Chlorophyll fluorescent induction in plants treated with physiologically active compounds
Luminescent indices of photosynthesizing species depend on various biotic and abiotic factors and seem to be very attractive for monitoring the state of photosynthetic apparatus and for assessment of their functional activity. In this work, we have summarized the results of our experiments concerning the so-called slow fluorescence induction of the leaves. This fluorescence induction consists in a gradually decrease of the fluorescence intensity from maximal value FM to stationary value FT. It is supposed that this decrease is caused by some regulatory processes directed to the achievement of the optimal functioning of the light and dark stages of photosynthesis. In the experiments with bean plants treated with the inhibitor of electron transport diuron and also with specific activator of photosynthesis, we have established that the relative changes in (FM−FT)/FT ratio correspond to the relative changes in photosynthetic activity estimated as a rate of O2 evolution per chlorophyll. Further, in experiments with beans grown in aqueous solutions of heavy metals salts, we established an important and universal compensatory effect: a decrease in the chlorophyll content in plant leaves is accompanied by a corresponding increase in photosynthetic activity per chlorophyll. The paper presents data on the effect of physiologically active substances of various nature on the photosynthetic apparatus of various plants: herbicides, antioxidants, growth stimulants and other preparations used in practice. It has been shown, in particular, that a number of such preparations (Epin-Extra, Siliplant et al.) increase the resistance of the photosynthetic apparatus to stress factors.
Lomonosov Moscow State University, Faculty of Physics
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