Investigation Of Tree Peony Resources In Hunan And Germination Of Paeonia Suffruticosa ’Xiangdan’ Seeds

Hunan tree peony is an important branch of Jiangnan tree peony groups, with a long cultivation history. In recent years, the lack of systematic investigation, conservation and collection has caused families ill-defined and confusion in species for Hunan tree peony resources. In addition, poor cultivation techniques also limits the development and utilization of Hunan tree peony resources. In this paper, the planting distribution, variety situation and growth status of Hunan tree peony are comprehensively collected through field investigation into Changsha City, western Hunan, Shaodong County and Ningxiang County. Moreover, the seed germination of medicinal peony cultivar P.suffruticosa ’Xiangdan’ has also been studied, all the results are as follows:1、Characteristics of Hunan tree peony resource(1) Distribution characteristics:The distribution of wild peony in Hunan is extremely rare. Cultivation of peony in Hunan is mainly divided into traditional cultivars and introduced cultivars, Shaodong county is one of the largest cultivation base for traditional native medicinal varieties, Yongshun county is the main cultivation base of ornamental peony, introduced cultivars are mainly distributed in Ningxiang county and Changsha.(2)Variety features:According to the survey,24 local varieties had been preliminary summarized,16 of which had been recorded in the<Chinese Peony>(Volume Jiangnan),8 variant parentages were newly discovered; a total of 136 varieties were introduced, coming from 7 main peony producers respectively:the Central Plain, Jiangnan, Southwest China, western Hubei, Japan, Europe and the United States. The diversity of the phenotypic traits of local varieties such as the color, flower pattern and plant type are significantly lower than the introduced ones; while the native peonies show better resistance to high temperature and high humidity climate. Among the introduced varieties, of which Jiangnan, Southwest China and Western Hubei show the best adaptability, followed by the Japan, Europe and the United States group, with the central plain group coming in the last.(3)The new variant strains: ’Cili red’, ’Dancing butterflies’,’Smokey Purple’ ’Fengjinhe’,’Star games’,’Fengzihe’,’Jiaoyuan’, and ’Fenzilou’. Compared with the existing records, these new mutations mainly have the difference in the flower color, pattern, and color markings.2、Seed germination of P. Suffruticosa ’Xiangdan’(1) Temperature and GA3 treatment can effectively break seed hypocotyl dormancy of P. Suffruticosa’Xiangdan’, promoting the rooting rate, advancing the first rooting time and shorten rooting duration, helping to complete rooting process ahead of schedule. With the GA3 concentration rising, the rooting rate and the rooting index showed a similar trend of falling after rising. In addition, they both reached the maximal value when the 350mg/LGA3 with 15℃ constant temperature treatment was applied; the starting and ending time of rooting advanced as the GA3 concentration going up, besides,15℃ constant temperature treatment is more beneficial to advance the rooting process. In general, after soaked in 350 mg/LGA3 for 12 hours, stored at temperature constant at 15℃ is the optimum condition to promote rooting(2)The basic condition for breaking epicotyl dormancy of P. Suffruticosa’Xiangdan’ seeds:Main root grows over 5cm. Microscopic morphology shows that when the main root is longer than 50mm, the epicotyl is completely developed, and can satisfy seed germination.(3)Chilling and GA3 treatment can effectively break seed epicotyl dormancy of P. Suffruticosa’Xiangdan’, promoting the germination rate, advancing the starting time of germination, accelerate the germination speed. With the increase of GA3 concentration, the starting time and the duration of germination would be shorten. In addition,under the treatment of 27 days chilling and 400mg/LGA3,the starting and ending of germination came earliest. With the rising of chilling days, the germination rate and the germination index would be improved, and they were also positively correlated with the GA3 concentration, the maximal value achieved when the 400mg/LGA3 treatment was applied. In general, after 27-day low temperature(4℃) treatment, then soaked in 400 mg/LGA3 for 6 hours and stored in greenhouse (15℃-25℃) is the optimum condition for seed germination.