Theoretical and Experimental Study of Spectral Induced Polarization in a Single Plant Root

This study investigates the spectral induced polarization (SIP) response of single plant roots through theoretical modeling, numerical simulations, and preliminary experiments. SIP, a non-invasive geophysical method, shows promise for detecting root structures, but the underlying mechanisms remain unclear. A novel theoretical model was developed to explain root polarization behavior based on interfacial polarization across the cell membrane. Simulations using OpenFOAM explored the influence of cell geometry and packing density. Results revealed polarization coupling, a phenomenon where the electric field from one polarized cell affects adjacent cells in close proximity, leading to collective polarization. While the peak magnitude of phase shift remained relatively stable, the peak frequency decreased with increasing coupling length—the effective length over which cells are electrically coupled. Preliminary experiments using rapeseed roots grown in agar confirmed that young plants can generate measurable SIP responses, with phase shifts between 0.4 and 0.6 radians and peak frequencies below 40 kHz. These observations agree with model predictions, supporting the explanation of strong polarization signals in root cells. This combined theoretical and experimental approach provides new insight into root electrical behavior and lays the foundation for non-invasive root phenotyping under controlled and field conditions.