1021-4437/03/5003- $25.00 © 2003
Russian Journal of Plant Physiology, Vol. 50, No. 3, 2003, pp. 407–410. Translated from Fiziologiya Rastenii, Vol. 50, No. 3, 2003, pp. 455–458.
Original Russian Text Copyright © 2003 by Loseva, Kashina, Rakhimova.
Plant has to adapt to variable environmental condi-
tions throughout its entire life. Thus, plant life can be
considered as continuous adaptation and all changes in
the plant can be regarded as adaptive responses .
Plant adaptive responses maintain a relative dynamic
stability of the internal environment and the function-
ing of every plant organ and system. Adaptation is a
process of changes in the plant structure and functions,
which provide for a better viability, vitality, and repro-
duction rate of an individual, population, and species
under changing environmental conditions. Each indi-
vidual plant and agrophytocenosis as a whole are open
dynamic systems, which continuously interact with
environment; hence, the increase in the potential of
plant adaptability throughout the entire growth period
is eventually a bioenergetic problem. In variable envi-
ronment, plants can have a high productivity and eco-
logical stability only under adequate energy supply .
To understand mechanisms of plant adaptation and
regulation of adaptive processes, one should have
objective tests for the assessment of the plant adaptive
potential. Integral characteristics, which reﬂect func-
tion of the whole plant organism, can provide an indi-
cator of sufﬁcient information content and sensitivity.
We think that the rate of heat production by plants,
which was shown to directly correlate with changes in
the anabolic and catabolic processes and reﬂect the efﬁ-
ciency of energy use [3, 4], can be used as such indica-
Every life phenomenon and every metabolic reac-
tion in their relationship with environment are associ-
ated with energy consumption (release). The resulting
manifestation of plant activity is its thermogram, which
was shown by Calve and Pratt to be “excellent numeri-
cal manifestation of the total functional activity” of the
living system .
The goal of this work is to assess the adaptation
potential of the plant cell under stress conditions (salin-
ization and elevated temperature) with the use of micro-
MATERIALS AND METHODS
Unicellular green alga (
) is a con-
venient organism for the study of various aspects of
plant cell activities. A homogenous culture of the alga
was grown in cultivation vessels in Tamiya medium
O, and FeSO
 at 30
C and bubbling with air containing 3% CO
The illuminance was equal to 10 klx at the vessel sur-
face facing daylight lamps.
Salinization was created by adding NaCl into exper-
imental vessels to the ﬁnal concentrations of 75, 150,
450, 500, and 550 mM. After 2 h, samples were taken
and the heat production rate was measured for 5 h. The
inﬂuence of elevated temperatures on the heat produc-
tion rate in algal suspension was measured in a calori-
metric cell at 45
C also for 5 h.
To assess the aftereffect of elevated temperature on
the adaptation potential of the plant cell, the algal sus-
pension was kept for 1 h for 45
C and, then, the suspen-
sion was transferred to the optimum conditions (30
and the heat production rate was measured.
Heat Production Rate as an Indicator of the Ability
of Plant Cell to Adapt to Environmental Conditions
N. L. Loseva*, O. A. Kashina**, and G. G. Rakhimova*
*Kazan Institute of Biochemistry and Biophysics, Kazan Research Center, Russian Academy of Sciences
**Biological and Soil Faculty, Kazan State University, Kremlevskaya ul. 18, Kazan, 420008 Russia;
Received May 5, 2001
—The heat production rate in the suspension of unicellular alga (
) was studied by
the method of microcalorimetry during adaptation of the alga to stress conditions (NaCl and 45
C). The heat
production rate slightly increased after the addition of 75 mM NaCl to cell suspension. A two-phase response
was observed at 150 and 450 mM NaCl and at elevated temperature. The heat production rate was high during
the ﬁrst 3–4 h; then, it decreased and leveled off. This characteristic dramatically decreased at a high salt con-
centration (500 mM). Cell was unable to adapt to a high NaCl concentration (550 mM), which led to energy
dissipation manifested in a high heat production rate. We conclude that the heat production rate, an integral indi-
cator of plant cell activity can be used to assess plant cell adaptation to the impact of stress factors.
Key words: Chlorella vulgaris - heat production - salinization - extreme temperature - adaptation