Changes Of Fruit Structure And Physiological Metabolism And Roles Of Chemical Regulator Under Low Temperature Stress

Fruit are usually stored in low temperature conditions in order to slow physiological metabolism, keep quality and extend storage life. However, many fruit are sensitive to chilling below 10 oC~12 oC. Chilling injury often occurs in fruit when they are under chilling temperature causing the loss of quality and business value. Thus studying how chilling injury induced and cold resistance enhanced for postharvest horticultural products is a scientific issue of economic value. Methyl salicylate and methyl jasmonate are signaling materials made by numerous plants and were revealed capable of reducing chilling injury and increasing cold resistance in fruit though relevant mechanism was unclear. This dissertation used mango, peach and cucumber as materials to study the changes in antioxidant metabolism, phenolic metabolism, cellular membrane integrity, and components and structure of cell wall, and finally confirmed that methyl salicylate and methyl jasmonate could alleviate chilling injury in fruit and meanwhile discussed the mechanism for enhanced chill resistance.Surface waxes of the pericarp were observed by scanning electron microscopy (SEM); the structure and composition of cell wall were studied using light microscopy, transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) microspectroscopy respectively; the changes of calcium in the cell wall were determined by atomic absorption and the integrity of cell membrane by conductivity meter respectively. Meanwhile, in order to understand the roles of antioxidant stress reaction and phenolic metabolism in the chilling tolerance of fruit, the activities of...