Electrical capacitance of roots in relation to plant electrodes, measuring frequency and root media

Rajkai, Kálmán; Végh, Krisztina R.; Nacsa, T.

doi:10.1556/aagr.53.2005.2.8

Cited by 36 publications

(47 citation statements)

References 10 publications

(14 reference statements)

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“…One terminal of the instrument was connected to the ground electrode ie a stainless steel rod (6.3 mm in diameter and 15 cm long) inserted to a depth of 10 cm into the potting soil and positioned 6 cm away from the stem base. The second terminal was attached to the plant stem with a spring tension clamp (Beem et al, 1998;Kendall et al, 1982;Rajkai et al, 2005). Since plant electrode placement strongly affects electrical measurements, a distance of 20 mm was precisely maintained between the lower edge of the clamp and the soil surface (root neck).…”

Section: Methodsmentioning

confidence: 99%

“…Thus, the polarized membrane plays the role of a dielectric in a capacitor, where plant solution provides the first plate and soil solution is the second one. Rajkai et al (2005) recommended a twodielectric (series-connected root and soil dielectric) capaInt. Agrophys., 2013Agrophys., , 27, 377-383 doi: 10.2478Agrophys., /intag-2013 Role of phase angle measurement in electrical impedance spectroscopy continuity.…”

Section: Introductionmentioning

confidence: 99%

“…A great part of the previous investigations was executed either at the conventional current frequency of 1 000 Hz or at other arbitrarily chosen operating frequency without paying attention to measuring F (Rajkai et al, 2005). We hypothesized thatbesides the edaphic factors described above -the frequency-dependent change in the capacitive strength (indicated by F and D) may also contribute to the weakening of the correlation between the EI and the root system size.…”

Section: Introductionmentioning

confidence: 99%

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Role of phase angle measurement in electrical impedance spectroscopy

Cseresnyés¹,

Rajkai²,

Vozáry³

2013

International Agrophysics

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A b s t r a c t. Importance of phase angle measurement during the application of electrical impedance spectroscopy was studied by executing pot experiments with maize. Electrical impedance, phase angle (strength of capacitive character), and dissipation factor in the plant-soil system were scanned between 100 and 10 000 Hz current frequency. The frequency-dependent change in the phase angle could be described by optimum curves culminating within 920-3 650 Hz. Since the rate of energy dissipation is independent of root extent, the higher phase angle and lower energy dissipation were associated with the higher coefficient of determination achieved for the root electrical impedance -root system size (root dry mass and root surface area) regressions. The characteristic frequency selected on the basis of phase angle spectra provided a higher significance level at statistical comparison of plant groups subjected to stress conditions influencing root development. Due to the physicochemical changes observable in aging root tissue, the apex of phase angle spectra, thus the characteristic frequency, shifted continuously toward the higher frequencies over time. Consequently, the regularly repeated phase angle measurement is advisable in time-course studies for effective application of the electrical impedance method, and the systematic operation at the same frequency without determination of phase angle spectra should be avoided.K e y w o r d s: dissipation factor, root capacitance, electrical impedance spectroscopy, phase angle, root surface area INTRODUCTIONDestructive root investigation methods, such as soil cores, in-growth cores, or monoliths are unsuitable for continuous monitoring of root development or activity in response to changing environmental conditions. The applicability of the non-destructive ground penetrating radar, radioactive tracers, MRI or X-ray imaging techniques is also strongly limited in many cases: providing little resolution of root structure (detect clearly coarse roots only), these methods are not adapted for quantification of root surface area and examination of many plant phenomena related to root development (Cao et al., 2010;Èermák et al., 2006). Conversely, electrical impedance (EI) and electrical capacitance (EC) measurements in a plant-soil system offer good opportunities of rapid in situ investigation of the root system size and root activity without any intrusion into plant life function. By fixing an electrode at the plant stem and embedding the other one in the soil and connecting them by an LCR-instrument, the measured root EI and EC are directly correlated with root mass, root length, or root surface area (Chloupek, 1972;Ozier-Lafontaine and Bajazet, 2005;Rajkai et al., 2002). EI and EC methods have been used for investigation of detached plant tissues and organs subjected to various stress conditions (cold acclimation, freeze-thaw injury, drought, nutrient deficiency, or pathogen infection) as well as for studying intact root systems of plants cultivated in soil or grown in hydro...

