Sleeper occurrence after chilling in relation to depth of dormancy and bulb storage in Easter lily bulbs.

摘要

Experiments were carried out with cv. Hinomoto [Lilium longiflorum] to determine the relationship between depth of dormancy and sleeper occurrence after chilling, and also to determine factors involved in sleeper occurrence. Bulbs (19 to 22 cm in circumference), harvested from Okinoerabu Island, Japan, in June, were planted at different times of the season following dry storage at room temperature and sprouted at 10, 15, 20 or 25鳦 to determine the depth of dormancy. To determine sleeper occurrence, bulbs were vernalized at 9?for 6 weeks at different intervals after harvest and allowed to sprout at the prevailing summer temperatures (20-30? or at 25? Bulbs which were planted later in the season gave a higher percentage sprouting, and sprouted quickest at 15 and 20? This sprouting pattern indicated that the depth of dormancy decreased with increasing storage period at room temperature after harvest. A high percentage of bulbs sprouted if chilled immediately after harvest (90%). The sprouting percentage decreased markedly when bulbs were chilled after dry storage at room temperature for 2 weeks (50%). When the chilling was delayed further, the sprouting percentage improved (80-100%). Soaking bulbs in water at 47-48?for 1 h immediately after harvest accelerated sprouting at 20? dry-stored (for 1-2 weeks), chilled bulbs also had a high sprouting percentage following hot water treatment (90-100%). These results indicate that there is no relationship between depth of dormancy and sleeper occurrence and that dry storage of bulbs at 20-30?for 1-3 weeks after harvest in June induced the occurrence of sleepers after the vernalization treatment.