Effect of Intermittent and Continuous Light on Chlorophyll Formation in Etiolated Plants

Short impulses of white light induce continuous synthesis of chlorophyll a and b in etiolated barley leaves. No lag phase is observed, and the rate of chlorophyll a accumulation is much higher than that of chlorophyll b, so that the a/b ratio is very high (12 to 20). The chlorophyll accumulation reaches a plateau at about 70 flashes after which the rate of their formation decreases appreciably. When the etiolated plants, after exposure to about 80 to 100 flashes, are transferred to continuous light, one can observe that the rate of formation of chlorophyll a and b increases during the first hour, and after that becomes still more rapid. At the same time the a/b ratio falls and it reaches a value of about 3 normally found in green leaves. Copyright © 1966, Wiley Blackwell. All rights reserved