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Role of phase angle measurement in electrical impedance spectroscopy

Cseresnyés¹,

Rajkai²,

Vozáry³

2013

International Agrophysics

Self Cite

View full text Add to dashboard Cite

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“…One terminal of the instrument was connected to the plant stem with a spring tension clamp fixed at 15 mm above the substrate level and a second one earthed by a stainless steel rod (6 mm ID, 15 cm long) inserted to a depth of 10 cm into the substrate 5 cm away from stem base. Electrocardiograph paste was smeared around the stem to keep up electrical contact (Rajkai et al, 2005). Each EC measurement was carried out after the application of Hoagland solution and irrigation to field capacity in order to ensure the optimal and equal water status and the same ionic content in the planting medium.…”

Section: Methodsmentioning

confidence: 99%

“…Thus the polarised membrane plays the role of a dielectric in a capacitor having a capacitance proportional to the charge stored on the membrane surfaces. Rajkai et al (2005) recommended a two-dielectric (series-connected root and soil dielectric) capacitor model, where the capacitive character of the soil solution was also considered. Edaphic factors having influence on the accuracy of EC measurements (ie water saturation, soil texture and salinity, electrode placement) were investigated as well (Dalton, 1995;Ozier-Lafontaine and Bajazet, 2005).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous monitoring of electrical capacitance and water uptake activity of plant root system

Cseresnyés¹,

Takács²,

Füzy³

et al. 2014

International Agrophysics

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A b s t r a c t. Pot experiments were designed to test the applicability of root electrical capacitance measurement for in situ monitoring of root water uptake activity by growing cucumber and bean cultivars in a growth chamber. Half of the plants were inoculated with Funneliformis mosseae arbuscular mycorrhizal fungi, while the other half served as non-infected controls. Root electrical capacitance and daily transpiration were monitored during the whole plant ontogeny. Phenology-dependent changes of daily transpiration (related to root water uptake) and root electrical capacitance proved to be similar as they showed upward trends from seedling emergence to the beginning of flowering stage, and thereafter decreased continuously during fruit setting. A few days after arbuscular mycorrhizal fungi-colonization, daily transpiration and root electrical capacitance of infected plants became significantly higher than those of non-infected counterparts, and the relative increment of the measured parameters was greater for the more highly mycorrhizal-dependent bean cultivar compared to that of cucumber. Arbuscular mycorrhizal fungi colonization caused 29 and 69% relative increment in shoot dry mass for cucumbers and beans, respectively. Mycorrhization resulted in 37% increase in root dry mass for beans, but no significant difference was observed for cucumbers. Results indicate the potential of root electrical capacitance measurements for monitoring the changes and differences of root water uptake rate.K e y w o r d s: mycorrhiza, phenology, root electrical capacitance, transpiration, water uptake INTRODUCTION

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Sensing the electrical properties of roots: A review

Ehosioke

Nguyen

Rao

et al. 2020

Vadose Zone Journal

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Thorough knowledge of root system functioning is essential to understand the feedback loops between plants, soil, and climate. In situ characterization of root systems is challenging due to the inaccessibility of roots and the complexity of root zone processes. Electrical methods have been proposed to overcome these difficulties. Electrical conduction and polarization occur in and around roots, but the mechanisms are not yet fully understood. We review the potential and limitations of low‐frequency electrical techniques for root zone investigation, discuss the mechanisms behind electrical conduction and polarization in the soil–root continuum, and address knowledge gaps. A range of electrical methods for root investigation is available. Reported methods using current injection in the plant stem to assess the extension of the root system lack robustness. Multi‐electrode measurements are increasingly used to quantify root zone processes through soil moisture changes. They often neglect the influence of root biomass on the electrical signal, probably because it is yet to be well understood. Recent research highlights the potential of frequency‐dependent impedance measurements. These methods target both surface and volumetric properties by activating and quantifying polarization mechanisms occurring at the root segment and cell scale at specific frequencies. The spectroscopic approach opens up a range of applications. Nevertheless, understanding electrical signatures at the field scale requires significant understanding of small‐scale polarization and conduction mechanisms. Improved mechanistic soil–root electrical models, validated with small‐scale electrical measurements on root systems, are necessary to make further progress in ramping up the precision and accuracy of multi‐electrode tomographic techniques for root zone investigation.

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Electrical capacitance of roots in relation to plant electrodes, measuring frequency and root media

Cited by 36 publications

References 10 publications

Role of phase angle measurement in electrical impedance spectroscopy

Role of phase angle measurement in electrical impedance spectroscopy

Simultaneous monitoring of electrical capacitance and water uptake activity of plant root system

Sensing the electrical properties of roots: A review

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