Time-lapse monitoring of root water uptake using electrical resistivity tomography and mise-à-la-masse: a vineyard infiltration experiment

Abstract

Abstract. This paper presents a time-lapse application of electrical methods (electrical resistivity tomography, ERT; and mise-à-la-masse, MALM) for monitoring plant roots and their activity (root water uptake) during a controlled infiltration experiment. The use of non-invasive geophysical monitoring is of increasing interest as these techniques provide time-lapse imaging of processes that otherwise can only be measured at few specific spatial locations. The experiment here described was conducted in a vineyard in Bordeaux (France) and was focused on the behaviour of two neighbouring grapevines. The joint application of ERT and MALM has several advantages. While ERT in time-lapse mode is sensitive to changes in soil electrical resistivity and thus to the factors controlling it (mainly soil water content, in this context), MALM uses DC current injected into a tree stem to image where the plant root system is in effective electrical contact with the soil at locations that are likely to be the same where root water uptake (RWU) takes place. Thus, ERT and MALM provide complementary information about the root structure and activity. The experiment shows that the region of likely electrical current sources produced by MALM does not change significantly during the infiltration time in spite of the strong changes of electrical resistivity caused by changes in soil water content. Ultimately, the interpretation of the current source distribution strengthened the hypothesis of using current as a proxy for root detection. This fact, together with the evidence that current injection in the soil and in the stem produces totally different voltage patterns, corroborates the idea that this application of MALM highlights the active root density in the soil. When considering the electrical resistivity changes (as measured by ERT) inside the stationary volume of active roots delineated by MALM, the overall tendency is towards a resistivity increase during irrigation time, which can be linked to a decrease in soil water content caused by root water uptake. On the contrary, when considering the soil volume outside the MALM-derived root water uptake region, the electrical resistivity tends to decrease as an effect of soil water content increase caused by the infiltration. The use of a simplified infiltration model confirms at least qualitatively this behaviour. The monitoring results are particularly promising, and the method can be applied to a variety of scales including the laboratory scale where direct evidence of root structure and root water uptake can help corroborate the approach. Once fully validated, the joint use of MALM and ERT can be used as a valuable tool to study the activity of roots under a wide variety of field conditions.

Imaging of plant current pathways for non-invasive root Phenotyping using a newly developed electrical current source density approach

“…This study describes the first direct and concurrent characterization of the root-soil current pathway and root architecture. Intrinsic differences in the root electrical properties of maize, cotton, grapevines, and orange trees emerge from the combined interpretation of our results with those presented by Mary et al (2018Mary et al ( , 2019, and Mary et al 2020).…”

“…In their study on field grapevines, Mary et al (2018Mary et al ( , 2019Mary et al ( , 2020 concluded that the CSD could be used to infer the root depth distribution. Because of the significant suberization of major roots in grapevines and orange trees, the electric current could penetrate deep into the root system before significant leakage occured.…”

“…Thus far, only indirect information obtained from invasive and time-consuming experiments have been available to address this issue (e.g., excavation and trimming). Mary et al (2018Mary et al ( , 2019, and Mary et al 2020) tested the combined use of ERT and Mise A La Masse (MALM) methods for imaging grapevine and citrus roots in the field. An approach hereafter called inversion of Current Source Density (iCSD) was used to invert the acquired data.…”

Three‐channel electrical impedance spectroscopy for field‐scale root phenotyping

“…(soil/field conditions). Mary et al (2020) also highlighted the irrigation influence on the current pathways in the SRS continuum. In light of the newly available evidence, Peruzzo et al (2020) discussed F I G U R E 1 Configuration of the electrodes and electrical impedance spectroscopy (EIS) channels for the (a) field and (b) hoop house acquisitions.…”

Modeling Plant Roots Spectral Induced Polarization Signature

“…For example, Mary et al. (2020) demonstrated that the joint application of electrical resistivity tomography and mise‐a‐la‐masse (MALM) provide information about the extent of active roots of a grapevine, and Peruzzo et al. (2020) show that MALM can also be applied for herbaceous plants.…”