The effect of gibberellic acid on the dynamics of chlorophyll synthesis in etiolated seedlings

Chlorophyll formation in etiolated seedlings of wheat and maize, grown for 8 days on Knop's nutrient solution with 10μg. gibberellic acid (further GA) added per ml. was investigated and compared with control plants. Under the light of fluorescent tubes of an intensity of 3000 lux a significant decrease in the amount of chlorophyll (a+b) was observed at all time intervals from 0 to 24 hr., expressed both per dry weight and per leaf length. Experimental results indicate a decreased rate of chlorophyll formation in the presence of GA. At the same time, a lower content of carotenoids was found in etiolated plants than in controls grown in absence of GA. The colorimetric determination of the pigments was accompanied by paper chromatography which served as a control of quality and approximate amount of pigments.