Research On Bud Differentiation And Re-blooming Characteristic Of Tree Peony

Tree peony is originated in China, but its modern cross-breeding developed rapidly in Europe and North America after being spread into these areas. Paeonia delavayi var. lutea and Paeonia delavayi were used in distant hybridization by breeders there and numerous excellent cultivars have emerged.'High Noon' , a lutea hybrid was selected and its flower bud differentiation process and re-blooming characteristics was researched; Meanwhile, a common cultivar' Jinpaohong' was taken as the comparison. The floral development was studied by serial microtomy and scanning electron microscope(SEM ). Knowledge about lutea hybrids' growth, blooming habit and flower bud differentiation were gained based on this research, also, the general rules and characteristics on annual growth cycle and flower bud differentiation of lutea hybrids and common type cultivars is summarized, which has enriched the basic rules of peony flower bud differentiation. The main conclusions are as follows:(1) 'High Noon' can bloom several times a year, whose first flowering season starts at the beginning of May, between the herbaceous peony and the Chinese tree peony, and lasts for a month; while the second flowering season at the beginning of August, even a few flowers blossoming from September to October.(2) Most of re-blooming peony terminal bud and high position lateral bud are precocious, can sprout massively in growth season. The terminal bud completes life cycle in one year and the lateral bud life cycle lasts two years: The hibernaculum has two development paths, first, lateral bud life cycle is three years and terminal is two which are same as common type peony (P. × suffruticosd). Second, the bud on stopped growing secondary shoot can develop rapidly and bloom next year, whose life cycle is two years.(3) Differentiations in re-blooming peony can be generated several times within a year. The precocious flower bud formatting from July to the early August is bare bud and last about 20 days in individual differentiation; it will grow and bloom immediately after completing the differentiation process. Mixed bud differentiates from September, but with a disorder development process among individuals, some may retard to the next year, thus extending the spring flowering season.(4) The peony hibernaculum which are all mixed buds have two developing paths: generally speaking, the mixed bud starts in lateral bud primordium or leaf bud terminal meristem, and then initiated scale leaf, leaf primordium, bract primordium , sepal primordium and other flower organs. After dormancy break, mixed bud will bloom next year. Second, lutea hybrids 'precocious bud can (?) and format secondary shoot. The bud on secondary shoot could complete all the differentiation process and format mixed bud by dormancy stage. The re-blooming peony precocious flower bud without dormancy is bare, which can format on secondary shoot terminal meristem rapidly. It will grow and bloom immediately after completing the differentiation process...