Thermostability of plants in various light conditions of cultivation

At various levels of PHAR with the help of measurement of parameters of a slow induction of chlorophyll fluorescence at 682 and 734 nm in light culture conditions the thermostable estimation of cenosises of plants of wheat and radish in reply to action of the raise and damaging temperatures of air (35degreesC 20 hours, 45degreesC 7 hours) is carried out. Without dependence from a level of light exposure, the exposition of cenosises at 35degreesC did not result in irreversible changes of the photosynthetic device of plants. The minimal damage of cenosises of wheat and radish at influence of temperature 45degreesC observed at 150 W/m(2) of PHAR, and maximal - at intensities, close to a level of a compensatory point of photosynthesis of cenosises (50-70 W/m(2) PHAR at temperature of air 24degreesC). The index of viability is most sensitive parameter in comparison with other parameters determined by a method of a slow induction of fluorescence at 682 and 734 nm. The character of its change in reply to action of the stress-factor coincides with change of intensity of photosynthesis researched of cenosises.