【作者】 邵好好；

【导师】 马锋旺；

【作者基本信息】 西北农林科技大学 ， 果树学， 2003， 硕士

【摘要】 休眠是北方落叶果树长期形成的一种对季节性气候变化生物适应和驯化的结果。果树进入休眠后，体内的生理生化活动并未停止，甚至有些代谢过程被激活。本试验以梨树品种砀山酥、八月红、5-16、粗皮梨和早酥为试材，系统研究了温度日循环和持续低温对梨树需冷量积累和梨树花芽萌发的影响，以及在温度日循环处理期间、硫脲处理后和自然休眠期活性氧和抗氧化系统的动态变化。结果如下： 1、温度日循环处理和持续低温对梨树花芽萌发率的影响存在差异。持续低温处理20d（需冷积累480CUs），早酥梨花芽萌发率超过50％，5-16、砀山酥、粗皮梨和八月红的萌发率均低于50％。表明梨树的不同品种的需冷量存在差异。温度日循环（20℃4h/4℃20h）处理20d后，八月红花芽萌发率没有超过50％外，其它供试品种萌发率均超过50％。粗皮梨、5-16和砀山酥温度日循环处理后萌发率显著大于持续低温处理花芽的萌发率，早酥两种温度处理后花芽萌发率没有显著差异性（P=0.05），说明梨树多数品种温度日循环处理解除休眠的效果优于持续低温。 2、自然休眠过程中，花芽的活性氧和抗氧化系统发生变化。O₂^?产生速率在休眠前期上升，在休眠后期下降。H₂O₂在休眠开始后含量很快上升，休眠后期和花芽萌发期含量快速下降。抗氧化系统中SOD活性在自然休眠期活性呈下降趋势，自然休眠结束活性上升。POD活性一直上升。CAT酶的活性受到H₂O₂含量的影响，活性上升，并在整个休眠期保持较高活性水平。抗氧化物质AsA和GSH含量随休眠进行而下降，休眠解除过程升高。抗坏血酸—谷胱甘肽循环的两个关键酶APX和GR的活性在自然休眠期变化相似，休眠期间活性下降，休眠结束活性迅速上升。 3、温度日循环、硫脲处理使花芽活性氧和抗氧化系统发生变化。O₂^?产生速率上升，H₂O₂含量呈上升趋势。抗氧化系统中SOD活性随处理时间延长下降，POD活性上升，CAT的活性也上升。温度日循环处理期抗氧化物质AsA和GSH含量下降，而硫脲处理后含量上升。两种处理过程中APX和GR活性均上升。更多还原

【Abstract】 North deciduous fruit trees evolved into biomechanism of dormancy for a long time to adapte to environmental and climatical changes in winter. The physiological and biochemical metabolisms did not stop, but even were inactivited. Some pear cultivars including ’dangshansu’, ’bayuehong’, ’5-16’, ’cupili’ and ’zaosu’ were selected as material in this experiment to study systemically effects of temperature daily cycle and maintained low temperature treatment on the accumulation of chilling requirment and the opening of flower buds., and elucidating the changes of active oxygen and antioxidative system during temperature daily cycle and winter dormancy and after applying thioureas. The results were as follows:1. Differences were found in budbreak between two exposures of maintained low temperature (4 ) and temperature daily cycle (20 4h/4 20h). All materials were exposed to the continuous low temperature for 20 days, the budbreak rate of flower bud only in ’zaosu’ pear reached beyong 50%. This meant that there were differences in chilling requrement among cutivars in same pear species. After 20 days exposure of temperature daily cycle, the budbreak rates of these cutivars were all beyong 50% except ’beyuehong’. The budbreak rates of exposure to temperature daily cycle treatment were higher than those of ’cupili’, ’5-16’ and ’dangshansu’ exposed to maintained low temperature except ’zaosu’ ( at significantly different level 0.05). Results indicated that accumulation of chilling of exposure to temperature daily cycle more effective than that of exposure to maintained low temperature.2. Active oxygen and the antioxidative system changed much during natural dormancy. The production rate of O2 increased at early stage and then decreased. Increases in H2O2 appeared as soon as dormancy began, decreases at the end of dormancy and during the period of budbreak. The SOD activity in antioxidative system dropped , thePOD activity increased continuously, the CAT activity showed the same result caused probably by the content of H2O2 during winter dormancy. Two important antioxidants AsAand GSH decreased with the process of dormancy, and then increased at the last time of dormancy. Two of key enzymes in ascorbate-glutation cycle changed similarily, increased in process of dormancy, then decreased finally.3. Active oxygen and the antioxidative system also changed much in both temperature daily cycle and thioureas treatment. The production rate of O 2 rised up, the content of H2O2 too increased . The activity of SOD decreased with the extended time of exposure, however, both the POD activity and the CAT activity went up. The contents of antioxidant AsA and GSH decreased after exposure of temperature daily cycle, increases after exposure of thioureas. Both two treatments all increased the activity of APX and GR.更多还原