Evaluation System Of Lily Cold Tolerance And Selection Of Cold Tolerant Lily Cultivars

The consumption of lily,important business flower,has seasonal characteristics in China,and it has a huge demand especially during the "Lunar New Year" period.The price is usually several times as the usual,so the winter and spring are the planting period of a large number of the lily.In this period,the temperature is low and most commercial lily cultivars are not cold tolerant,for which the lily cultivation is usually carried out under the conditions of the facility.In order to improve the quality of lily cut flowers,producers need to employ artificial heating based on changes in temperature and lily growth and development.However,manual heating not only consumes a lot of energy and causes environmental pollution,but also significantly increases production costs.Therefore,the breeding of cold tolerant lily cultivars has important ecological and economic value in winter and spring cultivation.In this paper,the cold resistance of 30 commercial lily cultivars was evaluated using low temperature cycling equipment,and the evaluation system of cold resistance of lily was established.On the basis,four cultivars,‘Conca D'or',‘Merlet',‘Sheila'and‘Terrasol'were treated by cold temperature and the effects of starch,soluble sugar,proline,malondialdehyde(MDA)and the relative electrical conductivity of leaves were studied,which aims to reveal the mechanism of cold tolerance of four cultivars from cell and physiology.The experimental results were as follows:(1)Logistic curves of thirty cultivars presented obvious S,the significance of Rata was in the level of 0.05 or 0.01,and the LT50 of these experimental materials were between-5? and-9?.But some cultivars with strong cold resistance can be found,such as‘Conca D'or',‘Metropolitan',‘Forever'and‘Carmine Diamond',and cold sensitive cultivars were‘Terrasol',‘Castellani',‘Yelloween'and‘Donato'.The results showed that the cold resistance of commercial lily varieties on the market was weak and the proportion of cultivars with strong cold resistance was very small.(2)Compared with the control,the starch content in the leaf of the four lily varieties,‘Conca D'or',‘Merlet',‘Sheila'and‘Terrasol'decreased by 64%,72%,79%and 73%respectively after 5-day low temperature treatment;the contents of soluble sugar increased by 28%,34%,36%and 24%respectively;MDA contents increased 147%,184%,247%and 90%respectively,and relative electrical conductivity increased 56%,65%,104%and 191%respectively.In addition,the electron microscopy showed that the starch grains in the chloroplasts of the four lily varieties had different degrees of degradation during the low temperature treatment.The results showed that the changes of proline content and EC were closely related to the cold tolerance of lily,and it was an important physiological index to evaluate the cold resistance of lily.The contents of starch,soluble sugar and MDA didn't reveal it well and were not suitable as a cold evaluation index of lily.