Abstract
Electrochemical impedance spectroscopy (EIS) has been widely applied to bioimpedance measurements in human and animal systems; however, its potential for direct plant monitoring remains less explored. This study uses Komatsuna (Brassica rapa) to examine the feasibility of using EIS for in situ detection of plant water stress. Impedance spectra are measured noninvasively and analyzed using an equivalent circuit model designed to separate plant-related electrical properties from the electrode-plant interface. Changes in the low-frequency impedance region were observed under both irrigation and drying conditions, while the high-frequency response remained relatively stable. In particular, variations in the extracellular resistance parameter (R(o) ) preceded visible water-stress symptoms and continued even after visual changes became indistinguishable. Although the number of tested plants was limited, these results suggested the potential of EIS as a rapid and cost-effective tool for early, in situ assessment of plant water status. The present study provides a proof-of-concept for extending bioimpedance-based approaches to plant systems, with implications for precision agriculture and plant physiology research.