1021-4437/03/5005- $25.00 © 2003
Russian Journal of Plant Physiology, Vol. 50, No. 5, 2003, pp. 701–703. Translated from Fiziologiya Rastenii, Vol. 50, No. 5, 2003, pp. 781–784.
Original Russian Text Copyright © 2003 by Zhirenko.
Among various methods of studying water use in
plants, the methods based on determination of heat
transfer with the xylem sap ﬂow are considered most
informative. These methods allow accurate quantitative
monitoring of water consumption in its dynamics by
means of multiple and continuous observations over
long periods. These methods cause no substantial dam-
age to the plants tested.
The thermal methods are classiﬁed into two types,
depending on the use of pulsed or continuous heating.
In the heat pulse method, the time is recorded during
which the heat pulse produced by a heating element
travels with a xylem sap ﬂow to a certain distance. A
drawback of this method is that individual measure-
ments are separated by discrete times of at least 25–
30 min. These periods are required for the recovery of
the initial heat balance in a plant under study, as a pre-
condition for a replicate measurement. Furthermore,
owing to speciﬁc features of this method, the applica-
tion of automated systems for data recording is strongly
complicated [1, 2].
The method of constant heating is based on monitor-
ing the amount of heat removed with the xylem sap ﬂow
during continuous heat production by a heating element.
This method is readily compatible with automated sys-
tems for data acquisition and allows for continuous mea-
surements over periods of any duration. Studies of water
use in plants, based on the constant heating method,
involved a large variety of measurement systems [3–7].
A disadvantage of such systems is a considerable con-
sumption of electric power, which restricts their applica-
tion in the areas remote from electric power lines. The
use of transportable electric power stations for power
supply of such systems is quite expensive.
Devising of an inexpensive, transportable and easily
operated recording system with an autonomous power
supply, providing for continuous monitoring of data
over prolonged periods, becomes an urgent task. Solv-
ing this task would promote investigations of water use
in plants in their natural environments.
This work describes an original designed autono-
mous measurement system, based on the continuous
heating method, that was employed for determining
and recording of water consumption in plants.
DESIGN AND PRINCIPLE OF SYSTEM
Figure 1 displays the block diagram of the instru-
ment. The measuring system is based on a commer-
cially available potentiometric recorder (PO Lvovpri-
bor, Ukraine). When the tracing detector system is
under equilibrium conditions, the electric power con-
sumption by the recorder does not exceed 22 W. The
closed and robust case of this instrument makes it suit-
able for the use in ﬁeld conditions. Because of its tech-
nical characteristics, design, and low price, this poten-
tiometric recorder is suitable for devising a measuring
system supplied with energy from an autonomous
An autonomous dc power source (24 V) is conve-
nient for this purpose, because the RP160-17 recorder
is assembled from low-voltage components. This dc
voltage was fed directly to the power-supplying block
of the recorder, passing over the power transformer and
the diode bridge rectiﬁer, because these blocks are only
Autonomous System for Measuring Water Consumption
N. G. Zhirenko
Institute of Forestry, Russian Academy of Sciences, Uspenskoe, Moscow oblast;
Tellerman Experimental Forestry, Institute of Forestry, Russian Academy of Sciences,
POB 14, Borisoglebsk, Voronezh oblast, 397140 Russia
fax: 7 (07354) 6-2601; e-mail: firstname.lastname@example.org
Received December 4, 2002
—An autonomous system based on a constant heating method and designed for measuring water con-
sumption in plants is described. The system was built into an industrially produced potentiometric recorder; it
contained two input channels and operated with thermoelectric temperature sensors. The system operation was
tested in experiments on mature trees of pedunculate oak (
Key words: Quercus robur - water consumption - methods
: thermo-emf—electromotive force arising in the
electrical circuit composed of dissimilar metallic conductors with
their junctions exposed to different temperatures.