Peaches, cultivar ‘G.H. Hill’, from trees that were sprayed with 0, 25, 50 and 100 μmol L−1 sodium nitroprusside (SNP) 14 days before harvest were stored at 4 °C for 4 weeks. Chilling injury (CI), ethylene production, weight loss, firmness, malondialdehyde, hydrogen peroxide and vitamin C concentrations, antioxidant capacity (AC), and superoxide dismutase, peroxidase and polyphenol oxidase activities in the fruit were measured during storage. SNP treatments reduced ethylene production and maintained firmness, AC and vitamin C of the fruit. Treatment with 25 and 50 μmol L−1 SNP reduced CI but 100 μmol L−1 SNP increased it. SNP at 100 μmol L−1 promoted the accumulation of reactive oxygen species, decreased the activity of antioxidant enzymes and accelerated peroxidation in fruit during storage. These results indicated that preharvest SNP (25 and 50 μmol L−1) treatment increased chilling tolerance of peach fruit through suppressing ethylene production, maintaining firmness, AC and vitamin C and enhancing anti-oxidative enzyme activity.
