| Tree peonies (Paeonia suffruticosa Andr.) are Chinese traditional excellentornamentals , and also world-wide famous flowers. Although having abundant species and cultivars of tree peony, China is rare of autumn-flowering cultivars reflowering in the same year. According to the history record and precedent researcher, China has autumn-flowering tree peonies resource. However, the unstable bud sprouting and the lower flowering quality make them devaluing. It will be have deeper influence on Chinese, if we could utilize these rare resources to force them reflowering in autumn, especially in Nation Day. In this article, autumn-flowering peony cultivars were collected firstly in Heze, Shandong Province; then reflowering culture by utilizing autumn-flowering peony cultivars in open field was studied systemically. Also photosynthesis characteristics of autumn-flowering cultivars during Spring and Autumn florescence were carried out. Finally, the physiological mechanism of reflowering of peony were discussed in order to guide focing culture in pactice. Major conclusions are listed as follows:1. Investigation and collection of autumn-flowering cultivars of tree peony and its autumn-flowering characteristics of were carried out. There are 45 autumn-flowering cultivars and about 4.5% of north china tree peony cultivars were collected. The time of autumn-spouting of peony floral buds focus from middle ten days of August to late September and the autumn-flowering time focus from early September to eary November respectively.2.The major field culture techniques to improve peony reflowering are listed:Autumn-flowering cultivars are better than non Autumn-flowering ones on leaf and flower qualityand forcing techniques. The age of plant from 8 to 15 has the best reflowering quality. Late August to early September is the optimum period to defoliation. Atificial defoliation by foliar spray of ABA and ethphon had a better effect on the quality of leaves and flower than by manual only. High concentrations of GA3 will be better to release floral bud from dormancy and improve reflowering quality, and also advance flower time. Sixteen peony cultivars were selected which behaved better in open forcing culture , and its flowering time can be controlled as long as 50 to 60 days. Four excellent cultivars can be controlled to flowering in Nation Day steadily.3. Study on photosynthesis characteristics of tree peony was carried out. The result indicated:(l)The diurnal curve of Spring and Autumn florescence photosynthesis showed two peaks. The net photosynthetic(Pn) rate of Spring florescence was higher than that of Autumn and has no significant differences among cultivars. The diurnal curve of transpiration rate and Gs also showed two peaks. There has different peaks of Pn in different seasons, April is higher than August, then October and last November.(2) Pn was significantly correlated with PFD, temperature, Gs, transpiration rate and so on. PFD and temperature have important influence on the Pn of different seasons. The light compensation point, light saturation point and Pn_max-L of LSP of spring photosynthesis were 22.56, 1401, 11.16 μmolm~2.s~-1 respectively and 15.84, 1206.5, 4.12 μmolm~2.s~-1 in autumn. The temperature compensation point, temperature saturation point and Pn_max.Tof TSP of Spring photosynthesis were 3.05℃, 30.75℃, 9.29 μmolm~2.s~-1 respectively and 4.31℃, 32.04℃, 3.26 μmolm~2.s~-1 in Autumn. All results above showed that the leaves of autumn-flowering was younger and has lower photosynthesis rate.4. Relationship between autumn-reflowering and metabolism of inner materials were listed as follows.(l)Endogeous hormone such as ABA, IAA, CTKs, GA3 have important influence on the autumn-flowering. Higher content of CTKs, GA3 ,IAA and lower ABA will improve reflowering of tree peony.(2)Content of protein and carbonhydrate was accumulated due to early defoliation which accelerated autumn-flowering of peony. Flowering will be failed if absence of protein and carbonhydrate.(3)Higher content of benzoic acid, sa...
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