Exogenous Melatonin Ameliorates Postharvest Chilling Injury of Apricot Fruit by Modulating Reactive Oxygen Species Metabolism

In this study, the effects of melatonin on chilling injury and reactive oxygen metabolism were investigated during the storage of postharvest apricot fruit at (0 ± 1) ℃ and 90%–95% relative humidity. ‘Saimaiti’ apricots were impregnated with different concentrations of melatonin (50, 100 and 200 μmol/L) at 0.05 MPa for 2 min and then at atmospheric pressure for 8 min before storage. Distilled water was used as a control. Chilling injury incidence and chilling injury index were periodically recorded, and malondialdehyde (MDA) content, cell membrane permeability, superoxide anion radical production rate, H₂O₂ content and antioxidant enzyme activities were measured in apricot fruit. Compared to the control group, melatonin treatment obviously reduced chilling injury incidence and index in apricot fruit (P < 0.05), and 100 μmol/L melatonin was the most effective in reducing chilling injury. Furthermore, apricot fruit treated with melatonin increased the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), inhibited the accumulation of superoxide anion radical and H₂O₂, reduced membrane lipid peroxidation, and maintained membrane integrity. These results suggested that the inhibition of exogenous melatonin on chilling injury of apricot fruit was closely related to the regulation of reactive oxygen metabolism. These findings can provide a theoretical basis for the application of melatonin in controlling chilling injury of postharvest apricot fruit.