Effect of chilling and gibberellic acid on growth potential of excised embryos of Ruellia humilis

Summary Dormancy in intact seeds of Ruellia humilis is broken by chilling or by treatment with gibberellic acid (GA₃). Embryos are nondormant and will grow when the seed coat is removed completely. Embryos from chilled or GA₃-treated seeds have more growth potential than embryos from nontreated seeds. Dormancy is ascribed to the mechanical restriction of the embryo by the seed coat. Chilling and treatment with GA₃ break dormancy by increasing the expansive force of the embryo; thus, chilled or GA₃-treated embryos exert enough expansive force to break through the seed coat, whereas nontreated embryos do not.This work was supported by an NIH Biomedical Sciences Support Grant to the University of Kentucky.