Study On Mechanism And Control Technology Of Ji Zhua Disease Of Huangguan Pear

Huangguan pear is one of the major varieties of white pear lines, with early maturity, good quality, high yield, high resistance to scab and other excellent features in a new variety of pear, however the incidence of peel Ji Zhua disease become production and distribution bottlenecks during storage.In this paper, post-harvest Huangguan pear was the test material and was treated by calcium and coated with pullulan. The paper was focused on the different treatments on pear fruit during storage phenolic metabolism, lipid peroxidation, calcium content and ultrastructure, and explore between it with Ji Zhua disease occurred, revealing regulatory mechanism.(1) The phenolic metabolites results show that Huangguan pear peel phenols mainly contain chlorogenic acid, arbutin, catechin, caffeic acid, coumaric acid, and quercetin. Phenolic content of chlorogenic acid accounted for about 80% of the total substance was the role of the major PPO substrate. Dipped calcium and coated with pullulan pears delayed during storage speed phenol chlorogenic acid content decreased, inhibited PPO activity, reduced the incidence of chicken feet. The end of storage, control fruit incidence rate is 33.33%; fruit calcium treatment incidence rate is 0; fruit coated with pullulan incidence rate was 3.33%. Calcium treatment was the best.(2) The test results that atomic absorption teasted calcium changes of peel showed that Pear dipped calcium treatment increased the pear peel calcium content, increased water-soluble calcium peel, pectin calcium oxalate content; pears coated with pullulan did not change in total calcium content in pericarp, but changed the different forms of calcium content, and also improved the water-soluble calcium, pectin calcium oxalate content, but content less than calcium treatment.(3) Huanguan pear peal ultrastructure changed during storage .In the last stage of storage, disease site had a large area off the stratum corneum, the death of epidermal cells tissue after the last bolt of cloth, honeycomb, bare skin cells, tissue array clutter and clearly peg of thickened skin, and wax coverage also decreases; pears dipped calcium and coated with pullulan skin surface crack was very small and short, structured, and had no significant changes.(4) The lipid peroxidation results showed that pears dipped calcium and coated with pullulan during storage compared with the control, delayed the SOD, CAT activity decreasing speed and reduced the peak ofα-farnesene and conjugated trienes, delayed the peak time and inhibited MDA accumulation, had an effective system to prevent the destruction of the cell membrane and reduced the incidence of Ji Zhua disease. Calcium treatment mainly inhibited a large number ofα-farnesene synthesis, thereby reducing the content of conjugated trienes; coated with pullulan mainly inhibitedα-farnesene oxidation, thereby reducing the conjugated trienes accumulation. Two different treatments reduced the accumulation of conjugated triene by two different pathways.