Electrical characterization of the root system: a noninvasive approach to study plant stress responses

Abstract

A pot experiment was designed to demonstrate that the parallel, single-frequency detection of electrical capacitance (C R), impedance phase angle (Φ R), and electrical conductance (G R) in root-substrate systems was an adequate method for monitoring root growth and some aspects of stress response in situ. The wheat cultivars 'Hombar' and 'TC33' were grown in a rhyolite-vermiculite mixture under control, and low, medium, and high alkaline (Na 2 CO 3) conditions with regular measurement of electrical parameters. The photochemical efficiency (F v /F m) and SPAD chlorophyll content were recorded nonintrusively; the green leaf area (GLA), shoot dry mass (SDM), root dry mass (RDM), and root membrane stability index (MSI) were determined after harvest. C R progressively decreased with increasing alkalinity due to impeded root growth. Strong linear C R-RDM relationships (R 2 = 0.883-0.940) were obtained for the cultivars. Stress reduced |Φ R |, presumably due to the altered membrane properties and anatomy of the roots, including primarily enhanced lignification. G R was not reduced by alkalinity, implying the increasing symplastic conductivity caused by the higher electrolyte leakage indicated by decreasing root MSI. F v /F m , SPAD value, GLA, and SDM showed decreasing trends with increasing alkalinity. Cultivar 'TC33' was comparatively sensitive to high alkalinity, as shown by the greater relative decrease in C R , SDM, and RDM under stress, and by the significantly lower MSI and higher (moderately reduced) |Φ R | compared to the values obtained for 'Hombar'. Electrical root characterization proved to be an efficient non-intrusive technique for studying root growth and stress responses, and for assessing plant stress tolerance in pot experiments.

Responses of Parameters for Electrical Impedance Spectroscopy and Pressure–Volume Curves to Drought Stress in Pinus bungeana Seedlings

“…The injury of the cellular membrane was proven by the increased electrolyte leakage of the needles and stems from drought stress, as reported earlier [41,42]. Membrane stability index (MSI) of roots reflecting the electrolyte leakage also supported EIS results [32]. Due to its close relationship with the membrane injury by frost stress, r e was often used to estimate semi-lethal temperatures after freezing treatments, i.e., cold hardiness of conifer trees [43,44].…”

“…It has also been applied to evaluate growth of intact root system of herbaceous plants [27], tree roots [28,29] and the mycorrhiza colonization [30], as well as the frost damages of roots in small tree seedlings [31]. Recently, single-frequency impedance measurement was used to study plant response to alkaline stress [32]. Although the application of EIS in studying drought stress was not addressed before, the following studies showed that water content of organs was associated with the magnitude of EIS parameters.…”

Field phenotyping of plant roots by electrical capacitance – a standardized methodological protocol for application in plant breeding: a Review

“…Plant tissue acts as a capacitor when electric current passes through it, this tissue has an electrical capacitance (Cseresnyés et al, 2019;Postic and Doussan, 2016). The magnitude of this electrical capacitance can be measured in physical units -micro-and nanofarads.…”

Rapid beef quality detection using spectra pre‐processing methods in electrical impedance spectroscopy and machine learning

“…In medical field, EIS has proven to be valuable for diagnosing diseases, monitoring physiological changes (Gamal et al ., 2018). In agronomic field, EIS has been used for measuring soil moisture (Liu et al ., 2021b), plant growth (Repo et al ., 2005; Cseresnyes et al ., 2019), and fruit ripeness (Li et al ., 2019; Ibba et al ., 2020). In the field of food quality control, EIS can effectively assess the freshness (Perez‐Esteve et al ., 2014), water content (Yang et al ., 2013; Wei et al ., 2017), salt content (Ma et al ., 2016; Chen et al ., 2017; Schivazappa et al ., 2017), and fat content (Afonso et al ., 2020).…”