Sleeper occurrence induced by dry storage followed by chilling in Easter lily bulbs

The present experiments examined factors involved in the sleeper occurrence of Easter lily (Lilium longiflorum) bulbs in relation to dry storage after harvest followed by chilling and then brought to room temperature. 'Hinomoto' bulbs, 15-19 cm in circumference which were harvested in Okinoer abu Island were stored dry at 9, 20 and 25 degrees C for two weeks and then chilled at 9 degrees C under a moist condition. The bulbs did not sprout a fter being moved to 20 degrees C; they became sleeper. The fresh weight of the dry-stored bulbs decreased to less than 85% of the their initial weight . A higher percentage of bulbs stored dry at 25 degrees C and followed by c hilling sprouted with increasing duration of storage at 25 degrees C than d id those bulbs dry - stored at 9 or 20 degrees C. After two weeks of dry storage, subjecting bulbs to 2 to 12 degrees C for 2 -3 weeks and then transferring them to 15 degrees C or higher induced them to become sleeper. In bulbs dry-stored at 25 degrees C for two weeks, leaf primordia different iated into scales when transferred to 20 degrees C after chilling at 9 degr ees C, whereas in bulbs kept moist at 25 degrees C for two weeks, they diff erentiated into foliage leaves during chilling. Soaking bulbs in 47-48 degrees C water for 1 hour after dry storage did not improve their sprouting percentage, whereas dipping the bulbs in hot water before dry storage promoted sprouting.