Modeling Plant Roots Spectral Induced Polarization Signature

Monitoring the growth, architecture, and function of plant roots is of great interest. One promising noninvasive geoelectrical monitoring approach is spectral induced polarization (SIP). However, the roots' SIP signature is underexplored, not well understood, and a mechanistic model has not been proposed. Here, we developed a mechanistic model for SIP's response of roots, which is based on the Poisson-Nernst-Planck equation. The modeling results suggest that the magnitude of root polarization is linearly related to the root's external surface area and that the polarization length scale is the root's diameter. We suggest that injecting a current to the plant's stem results in higher polarization associated with the root-cells' total surface area. In this case, the polarization length scale is the cell diameter. Overall, we quantified the link between the root's dimensions and their electrical signature, which may inspire SIP application for root phenotyping.