Reduced chilling injury in cucumber by nitric oxide and the antioxidant response

Cucumber fruit were pre-treated with 25 μl l−1 nitric oxide (NO) for 12 h at 20 °C, and then stored at 2 ± 1 °C and 95% relative humidity for 15 days. Chilling injury index, membrane permeability, lipid peroxidation, superoxide anion ( O 2 - ) production rate, H2O2 content, activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), and DPPH-radical scavenging activity were measured. The results showed that the application of NO at 25 μl l−1 was most effective in reducing CI in cucumber fruit. The treatment reduced the increases in membrane permeability and lipid peroxidation, delayed the increases in both O 2 - production rate and H2O2 content. The NO-treated fruit exhibited significantly higher activities of SOD, CAT, APX and POD and higher DPPH-radical scavenging activity than control fruit during the storage. The overall results suggest that NO enhanced chilling tolerance in cucumber fruit by improving the antioxidative defence system.