| Ziziphus muaritiana has high economic and nutritional value.But ziziphus muaritiana after harvest is not easy to keep fresh,easy to get rotten,quality becomes worse,has short shelf life and great losses in economy.'Zhongqing' ziziphus muaritiana fruits,were treated with AnsiP-STM for 12 hour,at room temperature and stored in the condition of?15±1??,75%relative humidity in this study.The rusults were as follows:1.In this experimentation,the 'Zhongqing' ziziphus muaritiana fruits were treated with 0,1.5,1.8,2.1 ?L·L-1 1-methylcyclopropene?1-MCP?.The results showed the treatment of 1-MCP lowered the respiration rate of 'Zhongqing' ziziphus muaritiana fruits,it could delay the increase of cell membrane relative leakage rate of fruit,maintaining higher fruit firmness,higher contents of titratable acid in fruit and Vitamin C,together with decreaseing fruit decay and fruit weight loss,delay the arrival of the peak fruit soluble solids content,keep the fruit with good quality. Among the above fruits treated with different concentration of 1-MCP,the effects are distinctly different,in which the fruits pre-treated with 1.8 ?L·L-1 1-MCP showed the best fruit quality.So it was chosed as the optimum conditions of 1-MCP treatment for the harvested ziziphus muaritiana fruits in this study.2.The treatment of 1.8 ?L·L-1 1-MCP maintained higher activities of active oxygen scavenging enzymes,such as superoxide dismutase?SOD?,catalase?CAT?and ascorbate peroxidase?APX?and contents of endogenous antioxidant substances such as glutathione?GSH?and ascorbic acid?AsA?,and obviously decreased the O2-' production rate and malondialdehyde?MDA?content in sarcocarp of 'Zhongqing' ziziphus muaritiana fruit.From the results,it could be concluded that 1-MCP treatment enhanced active oxygen scavenging capacity,which reduced the accumulation of reactive oxygen species that can undermine cell membrane structure,and delayed membrane lipid peroxidation of 'Zhongqing' ziziphus fruits,which retarded their senescence.3.The treatment of 1.8 ?L·L-1 1-MCP inhibited 'Zhongqing' ziziphus muaritiana the the activity of LOX,lipase and PLD,reduced the MDA accumulation,maintaining higher relative contents of unsaturated fatty acids,such as oleic acid,a-Linolenic acid,etc.and lower relative contents of saturated fatty acids,such as Palmitic acid,Margaric acid,Stearic acid,Arachidic acid,as a result,the index of unsaturated fatty acids?IUFA?and unsaturated degree of fatty acids were increased.From the results,it could be concluded that the higher disease resistance of postharvest 1-MCP treatment 'Zhongqing' ziziphus muaritiana is due to decreases of activities of cell membrane lipid related degradation enzyme,which may reduce the degradation of unsaturated fatty acids of membrane lipids and maintain higher unsaturated degree of fatty acids,increasing the liquidity in the membrane,in turn,resulted in maintaining integrity of cell membrane structure and compartmentalization within the cell,elaborated the senescence of'Zhongqing' ziziphus muaritiana.4.The treatment of 1.8 ?L·L-1 1-MCP maintained 'Zhongqing' ziziphus muaritiana higher contents of adenosine triphosphate?ATP?,lower the contents of adenosine diphosphate?ADP?,adenosine monophosphate?AMP?,as a result,it maintained a higher level of energy charge.1-MCP treatment kept higher activities of H+-ATPase,Ca2+-ATPase and Mg2+-ATPase of protoplasm,vacuole and mitochondria,also kept higher activities of cytochrome c oxidase?CCO?,prevent loss of cell membrane selectivity,maintain the integrity of the cell membrane structure.The treatment of 1.8 ?L·L-1 1-MCP maintained higher contents of NADK,so as to make higher contents of NADP,NADPH and lower contents of NAD,NADH,improve the efficiency of the fruit cell oxidative phosphorylation,elaborated the senescence of 'Zhongqing'ziziphus muaritiana5.The treatment of 1.8 ?L·L-1 1-MCP maintained 'Zhongqing' ziziphus muaritiana higher activities of PAL,so as to make higher contents of lignin and total phenolic,and thus reduce the decay and disease index,improve activities of GLU,CHI.from the results,it could be concluded that the higher disease resistance of postharvest 1-MCP treatment 'Zhongqing' ziziphus muaritiana is because higher contents of disease resistance related material and activities of disease resistance related enzymes.The treatment of 1.8 ?L·L-1 1-MCP maintained 'Zhongqing'ziziphus muaritiana higher disease resistance,elaborated the senescence. |
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