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 an d integrated intensity of delayed fluorescence (DF) in the time range 0.07-2.7 ms were studied in isolated thylakoids and leaves of Pisum sa tivum and Brassica napus. Amplitude of the 160 mus component of DF and lifetime of the ms-component and variable fluorescence in the thylako id suspension were changed only during the ID-phase of integrated DF i nduction that indicated reduction of the reaction centres of photosyst em 2 by the D-trough of the induction curve. In leaves a decrease of l ifetime of the ms-component of DF decay curve as well as of variable f luorescence close to initial levels were observed during the PS-phase of induction. The relative amplitude of the PS decline in induction cu rve in the thylakoid suspension was smaller than in leaves but similar to the amplitude of the ms-component of DF-decay curve at radiant ene rgy saturation of photosynthesis. The slow decline of integrated DF wa s sensitive to valinomycin, but not to nigericin. The study of combine d influence of irradiance and temperature on the DPS-phase of integrat ed DF measured simultaneously With CO2 fixation showed a higher correl ation between them when the dark delay before registration of DF was l onger. Hence the transition process of photosynthesis observed by the induction curve of integrated DF is in close connection with photosynt hetic dark reactions.