Characteristics of current passage through plant tissue

Dvořák, Miroslav; Černohorská, Jana; Janáček, Karel

doi:10.1007/bf02895374

Cited by 18 publications

(8 citation statements)

References 7 publications

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“…In terms of an analogue electrical circuit, the present results clearly indicate a tree-root–soil continuum is a serial circuit with xylem and soil resistance over ruling the role of the contact resistance. In natural systems, a large array of interfering determinants for soil and xylem resistivity exists, such as soil texture and soil porosity (Chloupek, 1972; Samouëlian et al , 2005), root density (Amato et al , 2008, 2009; Zenone et al , 2008), soil and xylem temperature and solute concentration (Samouëlian et al , 2005), soil and xylem moisture (van Beem et al , 1998; Hagrey, 2007; Nadler and Tyree, 2008; Zenone et al , 2008), and cell anatomy and tissue integrity (Dvořák et al , 1981; Zhang and Willison, 1991, 1992; Zhang et al , 1993; van Beem et al , 1998; McBride et al , 2008). These factors vary considerably both in space and time.…”

Section: Discussionmentioning

confidence: 99%

“…Hence, the contribution of imaginary resistances arising from capacitor like cell structures (e.g. membranes) is considered as negligible ( Dvořák et al , 1981 ; Ozier-Lafontaine and Bajazet, 2005 ). In the present study, all measurements were performed using an earth tester (Fluke 1625, John Fluke, Everett, Washington, USA) operating at a peak voltage of 50 V AC and a low frequency of 111 Hz.…”

Section: Experimental and Theoretical Considerationsmentioning

confidence: 99%

“…Based on mathematically derived equations, the method was verified on allometric relationships (Čermák et al , 2006) and recently applied by Butler et al (2010). Basic assumptions, tacitly assumed to apply for the EIM, however, were not tested experimentally even though similar approaches clearly indicated extensive methodological limitations (Chloupek, 1972; Dvořák et al , 1981; Kendall et al , 1982; Dalton, 1995; Ozier-Lafontaine and Bajazet, 2005; Cao et al , 2010). …”

Section: Introductionmentioning

confidence: 99%

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Assessing the applicability of the earth impedance method for in situ studies of tree root systems

Urban

Bequet

Mainiero³

2011

Journal of Experimental Botany

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Several electrical methods have been introduced as non-invasive techniques to overcome the limited accessibility to root systems. Among them, the earth impedance method (EIM) represents the most recent development. Applying an electrical field between a cormus and the rooted soil, the EIM measures the absorptive root surface area (ARSA) from grounding resistance patterns. Allometric relationships suggested that this method was a valuable tool. Crucial assumptions for the applicability of the EIM, however, have not been tested experimentally. Focusing on tree root systems, the present study assesses the applicability of the EIM. Six hypotheses, deduced from the EIM approach, were tested in several experiments and the results were compared with conventional methods. None of the hypotheses could be verified and the results allow two major conclusions. First, in terms of an analogue electrical circuit, a tree-root–soil continuum appears as a serial circuit with xylem and soil resistance being the dominant components. Allometric variation in contact resistance, with the latter being the proxy for root surface area, are thus overruled by the spatial and seasonal variation of soil and xylem resistances. Second, in a tree-root–soil continuum, distal roots conduct only a negligible portion of the electric charge. Most of charge carriers leave the root system in the proximal parts of the root–soil interface.

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Section: Discussionmentioning

confidence: 99%

Section: Experimental and Theoretical Considerationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessing the applicability of the earth impedance method for in situ studies of tree root systems

Urban

Bequet

Mainiero³

2011

Journal of Experimental Botany

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“…The highest correlation was found for parallel capacitance at 1 kHz. Dvořák et al (1981) and Zhang et al (1995) demonstrated a positive relationship between the area of plant membranes and their electrical capacity in a plant-soil system. In measurements of electrical capacity, Dalton (1995) suggested that roots form columnar capacitors, the epidermis forms external electrodes, and the xylem forms internal electrodes that are analogous to the plates of a capacitor.…”

Section: Applicationmentioning

confidence: 96%

Improved wheat grain yield by a new method of root selection

Heřmanská¹,

Středa

Chloupek

2014

Agron. Sustain. Dev.

