The Role of Gibberellin, Abscisic Acid, and Auxin in the Regulation of Developing Wheat Grains

Three forms of inhibition of germination of developing wheat grains are described. One, due to the outer pericarp, may not involve growth substances. The others occur in the embryo itself and are due also to the other grain tissues surrounding the embryo. Experiments with applied growth substances suggest that these may be regulated by a balance of endogenous gibberellins and abscisic acid, but the results of extraction experiments show limited correlation with germination experiments, and indicate that auxin may also be inhibitory.