Regulation of Light Energy Distribution between Photosynthetic Pigment Systems; a Possible Role of Leaf Anatomy

The complex anatomical structure of an intact leaf results in a distribution of photosynthetically active energy between photosynthetic pigments which is different from that observed in isolated chloroplasts. The variance is due mainly to scattering at the gas-liquid interface between cells and intercellular space which tends to increase light absorption by the long wavelength absorbing pigments through secondary fluorescence. Evidence is given in support of an active use of this feature by the higher plant to regulate energy flow at the photophysical level of light absorption.