The relation between light and temperature effects in the induction and release of dormancy in the aerial tuber of Begonia evansiana

The effect of light quality on the induction and release ofbud dormancy in aerial tubers of Begonia evansiana ANDR. andthe relation in controlling the mechanism of dormancy betweenlight and temperature were investigated using aerial tubersin different dormant states; immature tubers which were sproutedby irradiation and mature ones which were sprouted only afterchilling. Blue or far-red light induced photo-sprouting in immature tubersat higher temperatures and also promoted release of dormancyin mature tubers caused by chilling (2–5°C). Blueor far-red light, however, failed to break mature tuber dormancyat room temperature. The induction of dormancy in immature tubers was advanced atlow temperatures (15–17°C) which were inoperativefor photo-sprouting. Lower temperatures showed conflicting dualeffects of inducing and breaking dormancy. Red light inhibitednot only photo-sprouting in immature tubers but also dormancyrelease in mature tubers at low temperatures. These light- and temperature-dependent reactions are independentlyinvolved in dormancy regulation, the former is overcome by thelatter with dormancy development. (Received December 3, 1968; )