Studies On Chilling Requirement Of Lily Bulbs In Dormancy

Lily is a kind of famous flower. The bulb has the characteristic of endordormancy. Breaking of the dormancy need a certain low temperature accumulation. This is the important point in the technique of bulb harvest. In this study, we use Navona, Prato, Sobon, Siberia as materials to study the chilling requirement of lily bulbs. The key results as follow: 1. Observing the germination of lily bulbs during different low temperature treatment, we found: the sprouting time and the treatment days has the remarkable minus correlation; it has the notable positive correlation among the germination rate, the low temperature treatment time and the planting days; the germination uniformity of a lot would increase if we prolong the treatment day. 2. Studding the growth of lily after low temperature treatment. We found the treatment time is longer; the vigorous of lily is better. 3. 5℃is the best effective temperature for breaking of the lily bulb dormancy. It's no effect, if temperature is above15℃. There is only Navona lily bulb has the effect after -2℃treatment. About 0℃and 10℃, there are different results among the different lily cultivars. Navona and Siberia: the effect of dormancy broken at 0℃is higher than it is at 10℃, Sobon: The result is just opposite. 4. The chilling requirement of the four lily bulbs as follow: Lilium Asiatic hybrids need 30 days low temperature treatment at least, but for Lilium Oriental hybrids, we must exposure them to low temperature above 90 days. If we use chilling unit ,then the results are Navon,1200C﹒U; Prato,840C﹒U; Sobon,2280C﹒U;Siberia,2160C﹒U. 5. There are four indexes to determine the complete of chilling requirement. These are spouting time, germination rate, germination uniformity of a lot, and vigorous. That is to say, if the bulb has better generation rate in short time and better growth, then the bulb complete the chilling requirement for dormancy broken. 6. Studding the reducing sugar content and CAT activity in lily bulb during low temperature treatment, we found: the rapid increasing of reducing sugar content can accelerate lily bulb dormancy broken. With the development of the treatment, the activity of CAT in Lilium Asiatic hybrids decline. So it looks like no effect between CAT activity and dormancy broken. But in Lilium Oriental hybrids, we found there are a certain correlation between the rise of CAT activity and the breaking of lily bulb dormancy.