown in pots whose walls and bottom mechanically restrict root growth. Treatments included supplying the normal and double the normal amount of fertilizer and water. Plant development was monitored by weekly destructive harvests until 45 d after emergence. Root concentrations were determined in 24 sections of the pots along with shoot parameters. 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. Statistical hypothesis testing led to rejection of the hypothesis that root diffusivity did not depend on root concentration. The hypotheses that there is no geotropic root development and that root growth rate decreases with the growth of root concentration could not be rejected.

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