In vitro Culture Of Tree Peony Through Axillary Budding

Tree peonies are flowering shrubs which grow from 1 to 6 feet tall and are divided into two main groups: the hybrid and the non hybrid group. The latter ones are varieties of P. suffruticosa, comprising more than 500 cultivars. P. suffruticosa cultivars are used as outside ornamentals and as pot plants. Their cultivation under warmer climates, where the flowering process is accelerated, provides an excellent early market niche as cut flowers. The reproduction, under a commercial point of view, is mainly done by two primary methods of vegetative propagation: tuft division and grafting. In division methods, a large plant is simply divided into small plants, each bearing its own roots. In grafting methods, an herbaceous rootstock is used to nourish a tree peony scion until the tree peony produces its own sustaining roots. The choice of the propagation method is related to the degree of branching of plants which can present a different number of divisible bushes. Taking into consideration that these conventional propagation methods lead to a high cost of the plants due to technical and time-consuming difficulties (Aoki & Inoue, 1992), the peony culture could benefit greatly from micropropagation. A reliable micropropagation system might overcome these difficulties and it could also be used for the multiplication of virus-free stock material or new cultivars.