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International audienceWheat is a major source of protein for human food, a critical issue at a time when mankind is growing by 77 million people per year. Wheat was domesticated approximately 10,000 years ago and has been systematically bred for about 200 years. However, this breeding selection has been done using only aerial plant parts. Indeed, wheat roots, the hidden half of plant, were not considered in breeding programs due to the lack of an appropriate method. Here, we evaluated roots of 18 wheat populations. The root system size was measured by its electrical capacitance directly in field. The plants in third and fourth generations were evaluated during shooting and heading. Then plants were selected for large and small root system. In dry conditions, progeny of plants with large and small root system had yields of 17.1 and 10.9 g per plant in the third generation and 18.5 and 10.0 g per plant in the fourth generation. Our results show that the progeny of the plants selected for large roots have larger roots than their parents, also in next generation. Similarly, the progeny of small root plants have smaller roots. The selection process showed a greater response for larger root system size. This response can be evolutionarily advantageous and make selection easier than, for example, selection for grain yield. Our unique method enables accurate, repeated evaluation and harvest of selected plants. Selection for higher wheat root system size can be easily used to breed for drought tolerance and higher efficiency of water and fertilizer use

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“…Correlations of varying strength have been found between measured capacitances and root (dry) mass, root surface, and various attributes associated with physiological processes such as root development. For example, Ellis et al (2013) used an improved measurement setup to investigate the relation of electrical capacitances to root mass, root surface area, and root length in soil experiments. For an overview of studies using electrical capacitance measurements on root systems, we refer the reader to Kormanek et al (2015).…”

Section: Introductionmentioning

confidence: 99%

Multi-frequency electrical impedance tomography as a non-invasive tool to characterize and monitor crop root systems

Weigand

Kemna

2017

Biogeosciences

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Abstract. A better understanding of root–soil interactions and associated processes is essential in achieving progress in crop breeding and management, prompting the need for high-resolution and non-destructive characterization methods. To date, such methods are still lacking or restricted by technical constraints, in particular the charactization and monitoring of root growth and function in the field. A promising technique in this respect is electrical impedance tomography (EIT), which utilizes low-frequency (< 1 kHz)- electrical conduction- and polarization properties in an imaging framework. It is well established that cells and cell clusters exhibit an electrical polarization response in alternating electric-current fields due to electrical double layers which form at cell membranes. This double layer is directly related to the electrical surface properties of the membrane, which in turn are influenced by nutrient dynamics (fluxes and concentrations on both sides of the membranes). Therefore, it can be assumed that the electrical polarization properties of roots are inherently related to ion uptake and translocation processes in the root systems. We hereby propose broadband (mHz to hundreds of Hz) multi-frequency EIT as a non-invasive methodological approach for the monitoring and physiological, i.e., functional, characterization of crop root systems. The approach combines the spatial-resolution capability of an imaging method with the diagnostic potential of electrical-impedance spectroscopy. The capability of multi-frequency EIT to characterize and monitor crop root systems was investigated in a rhizotron laboratory experiment, in which the root system of oilseed plants was monitored in a water–filled rhizotron, that is, in a nutrient-deprived environment. We found a low-frequency polarization response of the root system, which enabled the successful delineation of its spatial extension. The magnitude of the overall polarization response decreased along with the physiological decay of the root system due to the stress situation. Spectral polarization parameters, as derived from a pixel-based Debye decomposition analysis of the multi-frequency imaging results, reveal systematic changes in the spatial and spectral electrical response of the root system. In particular, quantified mean relaxation times (of the order of 10 ms) indicate changes in the length scales on which the polarization processes took place in the root system, as a response to the prolonged induced stress situation. Our results demonstrate that broadband EIT is a capable, non-invasive method to image root system extension as well as to monitor changes associated with the root physiological processes. Given its applicability on both laboratory and field scales, our results suggest an enormous potential of the method for the structural and functional imaging of root systems for various applications. This particularly holds for the field scale, where corresponding methods are highly desired but to date are lacking.

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Characteristics of current passage through plant tissue

Cited by 18 publications

References 7 publications

Assessing the applicability of the earth impedance method for in situ studies of tree root systems

Assessing the applicability of the earth impedance method for in situ studies of tree root systems

Improved wheat grain yield by a new method of root selection

Multi-frequency electrical impedance tomography as a non-invasive tool to characterize and monitor crop root systems

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