Study On Mechanism Of Chilling Stress To Nectarina In Greenhouse

Based on the greenhouse cultural practice of fruit trees in north china and using 4-year nectarine trees (Prunus persica var. nectariana cv. Shuguang) of greenhouse as materials in experiment, the research has been carried out at horticulture of Shandong University in 2000~2002 . The subject is mainly on influence of chilling stress on the growth and development of flower organs of nectarine, and the response and resistance of flower organs to chilling stress, which make certain the mechanism of injury of chilling stress and the response and resistance of nectarine to chilling stress. Then the ability of cryoprotectants were evaluated, and the most economical and effective one was selected. The main results were as follows:1. The difference of electrolyte leakage under the same low temperature and semi-point of flower organs showed that the hardiness of nectarine flowers organs was different among different growth and development stages of flowers organs. The 5-day young fruits after blossom with electrolyte leakage exceeding 58.90% and semi-point being -2.59℃ were the most sensitive to chilling stress than young fruits of other stages , buds and flowers.2. The semi-point of 5-day ,10-day and 15-day young fruits was -2.59℃, -6.86℃ and -7.64℃ respectively , which showed the hardiness of young fruit increased gradually with the growth and development of young fruits. Thus the electrolyte leakage of 5-day young fruits under the same low temperature were higher than that of young fruits of other two stages.3. Accumulation of poisonous material and osmotic stress due to cell dehydration were the main reasons of injury to flower organs. Under chilling stress poisonous material such as O2-, H2O2, MDA increased, especially under Zero, which showed injury deeply. Those material can make active component inactivate and membrane penetrability increased, which was the main and direct reason to mass leakage of electrolyte.4. The energetic response of flower organs to chilling stress was due to enhanced activity of protected enzyme and accumulation of osmotic material. Under chilling stress, the trend of protected enzyme activity protected enzyme increased then decreased, which embodied the inducementcharacteristics. But with the decreasing of temperature and the aggravating of osmotic stress, especially the accumulation of poisonous material and the integrity of cell membrane being destroyed, the activity of protected enzyme lost. Then the accumulation of osmotic and antioxidation material alleviate the injury and protect the activity of active material in cell or on cell membrane.5. There were differences in ability among cryoprotectants. The subject showed that the ability of 50mg.L-1 6-BA was best among 0.1%CaCl2 and 250mg.L-1 SA, and the ability of 0.1%CaCl2 than 250mg.L-1. Though the ability of 50mg.L-16-BA was most effective, its price was high. So 0.1%CaCl2 was considered as the effective and economical cryoprotectant which was adaptable to employ in vast areas to protect nectarine flower organs from freezing.