Crosses of Paeonia ostii Feng Dan Bai'as maternal parents and an analysis on the potential in tree peony breeding

Self-compatibility, fertility and breeding potential of Paeonia ostii Feng Dan Bai'( Phoenix White'), a famous medicinal and oil cultivar of tree peony, were studied in this paper. We crossed P. ostii Feng Dan Bai'with 57 cultivars from P. suffruticosa Zhongyuan Group, P. suffruticosa Japan Group and P. rockii Rock Group in 2008, 2009 and 2011, during which totally 2 023 flowers were pollinated in 57 different cross combinations with the harvest of 43 508 seeds. The main results were as follows: 1)the seed setting rate of open-pollinated flowers (19.13 seeds per flower) was significantly higher than that of self-pollinated flowers (0.4 seeds per flower), indicating that Feng Dan Bai' is cross-pollinated plant without apomixis. 2) In crosses with the cultivars of P. suffruticosa Zhongyuan Group, P. suffruticosa Japan Group and P. rockii Rock Group, Feng Dan Bai'had high average setting rates (respectively 18.44, 23.84 and 26.62 seeds per flower),which indicated it had obvious cross- compatibility with various cultivars. 3) Setting rate was affected by flower forms of pollen parents used in crossings, among which the crown form (10. 42 seeds per flower) was the lowest and significantly different from other forms. This should be caused by the decrease of pollen numbers and vitality with high petaloidy of flowers. 4)In the crosses with 39 cultivars such as Gui Fei Cha Cui'and Hei Long Jin', Feng Dan Bai' had higher average setting rates (respectively 33.33, 35.89 seeds per flower, et al) than open-pollinated flowers, which represented an important clue for improving seed yield of oil tree peony. In conclusion, Feng Dan Bai', with strong fertility and compatibility, has great potential in tree peony breeding and can be used as an excellent maternal parent in the future.