Tapani Repo , Janne Laukkanen, Raimo Silvennoinen

Measurement of the tree root growth using electrical impedance spectroscopy

Repo T., Laukkanen J., Silvennoinen R. (2005). Measurement of the tree root growth using electrical impedance spectroscopy. Silva Fennica vol. 39 no. 2 article id 380. https://doi.org/10.14214/sf.380

Abstract

The non-destructive evaluation of plant root growth is a challenge in root research. In the present study we aimed to develop electrical impedance spectroscopy (EIS) for that purpose. Willows (Salix myrsinifolia Salisb.) were grown from cuttings in a hydroponic culture in a growth chamber. Root growth was monitored at regular intervals by a displacement method and compared with the EIS parameters of the plants. To measure its impedance spectrum (IS) (frequency range from 40 Hz to 340 kHz) each plant was set in a measuring cell filled with a solution of the hydroponic culture. The IS was measured using a two-electrode measuring system. A silver needle electrode was connected to the stem immediately above the immersion level and a platinum wire was placed in the solution. The measurements were repeated twice weekly for a root growth period of one month. The IS of the entity consisting of a piece of stem, roots and culture solution were modelled by means of an electric circuit consisting of two ZARC-Cole elements, one constant-phase element, and a resistor. On the plant basis, an increase in root volume by growth correlated with a reduction in the sum of resistances in the ZARC-Cole elements (mean Pearson’s correlation coefficient r = –0.70).

Keywords
willow; CNLS-curve fitting; displacement method; distributed electric model; hydroponics; impedance analysis

Received 28 October 2004 Accepted 17 March 2005 Published 31 December 2005

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