Emerson Enhancement Effect in Chloroplast Reactions

The discovery of the Emierson enhancement effect in photosynthesis (3-6, 8) led to the suggestion that there are 2 photochemical reactions necessary for conmplete photosynthesis. A likely hypothesis is that the 2 reactions are carried on by different forms of chlorophyll a (10, 11). The enhancement effect in photosynthesis has been studied extensively in several laboratories (19) and it has been shown (12,14, 15) that the effect also occurs in 02 evolution in the Hill reaction using quinone as the electron acceptor. G7ovindjee et al. (13) have recently reported the existence of the Emerson enhancement effect in NADP photoreduction by spinach chloroplasts using white (fluorescent) supplementary light. This paper deals with observations on the enhancement of NADP l)hotore(luction anld 02 evolution in chloroplast preparations, using both white and nmonochromatic lights.