Determination of optimum conditions for breaking bulb dormancy in relation to growth and flowering in Lilium hansonii

This study was conducted to determine the optimum low temperature treatment and the additive effect of soaking in hot water to overcome bulb dormancy of Hanson lily ‘Lilium hansonii’. To accomplish this, bulbs were refrigerated at 1, 4, and 7°C for 35, 50, and 65 days, respectively. As the control treatment, the bulbs were planted directly without any cold or hot water treatment. After the treatments, the bulbs were planted in pots filled with sterilized commercial soil mixture and vermiculite at a depth of about 5–10 cm in a greenhouse. The days to emergence, percentage of emergence, plant height (cm), number of leaves, number of flowers, and days to flowering were recorded. Bulbs soaked in hot water (45°C) for 1 hour and stored at 4°C for 65 days showed the earliest emergence and the maximum emergence percentage. Moreover, storage at 4°C for 65 days (without hot water treatment) was found to promote stalk elongation and a higher number of leaves than the hot water treated bulbs. Results indicated that hot water treatment had a significant additive effect on breaking bulb dormancy in L. hansonii, particularly with respect to days to emergence. Hot water pre-treatment also equilibrated the internal conditions of the bulbs, which resulted in the uniformity of the physiological state of the bulb.