Effect Of 24-Epibrassinolide On The Cold Resistance Of The Postharvest Apricot Fruits

Xinjiang apricot fruit(Saimaiti)were taken as the test materials in this article,To explore effect of24-Epibrassinolide on the cold resistance of the postharvest apricot fruits,through the determination of storage quality,active oxygen metabolism and related indicators of cellular ultrastructure,the mechanism of EBR treatment on post-harvest cold resistance improvement of apricot fruit was studied.,it provides a theoretical reference for EBR in apricot fruit storage and control and chilling injury.(1)0.9 mg/L of 24-brassinolide(EBR)was used to decompress the apricot fruits under a pressure of 0.05MPa for 2 min.Distilled water was used as a control,and the treated fruit was allowed to continue soaking for 5 min under normal pressure.Take out the air and store it in a cold room with a temperature of 0?and an RH:90%-95%.The index of cold injury,the incidence of cold injury,hardness,soluble solids content,chlorophyll content,titratable acid content,ascorbic acid content,malondialdehyde content,respiratory intensity,and weightlessness rate of apricot fruit were measured regularly every 42 days for a total of 42days.The experimental results show that EBR treatment can reduce the decrease of soluble solids,titratable acid,chlorophyll and ascorbic acid during apricot fruit storage.Effectively reduce the cold injury index of apricot fruits and the incidence of cold injury,delayed the increase of malondialdehyde content,respiratory rate and weight loss rate.(2)Regular determination of the activity of catalase(CAT),ascorbate peroxidase(APX),glutathione reductase(GR),superoxide dismutase(SOD)and peroxidase(POD)in apricot fruits The production rate of superoxide anion radical(O₂^-)and the content of hydrogen peroxide(H₂O₂)and reduced glutathione(GSH).The results showed that EBR at a concentration of 0.9 mg/L could effectively increase the activities of SOD,APX,and GR in apricot fruit,slow down the decrease of POD and CAT activity during apricot fruit storage,and inhibit the increase of H₂O₂,GSH content and O₂^-production rate.This indicated that EBR treatment could reduce the cold damage of apricot fruits and prevent oxidation damage during the cold storage of fruits,and the clearance of free radicals was closely related to the accumulation of free radicals.(3)Transmission electron microscopy was used to observe the changes of ultrastructure of apricot fruit during cold storage,mid-refrigeration and cold storage.At the early stage of cold storage,the cell wall and organelles of apricot fruit in the EBR-treated and control groups were well arranged,and the organelles were clearly visible without any significant difference.From the 28th day of cold storage,the ultrastructure of apricot fruit cells changed significantly.In the control group,apricot fruits showed cell wall and organelle deformation,cell space enlargement,plasmolysis,and cell cavitation.Compared with the control group,EBR treatment can better alleviate the damage of cell structure of apricot fruit under low temperature,maintain the integrity of cell system and membrane system,and thus improve the cold resistance of apricot fruit during cold storage.