1021-4437/03/5002- $25.00 © 2003
Russian Journal of Plant Physiology, Vol. 50, No. 2, 2003, pp. 247–250. Translated from Fiziologiya Rastenii, Vol. 50, No. 2, 2003, pp. 275–279.
Original Russian Text Copyright © 2003 by Farkhutdinov, Veselova, Veselov, Mitrichenko, Dedov, Kudoyarova.
In nature, ambient temperature varies constantly
because of changing cloudiness, gusts of wind, etc.
Under these conditions, the plant capacity of a rapid
responding to environmental changes acquires a great
importance. A temperature-enhanced transpiration cre-
ates a misbalance between water inﬂux from roots and
its loss by leaves, which can suppress growth and
induce other unfavorable consequences [1, 2]. There-
fore, it was of interest to elucidate the mechanisms of
plant adaptation to a rapid temperature increase.
The plant is well known to reduce the water loss by
stomata closure [3, 4]. However, the mechanism oper-
ates frequently that prevents stomata closure after a
temperature rise . This mechanism evidently pro-
vides for plant cooling due transpiration and maintains
gas exchange required for photosynthesis. Earlier,
using a highly sensitive linear displacement transducer,
we followed the effect of temperature lowering in the
nutrient medium on wheat seedling growth . Here,
using this advice, we attempted to monitor leaf growth
responses to increased air temperature.
Cell elongation is known to depend not only on
water availability but also on water demand from grow-
ing cells, which, in particular, is determined by the state
of the cell walls and their extensibility [2, 7]. Therefore,
in this work, we juxtaposed growth responses and leaf
The objective of this work was to follow a rapid
growth response of wheat plants to an increase in tem-
perature and to reveal the mechanisms maintaining
growth under these conditions.
MATERIALS AND METHODS
Experiments were performed on durum spring
L., cv. Bezenchukskaya 139)
seedlings under laboratory conditions. Seeds were ger-
minated in darkness at 24
C on 5
tilled water. Three-day-old seedlings were transferred
to 10% Hoagland–Arnon nutrient medium and grown
under an illuminance of 18 klx and 14-h photoperiod.
During the light period, air temperature was 20–24
Eight-day-old seedlings were subjected to heating by a
rapid (during several minutes) increase in air tempera-
ture by 4
C using a ﬂow of hot air from a heating
ventilator. This temperature was maintained for 1.5 h.
In some experiments, 15 min before heating, HgCl
was added to the nutrient solution to the ﬁnal concen-
tration of 50
M. After 5 min, the solution was replaced
by the initial one. Transpiration was estimated as the
loss of water for 10 min by weighing the glass with ten
seedlings placed in 50 ml of the nutrient solution. The
glass was covered with foil with holes for seedlings in
order to prevent water evaporation from the solution
Plant growth was recorded using a growth sensor 
constructed on the basis of the DLT-2 linear displace-
The Effect of Rapid Temperature Increase
on the Growth Rate of Wheat Leaves
R. G. Farkhutdinov, S. V. Veselova, D. S. Veselov, A. N. Mitrichenko,
A. V. Dedov, and G. R. Kudoyarova
Institute of Biology, Ufa Research Center, Russian Academy of Sciences, pr. Oktyabrya 69, Ufa, Bashkortostan, 450054 Russia;
Received May 17, 2001
—The growth rate of the ﬁrst leaf of eight-day-old wheat plants was measured using a DLT-2 highly
sensitive linear displacement transducer. Leaf extensibility was evaluated from the growth rate under the
increase in the pulling force by 2 g. An increase in the air temperature resulted in the doubling of the transpira-
tion rate and immediate slowing of the leaf growth followed by the leaf shrinkage. However, growth was later
resumed almost completely. Heat treatment did not induce any changes in the leaf extensibility, indicating that
cell-wall mechanical properties were not changed. Growth retardation was supposed to result from a decrease
in the water content in the leaf tissues because the balance between water inﬂux from roots and its loss through
transpiration was shifted toward the water loss. An initial drop in the relative water content (RWC) indicates
such a misbalance. Subsequent growth resumption coincided with a decreased water deﬁciency. Since the rate
of transpiration was not reduced, RWC and growth rate restoring evidently occurred due to the activated water
uptake by roots, which can be explained by the increased hydraulic permeability detected in our experiments.
Key words: Triticum aestivum - growth rate - transpiration - increased temperature
: RWC—relative water content.