Dormancy in Dioscorea: Generality of gibberellin-induced dormancy in asexual dormant organs

Effects of GA₃ and CCC application on the sprouting of bulbilsor subterranean dormant organs of 10 species in the genus Dioscoreawere observed. Although the efficiency of both chemicals differedby species, in general GA₃ inhibited and CCC promoted the sproutingof the above dormant organs. In some species, however, dilutedGA₃ (0.003–0.3 µM) has a promotive and diluted CCC(3–30 µM) has an inhibitive effect on sprouting. Effects of GA₃ application on shoot elongation were tested onsprouted bulbils. GA₃ promoted elongation when applied directlyto the shoots and inhibited it when applied to the bulbous parts. These results suggest that GA activates two opposing reactions—sprouting-promotingand sprouting-inhibiting—in these organs. The complicatedrelation between GA₃ or CCC concentrations and sprouting wereexplainable by assuming that the two counteractive reactionswere activated by GA in different degrees. ¹ Present address: Department of Biology, Faculty of Science,Yamagata University, Yamagata 990, Japan. (Received June 21, 1976; )