| Tomatoes belong to chilling-sensitive plants. Chilling injury is easy to develop after cold storage. The quality of commodity of tomato fruits has been affected. Research on the mechanism of chilling injury of tomato fruit has important significance to realize the spring and winter storage, long-distance transportation and sales. Harvest maturity,1-MCP and ethylene treatments could influence the fruit to chilling stress response, and different fruits and vegetables on the response results are different. For the study of different maturity, 1-MCP and ethylene treatment on chilling injury of tomato response mechanism,’the fifth of Huang Guan’ tomatoes are the experimental material in this paper. The effect of harvest maturity(green mature period, white mature period, color changing period and pink mature period)and 1-MCP(1 μL/L), ethylene(0.05% and 0.1%)treatment on chilling injury and quality of tomatoes was studied. The objective of this research was to find the harvest maturity of the most suitable for cold storage and the optimum concentration of ethylene. And we have analyzed the differences of cold tolerance of tomatoes among the different treatments in reactive oxygen metabolism and cell wall metabolism, which provides a theoretical basis and practical experience for the preservation tomato fruit. The results indicated that:1. The study of effect of harvest maturity on chilling injury and storage quality of tomato fruits showed that low mature fruits were more susceptible to chilling injury. Chilling injury index of green mature period fruits was 1.57 times of white mature period,11.88 times of color changing period and 20.09 times of pink mature period after shelf life for 6 days. Storage quality of the high mature tomato was better. Which TSS, Vc, total phenol and lycopene content was higher than low maturity. In pink stage, the permeability of cell membrane was lower than that of the green ripe stage 21.32%, and the content of MDA was lower than that of the green ripe stage 0.78 nmol/g.2. The study of effect of harvest maturity on active oxygen metabolism of tomatoes showed that the content of O2- and H2O2 of low mature fruits increased slowly. Compared with high mature fruits, SOD, APX and GR ahead of time 9 d peak appeared in low mature fruits. Tomato fruits with advanced maturity contained higher GR and POD activities. Chilling injury of tomato fruits was closely related to changes of cell membrane permeability. The study of active oxygen metabolism related index and cell membrane permeability by path analysis showed that O2- was the greatest direct effect for effect to cell membrane permeability of low mature fruits, and POD was the greatest direct effect for effect to cell membrane permeability of high mature fruits.This showed that the high POD activity and low O2- were the important reasons for the strong cold tolerance of high mature tomato fruits.3. The study of effect of harvest maturity on cell wall metabolism of tomato fruits showed the main difference of cell wall metabolism of low and high mature fruits was the pectin degradation and cell wall degrading enzymes activitivies. Low temperature stress inhibited PG and Cx activitivies increasing of low mature fruits, causing pectin degradation blocked. The study of cell wall metabolism related index and firmness by path analysis showed that CWM was the greatest direct effect for effect to firmness of low mature fruits, and PG was the greatest direct effect for effect to firmness of high mature fruits.This showed that PG activity and low CWM content of high mature tomato fruits were important reasons for its normal softening.4. The study of effect of 1-MCP and ethylene treatment on chilling injury and storage quality of tomato fruits showed that CI was the lowest, only 8% 1-MCP at the end of storage, and quality of fruits was best by 0.1% ethlyene treatment. Quality of fruits was worst by 1-MCP treatment. Ethlyene treatment prmoted fruits soften and redden, inhibited TSS, total phenolic and Vc content declining, promoted the synthesis of lycopene, delayed the cell membrane permeability increasing, inhibited the accumulation of MDA content.5. The study of effect of 1-MCP and ethylene treatment on active oxygen metabolism of tomatoes showed that ethylene treatment could inhibit the accumulation of O2- and H2O2 content, improve active oxygen scavenging enzymes activities. The study of active oxygen metabolism related index and cell membrane permeability by path analysis showed that O2-was the greatest direct effect for effect to cell membrane permeability of 1-MCP and CK. O2-, SOD and CAT were greater direct effect for effect to cell membrane permeability of ethylene treatment. This indicated that increased SOD and CAT activity increased of ethylene treatment were important reasons to reduce the chilling injury.6. The study of effect of 1-MCP and ethylene treatment on active oxygen metabolism of tomatoes showed that ethylene treatment could increace the activities of PG, PME and Cx, promote the degradation of cell wall substances and the solubilization of pectin. The study of cell wall metabolism related index and firmness by path analysis showed that CWM was the greatest direct for effect to firmness of 1-MCP and ethylene treatment fruits. PG was the greatest direct for effect to firmness of 1-MCP and ethylene treatment fruits.This showed that ethylene treatment to improve the PG activity of tomato fruits was an important reason for the normal softening. |
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