1 Kutateladze Institute of
Thermophysics SB RAS, Russia 2 Siberian Federal
University, Russia 3 Siberian Institute of
Plant Physiology and Biochemistry, Siberian Division RAS, 664033
Irkutsk, Russia 4 Baikal Research Center, Irkutsk, Russia
*e-mail: f_const@mail.ru
Received October 30, 2010
The power of the internal heat source sufficient to
maintain a positive temperature of plants during one of the possible
form of cold stress - radiation frost was determined with the help of
numerical simulation.
The simulation of unsteady heat transfer in the soil-plant-air system
in the conditions of radiation frost showed that the the ground part of
plants is cooling most rapidly, and this process is partially slowed
down by the natural-convection heat transfer with warmer air. If the
frost is not continuous, the radiative cooling is the main danger for
plant. The necessary power of heat-production inside plant that allows
it to avoid hypothermia depends both on natural conditions and the size
of the plant. For plants with a typical diameter of the stem about 2 mm
this heat-production should be from 50 to 100 W / kg. Within 2 hours a
total amount of heat about 0.5 MJ / kg in the plant should be
allocated. Larger plants will have a smaller surface to mass ratio, and
the maintaining of it's temperature will require a lower cost of
nutrients per unit, accordingly.
Modeling of the influence of plant surface trichomes presence on the
process of its cooling showed that the role of trichomes in the
protection of plants from hypothermia during radiation frost usually is
negative due to the fact that the presence of trichomes increases the
radiative heat transfer from the plant and the impediment in air
movement near the plant reduces heat flux entering the plant from a
warmer air. But in cases where the intensity of heat generation within
the plant is sufficient for the maintenance of the plant temperature
higher than the air temperature, the presence of trichomes impairs heat
transfer from plant to air, and therefore contributes to a better
heating of plants.
