Auxin Gibberellic Acid Interaction in Controlling the Hypocotyl Growth in Seedlings.

High concentrations of indole-3-butyric acid, when applied at a concentration of 100 to 200 parts per million (ppm) to presoaked seeds, cause a marked inhibition of hypocotyl length in the seedling growth of Phaseolus mungo var. T-2. Gibberellic acid, when applied at a concentration of 5 ppm, quantitatively reversed this inhibition. It is suggested that the interaction between these two growth substances controls the morphogenetic differentiation in regard to hypocotyl formation in seedling growth.