MODEL STUDIES OF CHLOROPHYLL FLUORESCENCE REABSORPTION AT CHLOROPLASTLEVEL UNDER DIFFERENT EXCITING CONDITIONS

A theoretical model is presented describing the distortion of chloroph yll fluorescence spectra of a chloroplast or a group of chloroplasts b y the effect of fluorescence reabsorption. Model calculations using th e experimental data show that the primary reabsorption effect occurs a lready within one chloroplast and the spectral distortion depends sign ificantly on the excitation regime of the chloroplast. A theoretical d ependence of the distortion function, defined as a change in the F(685 )/F(735) fluorescence band ratio, on the mean chlorophyll concentratio n in a chloroplast is predicted for different light excitation regimes . The distortion of measured chlorophyll fluorescence spectra at 77 K of chloroplast suspension adsorbed on filter papers of two strongly di fferent diffusive reflectivities and at different mean chlorophyll con centrations are discussed with the help of the presented theory.