Research On Phylogenetic Relationship And Bud Differentiation And Re-blooming In Field Of Tree Peony Cultivars From Chinese Jiangnan Area

As one of the four famous peony cultivar groups, Jiangnan Group has a long history of cultivation. It had studied the genetic relationship of Jiangnan Group by the method of molecular marker, and then concluded the bud differentiation process and characteristics of each stage by microsection and exfoliative observation. Meanwhile some researches on the re-blooming technology of Jiangnan Group in the autumn had been conducted. The main conclusions were as follows:(1)The genetic relationships of 12 cultivars of Jiannan Group and 34 cultivars of 7 wild groups of Sect.Vaginatae were studied based on the SRAP and by cluster analysis it showed that there was the correlation between the tree peony cultivars and the color of flowers, so cultivars with the same or close flower color had the relatively close genetic relationship; the wild species of Subsect Vagiatae and cultivars of Jiannan Group were clustered together, which had a distant genetic relationship with the wile species of Subsect Delavayanae; Zhong yuan Group had a vital role in the cultivars'origin and evolution process of Jiannan Group, and the series cultivars of 'Feng Dan' might be directly evolved from P.ostii, and the cultivars from Japan and Europe-America were also useful in the origins of the cultivars of Jiannan Group.(2) By the microsection and exfoliative observation of two cultivars of Jian nan Group, besides flower bud differentiation undergoing the following stages in order: initial stage of flower bud differentiation, bract primordium differentiation phase, sepals primordium differentiation phase, petals primordium differentiation phase, stamens primordium differentiation phase, pistil primordium differentiation phase and stamen and pistil pistil petalody phase, it had observed that: the upper flowers'petals continued to differentiated from the lower flowers'pistil centers after lower flower differentiation was completed, then upper flowers'stamen and pistil were appeared to form upper flowers; the flowering of sepals were also involved in the process of flowertypes; bud differentiation process of early flower varieties(No.1)was faster than late flower varieties(No.2); the soluble sugar and soluble protein in the leaves reached maximum during the initial stage of flower bud differentiation, but they declined in the awake of a lot of energy in the plant was consumed during the bud differentiation and the variation of external environment, and finally they were in dynamic equilibrium.(3) With the help of GA3 to seven cultivars of Jiannan Group, 3 culvitars were selected which were suitable for blooming in autumn. GA3 can effectively break buds dormancying, promote the development of bud and leaves and improve the quality of flower. For example, the germination rate of cultivar No.6 reached to 60 percent after using GA3, the blooming rate reached to 42 percent, average flower diameter reached to 88.13mm, average flower branches'diameter reached to 2.74 mm, with a significant effect. The optimum GA3 concentrations of different cultivars were different, which should be taken into consideration. Meanwhile it showed that cultivars with simple or primitive flower pattern were easier to reblooming in autumn.