Abstract: To investigate the effect of postharvest NO treatment on the metabolism of reactive oxygen species (ROS) and physiological quality of litchi fruit, harvested fruit were soaked in different concentrations (10, 50 and 100 μmol/L) of sodium nitroprusside or water as a control. The changes in physiological indexes were measured regularly during storage at 4 ℃. The results showed that sodium nitroprusside treatment could significantly reduce the mass loss rate, inhibit the generation and accumulation of hydrogen peroxide (H2O2) and superoxide anion (O2-·), reduce the production of malondialdehyde (MDA) as a cell membrane lipid peroxide product and membrane permeability, improve the activity of antioxidant enzymes such as superoxide dismutase (SOD), and slow down the senescence and browning of litchi fruit. Treatment with sodium nitroprusside at 10 μmol/L could significantly delay the increase in browning index and decrease the permeability of the cell membrane, and at 100 μmol/L effectively reduce the mass loss rate and increase the activity of SOD at the middle and late stages of storage. The results from principal component analysis showed that the key factors affecting the quality of postharvest litchi fruit were browning index, membrane permeability, mass loss rate and SOD activity, and the comprehensive score of litchi fruit treated with 100 μmol/L sodium nitroprusside were higher at the late stage of storage (after six days), and its storage quality was the best. These results indicated that sodium nitroprusside treatment could effectively delay the senescence and browning of litchi and prolong its shelf life by regulating ROS metabolism.

Key words: litchi; sodium nitroprusside; physiological quality; principal component analysis