Comment on bg-2023-58

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> Understanding root signals and their consequences on the whole plant physiology is one of the keys to tackling the water-saving challenge in agriculture. The partial root-zone drying (PRD) method is part of an ensemble of irrigation strategies that aim at improving water use efficiency. To reach this goal tools are needed for the evaluation of the root&rsquo;s and soil water dynamics in time and space. In controlled laboratory conditions, using a rhizotron built for geoelectrical tomography imaging, we monitored the spatio-temporal changes in soil electrical resistivity for more than a month corresponding to six Partial Rootzone Drying (PRD) cycles. Electrical Resistivity Tomography (ERT) was complemented with Electrical Current Imaging (ECI) using plant stem-induced electrical stimulation. We demonstrated that under mild water stress conditions, it is practically impossible to spatially distinguish the PRD effects using ECI. We evidenced that the Current Source leakage depth varied during the course of the experiment but without any significant relationship to the soil water content changes or transpiration demand. On the other hand, ERT showed spatial patterns associated with irrigation and, to a lesser degree, to RWU. The interpretation of the geoelectrical imaging with respect to root activity was strengthened and correlated with indirect observations of the plant transpiration using a weight monitoring lysimeter and direct observation of the plant leaf gas exchanges.