Basic Research Of Tree Peony Cut Flowers Under Large-scale Storage

Being deciduous subshrub belonging to the genus Paeonia L, family Paeoniaceae,tree peony (Peaonia suffruticosa Andr), which has been planted for over two thousandyears in China, is one of the traditional famous flowers and the candidate nationalflower of China which are widely used in gardening. At present, tree peony cut flowersare high-end floral materials in domestic and foreign markets which are sold in largequantities every year. The blossom period of tree peony is concentrated in seasonalApril, at the same time the flowering period of one single flower is short.Consequently, the research on large-scale storage technology of tree peony cut floweris particularly important. In this thesis, cut flowers of tree peony cv.‘Xiangyu’ indifferent developmental stages and different storage phases being experimentalmaterials, the cold resistance of floral organs and the metabolism of water, ethyleneand respiration of cut flowers being stored in cold temperature, and the petal protease,the change of nuclease activity and essential oils during petal senescence were studied,which will explore the physiological and biochemical changes in the process ofsenescence so as to provide a theoretical basis and practical basis to extend the storageperiod and the vase life of tree peony cut flowers. The results are showed as follows.1. The supercooling point of seven floral organs of tree peony cv.‘Xiangyu’ reachto-11.6°C to-12.0°C, and the highest temperatures of the freezing point are allbetween-4.7°C to-5.9°C. With the flowering process goes on, the cold resistanceability gradually weakened, which have the ability to resist low temperature at-5°C.So tree peony cut flowers are suitable to be stored under the conditions of lowtemperature at-5°C~0°C, without any damage on the cut flower.2. After pretreatment, with the extension of the storage time, the flowering rate,the vase life and the days from period stored in vase to the full blossom stage of treepeony cut flowers which are stored at low temperature all decline. With the high water absorption capacity, the flowering rate of tree peony cut flower which are stored at lowtemperature for50days is enough high, which has high ornamental value. Therefore, itis safe and feasible for tree peony cut flowers to store at low temperature such as-2.5±1°C. The vase life of tree peony cut flower is closely related with water balance value.The treatment of STS on tree peony can significantly extend the vase life which canantagonize the senescence.3. Tree peony cv.‘Xiangyu’’ is ethylene sensitive and climacteric. During floweropening and senescence process, the ethylene production rate and the respiration ratein petal are rising, and the content of ACC are also increasing which showed that thepetal senescence are closely related with the ethylene production. With the extensionof the storage time, the ethylene production in petals declined gradually, and the ACCcontents gradually inclined. So it is predicted that the pathway of ACC conversion toethylene probably be blocked during the storage process of tree peony cut flower,resulting in ACC concentrated in cut flowers in quantities and the sharp drop inethylene production.4. With the opening of tree peony flowers, the protein content in petal graduallyinclines. It is relatively high during the open-top stage, the initial flowering stage andthe half flowering stage. However, it declines significantly during the full-floweringstage, and it reaches the minimum point during the initial decay stage. With thedevelopment stage goes on, the protease activity in petals gradually increased and itrapidly increases from the full-flowering stage to the initial decay stage. For sameopening stage, the protein content in flowers which are irrigated before blossom issignificantly higher than controls, and the extent of the protein decline is quite slowerthan control. The change of DNA content in petals and the DNase activity was nothigh. The RNA contents decrease significantly due to the rapid increase of RNaseactivity. Irrigation before flowering can inhibit the nuclease activity, reducing the rateof nucleic acid degradation, delaying plant senescence. Therefore, we should choosethe flowers at open-top stage (II level) to be stored and irrigation before floweringbenefit the safe storage of cut flower.5. The essential oils in flowers of tree peony cv.‘Xiangyu’ are mainly alcohols,alkanes, esters, ketones and benzene. And it also has small amounts of aldehydes,pyran, alkenes and phenols. The relative content of alcohols is the highest, followed byester Aroma during developmental stages.The mainly Aromas are2-cyclohexyl-1- octanol,2-cyclohexyl-1-decanol,1,3,5-trimethoxybenzene and1,2-Benzenedicarboxy-lic acid, diisooctyl ester. Entire flower can be used for extraction of essential oils,irrigation before the harvest of cut flower can improve the quality of cut flowers.In summary, the cut flowers for storage should be gained during open-top stage(II level). Irrigation before the harvest of cut flower benefits the safe storage and thesafe storage temperature of cut flower is from-5°C to0°C.