Low Temperature Stress And Temperature Changes On The The Plums Physiological Characteristics And Mechanism Of The Impact Of The Organizational Structure

Study on Effection Mechanism of Low-temperature Coerce and Change-temperature Treatments on Physiology Characteristic and Tissue Structure of Plums Tutor: Prof Xinghua liu Vice-prof Huayun zhang Graduate :Xiulan Sun Abstract: The effection mechanism of low-temperature and change- temperature treatments on physiology characteristic and tissue structure of?Hei Hu Po 揳nd 揷huan Hong 損lums was studied in this thesis. The influence of four change- temperature patterns, such as, intermittent warming, 0----- 10~C dual temperature cycle, O-?.6扖 dual temperature cycle and decreasing temperature in sequence, on chilling injury was presented systemically with the -O.5-----OC constant low-temperature storage as matching test. The optimum change- temperature pattern was determined and the effect mechanism on chilling injury was discussed. All results would be theoretical basis and technology reference for commercial storage of plums. Study proved that -0.5 ??C constant low-temperature storage had low tempera- ture coerce on plums. ?Hei Hu Po 揳nd 揅huan Hong 損lums were observed obvious chilling injury symptoms on the fortieth day of storage. With the prolonging of storage time, chilling injury became more serious. Chilling injury promotes the increase of cell membrane permeability and MDA content. Cell membrane permeability was regarded as index of chilling injury and its degree of plums. And 45thday and 3Othday were the critical time of in reversed chilling injury of?Hei Hu P0 揳nd 揷huan Hong 損lums. Low temperature forced great increase of PPO-, POD activity, decrease of phenolic content, accelerated a flesh browning, broke up PG-. PE enzyme balance, made disorder in pectin metabolism, accelerated the decrease of reduced sugar and titrable acid content and shorten shelf life of plums. By Optical microscope, great changes happened in structure During the middle of storage, epidermis cell sank, cell wall was irregularly thickened, cell became long and gap between cells enlarged. At the end of storage, the cuticle broke, epidermis cells became overlapped, deformed and broke into pieces. A lot of things resembling cotton distributed in the gap. Intermittent warming lysised the low-temperature coerce efficiently, allevia- ted and delayed chilling injury symptoms, maintained normal physiological metabol- ism and obtained good quality and long shelf life. The results indicated intermittent wanning was the optimum pattern. Its operation was-O.5-----0C storage for lSd, warming to 18?0C then turning back -O.5---O~C, as a cycle. The mechanism of intermittent warming was that, by many times of short warming , cell membrane injury was repaired. This treatment retarded cell membrane permeabi- lity and MDA content, inhibited PPO-. POD activity and decreased of content, kept balance of PG and PE, returning into normal pectin metabolism, maintained high hardn- ess and delayed the decrease of reduced sugar and titrable acid content. The result of optical microscope indicated the well structure provided the basis of normale metabolism. 0?lOCand 0?.6扖dual temperature cycle had lysised the low-temperature injury, but for the sake of high temperature, promoted senescence, increased activi- ty of PPO~ POD and made LV the early occurrence of PG.~ PE activity peaks, accelerated pectin metabolism, so this treatment had a bad influence on s...