Study On The Effects Of Chilling And GA₃ Treatments On Forcing Culture Of Tree Peony

Tree peonies (Paeonia suffruticosa Andr.) are traditional plants native to China, forcing culture has become an important part of the industrialization of tree peonies Releasing its dormancy needs a low temperature and period, GA3 also releases dormancy and advances flowering. So the period and temperature of chilling is important, either GA₃. In my study, such several traditional cultivars as 'Luo Yang Hong', 'HuHong', 'Wu Long Peng Sheng', 'Zhu Sha Lei', 'Rou Fu Rong', 'Yin Hong Qiao Dui', Hei Hai SaJin, 'Juan Ye Hong', 'Da Zong Zi' were cultured under the forcing condition and effects of different chilling period and GA₃ concentration on the growth rhythm, cumulative temperature, flowering time, flowering rate and flowering quality were studied. Main results were as follows:1. GA₃ efficiently released dormancy of tree peony and improved foliage expanding. When flower bud differentiation completed, if afford to the bud proper GA₃ treatment and temperature, it sprout and grow, but this maybe led to aborting subsequently.2. Chilling of 21-42 days at 4℃ efficiently released dormancy of all selected cultivars, and the cultivars flowered as expected. Chilling treatment advanced flowering, and flowering quality usually reduced, but the best chilling time for advancing flowering time and quality for different cultivars was different. In advancing flowering date, 28 days was best for 'Luo Yang Hong', but 35 days for 'Hu Hong', 42days for 'Wu Long Peng Sheng', 'Yin Hong Qiao Dui' and 'Da Zong Zi'; in improving flowering quality, 21 days was best for 'Hu Hong', 28 days for 'Luo Yang Hong', 'Yin Hong Qiao Dui', and 'Wu Long Peng Sheng', 42 days for 'Da Zong Zi'.3. Chilling and GA3 both affected the flowering quality of tree peonies. To a degree, GA₃ reduced flowering quality and the concentrations had a negative relation to the quality, but chilling period improved the flowering quality and had a positive relation, although it depended on cultivars. In an extent, chilling time and GA₃ relied on each other. Plants treated more chilling time endured higher GA₃ concentration. Commonly, best GA₃ concentration for flowering quality was lower than for flowering rate.4. Both chilling and GA3 reduced cumulative temperature and advanced flowering. But the most effective concentration and chilling period varied with cultivars. Higher GA3 concentrations were better for advancing flowering of 'Luo Yang Hong',n 'Hu Hong' , 'Wu Long Peng Sheng' and 'Rou Fu Rong', and it related to their chilling period; 'Yin Hong Qiao Dui' and 'Da Zong Zi' were sensitive to GA3, so lower concentration affected the cultivars greatly, and had little relation to chilling period.