THE RELATION OF LIGHT-INDUCED-CHANGES OF CHLOROPHYLL DELAYED FLUORESCENCE AND CO2 FIXATION OF PLANTS

Light-induced changes of the exponential components of decay curves and integrated intensity of delayed fluorescence (DF) in the time range 0.07-2.7 ms were studied in isolated thylakoids and leaves of Pisum sativum and Brassica napus. Amplitude of the 160 mus component of DF and lifetime of the ms-component and variable fluorescence in the thylakoid suspension were changed only during the ID-phase of integrated DF induction that indicated reduction of the reaction centres of photosystem 2 by the D-trough of the induction curve. In leaves a decrease of lifetime of the ms-component of DF decay curve as well as of variable fluorescence close to initial levels were observed during the PS-phase of induction. The relative amplitude of the PS decline in induction curve in the thylakoid suspension was smaller than in leaves but similar to the amplitude of the ms-component of DF-decay curve at radiant energy saturation of photosynthesis. The slow decline of integrated DF was sensitive to valinomycin, but not to nigericin. The study of combined influence of irradiance and temperature on the DPS-phase of integrated DF measured simultaneously With CO2 fixation showed a higher correlation between them when the dark delay before registration of DF was longer. Hence the transition process of photosynthesis observed by the induction curve of integrated DF is in close connection with photosynthetic dark reactions.