Action of Gibberellic Acid on Lettuce Seed Germination

Abstract

Several workers have shown that gibberellic acid (GA,) promlotes the germination of seeds whiclh or-dinarily require light (6, 10, 13, 14, 16, 17, 23, 28, 30). This phenomenon raises several fundamental ques-tions as to the mechanism of light-controlled germina-tion: A: Does light simply act by releasing a gib-berellin in the seed, B: Does the GA3 substitute for light by bringing about chemically a reaction which is normally photochemical, or C: Does the GA, bring about some quite other type of growth process which independently leads to germination? The following experimeints are an attempt to provide answers to these questions. MIATERIALS AND MIETHODS The seeds used for germination studies were those of Lactiuca sativa L. var. Grand Rapids (Breck's Co., Boston, -Mass.). For some of the gibberellin extrac-tion work the seeds were supplied by Pieters Wheeler Seed Co., Gilroy, Cal. Since germination in the dark w-as found to be gradually induced even in dry seeds, when stored at room temperature and humidity (cf.