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

Abstract

Electrical impedance spectroscopy has long been considered a promising technique for noninvasive, in-situ root investigation because of its sensitivity to anatomy and physiology. However, the complexity of the root system and its coupling with stem and soil have hindered the signal interpretation and methodological upscaling to field applications. This study addresses these key issues by introducing three-channel acquisitions and their interpretation through Cole-Cole fitting. This solution could successfully decouple the impedance response of stem, roots, and soil, as well as provide convenient parametrization and comparison of their impedance signals. The methodological solution was tested on 80 wheat (Triticum aestivum L.) and 10 pecan [Carya illinoensis (Wangenh.) K. Koch] plants, the first extensive and field investigation. The investigation provided evidence of (a) proximal current leakage in herbaceous root systems, extending recent laboratory results and previous indirect field studies. (b) Major role of the plant stem, which has been a substantial concern raised in numerous studies. (c) Minor contribution from the soil, addressing the doubts on the comparability of results obtained in different soil conditions. All together, these evidences lead to indirect correlations between impedance signals and root traits. The explored solution is expected to support the adoption of the impedance spectroscopy, in line with the diffusion of multichannel impedance meters and growing interest in root physiology and phenotyping.

Imaging of the active root current pathway under partial root-zone drying stress: A laboratory study for Vitis vinifera

“…The number and the position of the stem and the return electrodes are a cause of uncertainties (electrode contact resistance, etc.). Peruzzo et al (2021), in a three channels experiment, were able to provide direct access to the response of stem and soil, which ultimately allowed the decoupling of the root response.…”

Combining Models of Root-Zone Hydrology and Geoelectrical Measurements: Recent Advances and Future Prospects

“…This impact can be direct and indirect. The former derives from the direct rootcurrent iteration and depends on the large surface area and capacitance of roots, which, in turns, has been linked to root physiology and suberization (Weigand, 2017;Peruzzo et al, 2021;Tsukanov and Schwartz, 2021). The latter, indirect impact, is a combination of the root-induced changes in the physical, chemical, and biological properties of the rhizosphere, e.g., RWU, root exudation, solute uptake and rhizosphere microbiome changes (Landl et al, 2021).…”

LEADER (Leaf Element Accumulation from DEep Roots): A nondestructive phenotyping platform to estimate rooting depth in the field

“…Ground penetrating radar (GPR) is being used for coarse roots of trees (Alani & Lantini, 2020; Hruska et al., 1999) and has agronomic applications to the coarser roots of root and tuber crops (Delgado et al., 2017; Guo et al., 2013; Wu et al., 2014) but is not yet capable of detecting fine roots, which are responsible for the majority of water and nutrient acqusition. New indirect methods include electrical impedance spectroscopy (Peruzzo et al., 2021), in‐field MRI (Bagnall et al., 2020), thermoacoustic imaging (Singhvi et al., 2022), ultra‐wideband microwave imaging (Shi et al., 2022), and electrical resistance tomography (Srayeddin & Doussan, 2009; Whalley et al., 2017), though all of these technologies are emerging. They are also depth limited based on the probe size and may not work in all soils.…”