Effect And Mechanism Of Short-term Heating Treatment On Breaking Bud Dormancy In Peach Trees

Deciduous fruit trees protected cultivation is a new and efficiency culture form in northern China. The experiment was carried out with 4-year old trees (Prunus persica var. compressa cv.Zaolu.) for analyzing some physiological changes in dormant floral buds and shoot cortex under short-term heating treatments, investigating and calculating the chilling requirements of peach floral buds. The main results are as follows:1. The 'Zaolu' peach had different chilling requirements significantly between the flower buds and the leaf buds. The chilling requirement of flower buds was higher than that of the leaf buds. In 2005, the chilling requirements of flower and leaf buds were 570h and 670h, separately. The results demonstrated that =7.2℃ model was more applicable to evaluate the chilling requirement than 0~7.2℃ or the Utah model under experimental conditions.2. After 'Zaolu' peach fell the dormancy, as long as it gained enough chilling requirements, its dormancy should be relieved by the short-term heat treatment The results indicated that postponing the date of treatment, increasing heat temperature or extending period of heating enhanced the effect of relieving the dormancy of flower and leaf buds.3. The activity of SOD had a flood tide in the former period of dormancy, then kept a decrease continually, after dormancy being broken the SOD activity increased rapidly. During natural dormancy period, POD activity kept an increase continually, and also had a high level when dormancy is being broken.4. In the process of relieving the natural dormancy, the O2: content of the flower bud and cortex increased, which increased the penetrability of cell membrane meanwhile, the MDA content and the relative conductivity increased, also.5. In the entire dormancy process, the changes of soluble protein content in the flower bud and the cortex showed "S" curve, About a week before relieving the natural dormancy, soluble protein content fell down to the minimum value, then began to increase. The change of soluble protein content was associated with the dormancy relieving.6. The short-term heat treatment promoted relieving the dormancy of 'Zaolu' peach flower bud in some extent. When treating with high temperature to relieve the dormancy,the SOD, POD activity of short-term heat treatments was higher as compared with control.7. all the high-temperature treatment increased the (V content of the flower bud and the shoot cortex in some extent, thus causes the cell membrane penetrability to be increased, the MDA content increased, the relative conductivity increased, various high-temperature treatment O2 content and the MDA content as well as the relative conductivity of flower bud and shoot cortex are higher than the comparison remarkably.