[Fluorescent Indices of Bean Leaves Treated with Sodium Fluoride].

It is shown that the treatment of bean leaves with NaF in concentration of 10(-2) M resulted in the alteration of fluorescent indices registered by the method of pulse fluorimetry. Fluorescent parameters F(0) and F(m) decreased, but the ratio F(v)/F(m) = (F(m) - F(0))/F(m), characterizing the maximal photochemical activity of photosystem II remained invariable. Photochemical fluorescence quenching (qP) was higher than in control during the first minutes of illumination with the actinic light, and it markedly decreased with the following illumination. Nonphotochemical quenching (qN), in contrary, decreased at the beginning of illumination, and then increased. Photosynthetic activity as characterizing by the ratio (F(M) - F(T))/F(T) reduced after the leaf treatment with NaF. Results obtained are interpreted proceeding, on the one hand, from the influence of NaF on redistribution of excitation energy between photosystem II and photosystem I and its inhibitory effect on the ATPase complex and Kalvin-Benson cycle, on the other.