MECHANISMS OF NONPHOTOCHEMICAL CHLOROPHYLL FLUORESCENCE QUENCHING IN HIGHER-PLANTS

The excitation energy of pigment molecules in photosynthetic antennae systems is utilised by photochemistry, partly it is thermally dissipat ed, and partly it is emitted as fluorescence. Changes in the quantum y ield of chlorophyll (Chl) fluorescence reflect the changes in quantum yield of photochemical reaction and thermal dissipation of the excitat ion energy. Decrease of the Chl fluorescence quantum yield is called t he Chl fluorescence quenching. The decrease of the quantum yield that is accompanied by photochemical reactions has been termed the photoche mical quenching, and the decrease accompanied by thermal dissipation o f the excitation energy is called the non-photochemical quenching. Thi s review deals with mechanisms of the nonphotochemical quenching.