The Influence of Gibberellic Acid on the Growth andAlkaloid Biogenesis in Datzura stramonium Linné and in Atropa belladonna Linné

Abstract

Gibberellic acid in concentrations of 100 and 1,000 p. p. m. was administered as an aqueous spray to the leaves and tops of Datura stramonium and Atropa belladonna . Characteristic effects on the growth of the treated plants are described. Significant increases in plant height were demonstrated. The fifty-four-day-old stramonium plants were harvested four weeks after the first treatment. Fresh and dry weight data indicated increases in total, leaves and tops, and stem weights, but decreased root weight. The twelve-week-old belladonna plants were harvested seven weeks following treatment. Appreciable decreases in leaves and tops and root dry weights were noted. However, this was accompanied by significant increases in stem weight. Stramonium plants receiving both a single and double spray treatment with each concentration of gibberellic acid showed decreases in the concentration of total alkaloids in the leaves and tops and in the stems. Increased alkaloid roduction was observed in the roots. The favorable effects on growth from the two-spray treatment of 100 p. p. m. of gibberellic acid resulted in significant increases in total alkaloid production. Significant decreases in the concentration of alkaloids in the plant organs of belladonna were noted. Further, the total alkaloid content of belladonna treated with gibberellic acid was about one-half that of the untreated plants.