Abstract
Exploration of electrical impedance measurements for imaging water transport in and around the roots of plants is described.
The scientific aim is to use the images to inform phenotyping in crop breeding programmes. The present work considers
preliminary measurements on a laboratory scale rhizotron fitted with 60 capacitively-coupled contactless conductivity (C4D)
electrodes in a rectangular array. This reduces electrochemical effects by including an insulating layer on the surface of the
electrodes. The resistance of the bulk material is deduced from spectroscopic considerations. Electrical impedance is
measured between pairs of electrodes to build up a two-dimensional map. A modified electrical model of the electrodes is
proposed which includes the resistive and reactive components of both the insulating layer and the bulk material. Using soil
as the bulk material the effect of water content, compaction and temperature are explored. Moisture has the strongest
influence particularly under dry conditions. Impedance measurements decrease by a factor of 1000 as soil moisture is
increased from 5% to 30%. Compaction, up to a pressure of 0.21 kg/cm2, changes the impedance by up to 20%, under dry
conditions. Measurements show a temperature sensitivity of about 2% / °C. Preliminary growth tests show changes in
impedance as a root system develops and are compared to a control test with no plant.
The scientific aim is to use the images to inform phenotyping in crop breeding programmes. The present work considers
preliminary measurements on a laboratory scale rhizotron fitted with 60 capacitively-coupled contactless conductivity (C4D)
electrodes in a rectangular array. This reduces electrochemical effects by including an insulating layer on the surface of the
electrodes. The resistance of the bulk material is deduced from spectroscopic considerations. Electrical impedance is
measured between pairs of electrodes to build up a two-dimensional map. A modified electrical model of the electrodes is
proposed which includes the resistive and reactive components of both the insulating layer and the bulk material. Using soil
as the bulk material the effect of water content, compaction and temperature are explored. Moisture has the strongest
influence particularly under dry conditions. Impedance measurements decrease by a factor of 1000 as soil moisture is
increased from 5% to 30%. Compaction, up to a pressure of 0.21 kg/cm2, changes the impedance by up to 20%, under dry
conditions. Measurements show a temperature sensitivity of about 2% / °C. Preliminary growth tests show changes in
impedance as a root system develops and are compared to a control test with no plant.
| Original language | English |
|---|---|
| Title of host publication | 7th World Congress on Industrial Process Tomography |
| Publisher | International Society for Industrial Process Tomography |
| Pages | 142-148 |
| Number of pages | 9 |
| ISBN (Print) | 978 0 853 16323 7 |
| Publication status | Published - Sep 2013 |
Keywords
- capacitively-coupled contactless conductivity
- ERT
- root zone monitoring