Study On The In Vitro Micropropagation Of Tree Peony

Micropropagation in vitro does not find its use in propagation of tree peonies with the existence of some problems such as low multiplication rate, rooting and transplant difficulty of vitroplants, even though some advancement had been made in the latest twenty years in this field. To resolve these problems and establish a smooth protocol for the micropropagation of tree peony was the objective of this study. A lot of in-depth studies such as sterilization of explants, choosing of plant growth regulators and their concentrations and combinations, which had better effect on the multiplication of axillary buds, the effect of polyamines on the rooting of shoot cuts, releasing from dormancy to acclimatization and transplanting of rooted plantlets was conducted. Main results were as follows:1. Sterilization of explants:The optimal method for sterilization of explants differed in disinfector time and so on. The best method for sterilization of'Wu Long Peng Sheng'was 0.1% HgCl2 treated at 8 or lOmin,100% survival rate.2% NaClO and 1/10 of 84 disinfectant could also achieve sterilization, but occurrence of the higher hyperhydricity rate of explant, resulting in reduced effective survival rate.2. Choosing of plant growth regulators and their concentrations and combinations in culture medium:the culture medium had a change on the basis of WPM. The optimal concentration of BAP in the tests was 0.5 mg·L-1 and that of GA3 was 0.2 mg·L-1 with AgNO3 2.0mg·L-1. The four tested cultivars performed well on this medium. With the increasing of subculture times,'High Noon' had a stay effection on the multiplication, the average of multiplication was 5.43 per explant, but'wu long peng sheng','jin pao hong'and'ying ring hong'resulted in a decreasing of multiplication rate with increasing hyperhydricity rate, their average rate of proliferation was respectively 2.97,3.2,4.03.3. Rooting:rooting of 'High Noon'could be improved by exogenous PUT, SPM and SPD incorporation IBA 1.0mg·L-1 from 1～10mg·L-1. The optimal treatment of PUT for rooting of'High Noon' was 1.0 mg·L-1 combined with IBA 1.0 mg·L-1 and for 30 days, the rooting rate reached to 80.56%, and root number 4.35. The optimal treatment of SPM for rooting was 1.0mg·L-1 combined with IBA 1.0mg·L-1 and for 25 days, performing 46.36% rooting rate and 2.14 root number. The best treatment of SPD for rooting of'High Noon' was 1.0 mg·L-1 combined with IBA 1.0mg·L-1 and for 30 days, the rooting rate reached to 58.33% and 3.89cm of root length. In results, PUT performed better than the other two polyamines.4. Releasing from dormancy, acclimatization and transplant of rooted plantlets:To reclaim bud growing, it was helpful to chill the plantlet at 4℃for 30～60days. At the end of 4℃low temperature treatment, plantlets had an increasing growth in the leaf number, height and root length. Plantlets had an increasing growth and transplanting rate in a mixture with perlite:peat (1:1). Transplanting rate performed better in spring or winter. In this study, the better of the quality of plantlets, the higher survival rate in the transplanting.