Relationships Between Time Course, Chromatic Transient, and Enhancement Phenomena of Photosynthesis

Abstract

Possible relationships were sought between the wavelength dependent phenomena of time course, chromatic transients, and the Emerson effect of enhancement. Rate of O2 evolution was measured as the current from a polarized platinum electrode covered by a thin layer of Chlorella. Illumination was provided by 1 or both of 2 monochromatic light beams at 650 and 700 mu. It was possible to demonstrate a close relationship between the chromatic transients and time course phenomena. Good approximation to the transients could be constructed from the rise and decay curves in rate of O2 evolution observed under appropriate conditions. By decreasing the period of alternation of the 2 light beams an orderly progression could be demonstrated between the chromatic transients of Blinks and the Emerson effect of enhancement. When the 2 light beams were alternated at short periods (0.6 seconds) the relative magnitude of enhancement was equal to that observed when the 2 beams were presented continuously. The observations are interpreted as demonstrating a specific reaction in photosynthesis associated with chlorophyll b (or other accessory pigment) and having time constants of the order of seconds.