%0 Research article
%T Measurement of the tree root growth using electrical impedance spectroscopy
%A Repo, Tapani
%A Laukkanen, Janne
%A Silvennoinen, Raimo
%D 2005
%J Silva Fennica
%V 39
%N 2
%R doi:10.14214/sf.380
%U https://silvafennica.fi/article/380
%X 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).