The electrical capacitance method was applied for the examination of living root systems in a pot experiment. The measured root capacitances gave an unambiguous indication of the development of root mass and length. The root capacitances measured using needle and clamp plant electrodes were closely similar when the roots of whole plants were placed in water, while increasing differences were observed with a decrease in soil water saturation. The difference in capacitance between the plant electrodes is outlined by interpreting the action mechanism of the clamp electrode. The capacitance and electrical impedance spectra (30 Hz-1 MHz) were determined for roots in soil, for pieces of roots washed free of soil, and for the soil itself. The root capacitance was smaller than that of the soil and higher than that of root pieces at 1 kHz, while the capacitance of the soil became equal to that of roots in soil at about 2 kHz. This calls attention to the importance of the measuring frequency when determining root capacitance. A capacitor model with two dielectric media is proposed besides Dalton's model in order to interpret the behaviour of root and soil capacitances. However, its validity requires further verification.
Preston, G. M., McBride, R. A., Bryan, J., Candido, M. (2004): Estimating root mass in young hybrid poplar trees using the electrical capacitance method. Agroforestry Systems, 60, 305-309.
'Estimating root mass in young hybrid poplar trees using the electrical capacitance method ' () 60 Agroforestry Systems : 305 -309 .
Soil Moisture Corp. (1990):Trase System 1 Operating Instructions.
Van Beem, J., Smith, M. E., Zobel, R. W. (1998): Estimating root mass in maize using a portable capacitance meter. Agron. J., 90, 566-570.
'Estimating root mass in maize using a portable capacitance meter ' () 90 Agron. : 566 -570 .
Webb, N. (ed.) (1989): Root length measurement with the Area Meter Mark 2 using computer software Root Version 3, Delta-T Devices Ltd.
Root length measurement with the Area Meter Mark 2 using computer software Root Version 3 , ().
Felföldi, J., László, P., Barabás, S., Farkas, J. (1993): Dielectric method for detection of irradiation treatment of potatoes. Radiat. Phys. Chem., 41, 471-480.
'Dielectric method for detection of irradiation treatment of potatoes ' () 41 Radiat. Phys. Chem. : 471 -480 .
Hayden, R. I., Moyse, C. A., Calder, F. W., Crawford, D. P., Fensom, D. S. (1969): Electrical impedance studies on potato and alfalfa tissue. J. Exp. Botany, 20, 177-200.
'Electrical impedance studies on potato and alfalfa tissue ' () 20 J. Exp. Botany : 177 -200 .
Hewitt, E. J. (1963): In F. C. Steward (ed.): Plant Physiology - A Treatise. Vol. VIII.
Plant Physiology - A Treatise , ().
Hilhorst, M. A. (1998): Dielectric characterisation of soil. Doctoral Thesis, Wageningen Agric. Univ., 141 p.
Andrén, O., Hanson, A.-C., Végh, K. R. (1993): Barley root growth and nutrient uptake from two soil types in rhizotron with vertical and horizontal minirhizotrons. Swedish J. Agric. Res., 23, 115-126.
'Barley root growth and nutrient uptake from two soil types in rhizotron with vertical and horizontal minirhizotrons ' () 23 Swedish J. Agric. Res. : 115 -126 .
Budó, é. (1972): Kísérleti fizika II. (Experimental Physics II) Nemzeti Tankönyvkiadó, Budapest. 395 p. (in Hungarian)
Chloupek, O. (1972): The relationship between electric capacitance and some other parameters of plant roots. Biologia Plantarum, 14, 227-230.
'The relationship between electric capacitance and some other parameters of plant roots ' () 14 Biologia Plantarum : 227 -230 .
Chloupek, O. (1977): Evaluation of the size of a plant's root system using its electrical capacitance. Plant and Soil, 48, 525-532.
'Evaluation of the size of a plant's root system using its electrical capacitance ' () 48 Plant and Soil : 525 -532 .
Chloupek, O. (1980): Wurzelsystemgröße und Produktivität der Luzerne. Z. Acker-Pflanzenbau, 149, 107-116.
'Wurzelsystemgröße und Produktivität der Luzerne ' () 149 Z. Acker-Pflanzenbau : 107 -116 .
Chloupek, O., Skácel, M., Ehrenbergova, J. (1999): Effect of divergent selection for root size in field-grown alfalfa. Can. J. Plant Sci., 79, 93-95.
'Effect of divergent selection for root size in field-grown alfalfa ' () 79 Can. J. Plant Sci. : 93 -95 .
Dalton, F. N. (1995): In-situ root extent measurements by electrical capacitance methods. Plant and Soil, 173, 157-165.
'In-situ root extent measurements by electrical capacitance methods ' () 173 Plant and Soil : 157 -165 .
Debye, P. (1929): Polar Molecules. Reinhold, New York.
Dukhin, S. S., Shilov, V. N. (1974): Dielectric Phenomena and the Double-Layer in Disperse Systems and Polyelectrolytes. John Wiley and Sons, New York.
Dielectric Phenomena and the Double-Layer in Disperse Systems and Polyelectrolytes , ().
Kendall, W. A., Pederson, G. A., Hill, R. R. (1982): Root size estimates of red clover and alfalfa based on electrical capacitance and root diameter measurements. Grass and Forage Science, 37, 253-256.
'Root size estimates of red clover and alfalfa based on electrical capacitance and root diameter measurements ' () 37 Grass and Forage Science : 253 -256 .
Matsumoto, N., Homma, T., Morita, S., Abe, J. (2001): Capacitance as a possible indicator for size of maize root system. Proc. of the 6th IRSS Symp. Nov 11-15, 2001. Nagoya, Japan, pp. 578-579.
Proc. of the 6th IRSS Symp. Nov 11-15, 2001. Nagoya, Japan , () 578 -579 .
Ozier-Lafontaine, H., Bajazet, T., Cabidoche, Y-M. (2001): Electrical capacitance as a tool for non-invasive root size estimation: Minimizing soil and electrodes influences. Proc. of the 6th IRSS Symp. Nov 11-15, 2001. Nagoya, Japan, pp. 190-191.
Proc. of the 6th IRSS Symp. Nov 11-15, 2001 , () 190 -191 .
Polomski, J., Kuhn, N. (2002): Root research methods pp. 295-321, In: Waisel, Y., Eshel, A., Kafkafi, U. (eds.), Plant Roots: The Hidden Half. 3rd edition. Marcel Dekker, New York, U.S.A.
Root research methods , () 295 -321 .