Overcoming Dormancy in Lilium longiflorum Bulblets Produced in Tissue Culture1

Abstract

Leaf emergence from bulblets of Lilium longiflorum Thunb. generated in vitro from bulb-scale explants incubated in the dark at either 25 or 30°C was enhanced by 3 stimuli: incubation at 4°C for 1 or more weeks after removal from culture; immersion in water at 45° for 30 minutes to 8 hours after removal from culture; or in vitro red-light irradiation. For maximum response, bulblets generated at 25° required longer treatments at either 45° or under red-light irradiation. On the other hand, bulblets generated in vitro at 30° responded least to incubation at 4°. Although all 3 environmental factors ended dormancy, variation in rates of leaf emergence and total percentage of bulblets with leaves at the end of the experiments suggested differences in the state of bulblet dormancy due to in vitro temperature and differences in the physiological action of the environmental stimuli promoting leaf emergence.