Research On Chilling Injury And The Cold Resistence Mechanism Of Apircot Fruit By Salicylic Acid Treatment

Xinjiang apricot fruit (Saimaiti) were taken as the test materials in this article, beginning with thecontrolled of postharvest chilling injury at low temperature storaged. The cold characteristics, the change ofquality, active oxygen metabolism, polyamines and the organizational structure of apricot fruit wereresearched by salicylic acid treatment.The improving mechanisms of postharvest cold resistance of apricotfruit by salicylic acid treatment were discussed, which provided some theoretical basis for the control ofpostharvest apricot fruit chilling injury.(1) Xinjiang apricot fruit (Saimaiti) were treated with0.01g/LSA by vacuum-infiltration and thenstored at0℃and90%~95%RH.The chilling injury incidence, chilling injury index, hardness, total solublesolids, titratable acidity, membrane permeability, juice rate, MDA content of apricot fruit were determined.The results showed that the chilling injury index, chilling injury incidence, membrane permeability, MDAcontent of apricot fruit by0.01g/LSA treatment were lower than those in the control, and the hardness, totalsoluble solids, titratable acidity, juice rate of apricot fruit by0.01g/LSA treatment were efficiently keep. Itis suggested that0.01g/LSA treatment could remarkably maintain the apricot fruit cold quality, which alsocould improve cold resistance of apricot fruit.(2) The O-.2production rate, hydrogen peroxide (H2O2) content and the activities of superoxidedismutase (SOD), catalase（CAT), peroxidase (POD) of the apricot fruit were determined. The resultsshowed that the O-.2production rate, hydrogen peroxide (H2O2) content in the treated apricot fruit werelower than those in the control, but the activities of SOD, CAT and POD were remarkably enhanced. It issuggested that the reduced incidence of chilling injury in SA-treated apricot fruit could be related to thebalance of reactive oxygen species metabolism, which was beneficial to decrease oxidative damage ofbiological macromolecule.(3) The contents of Put, Spm and Spd were determined. The results showed that the contents of Putwere obviously reduced by salicylic acid treatment, and the chilling injury delay7days happen, and significantly improve the Spm and Spd contents, make it keep the high level in the process of cold storage.These results demonstrate that the reduced index of chilling injury in SA-treated apricot fruit could berelated to the remarkably change of polyamines content in apricot fruit.(4) The changes of microscope and cell ultrastructure in early days of cold storage, metaphase of coldstorage and the end of cold storage of apricot fruits were observed by paraffin section and transmissionelectron microscope. The results showed that the cell ultrastructure of apricot fruit by salicylic acidtreatment and the controls have not significant differences based on cells arrangement in neat rows and theintegrity of the cell wall structure and the cell organells.The ultrastructure of apricot fruit changedobviously after28d,which exhibited that cell organelles was deformable or dissolved,gap junctionalintercellular enlarged,cell contents decreased,cell empty was cavity.Compared with the control,theimprovement of cold resistance in apricot fruit during the cold storage was closely related to the damagealleviation of the cell wall,chloroplast,mitochondria and the integrality maintenance of cell organelles andmembrane system by SA treatment.