Synergistic Effects of Nitric Oxide Combined with Clove Essential Oil Atomized Fumigation Treatment on the Postharvest Storage Quality of Peach

The present study aimed to investigate the synergistic effects of nitric oxide combined with clove essential oil on the postharvest storage quality of peach fruit. The harvested peaches were treated with the sodium nitroprusside and clove essential oil using atomized fumigation. The firmness, ethylene release rate, decay index, titratable acid content, soluble solid content, cell wall polysaccharide contents, cell wall degradation enzymes activity, defense-related enzymes activity, tissue structure and cell wall ultrastructure were analyzed in peaches during the storage period at 0 ℃. The results indicated that the combined atomized fumigation treatment had a better preservation effect on peaches, in comparison with the nitric oxide or clove essential oil alone. The decay index of peach fruit treated with the combined treatment was only 9.25% during the 35 d of storage. The ethylene release rate of combined treatment was reduced by 34.88% while the firmness, titratable acid, and soluble solid contents of peaches fruit was increased by 22.01%, 31.68% and 5.90%, respectively, when compared to the untreated fruit on day 35. Furthermore, the combined treatment inhibited the activities of polygalacturonase, pectin methylesterase, cellulase and β-galactosidase activities. The water-soluble pectin content of combined treatment was reduced by 21.88% compared to the control group. The contents of chelate soluble pectin, sodium carbonate-soluble pectin, hemicellulose and cellulose components increased by 23.40%, 21.31%, 36.62% and 39.89% respectively, thereby maintaining the integrity of the cell wall structure and delaying the fruit softening. We found that combined treatment enhanced the defense enzyme activities of phenylalanine ammonia-lyase, and 4-coumarate coenzyme A ligase activities. Cinnamate-4-hydroxylase activity of combined treatment was 15.71% higher than that of the treatment with nitric oxide alone and 20.98% higher than that of the treatment with clove essential oil alone, enhancing the disease resistance of the fruit. Therefore, the nitric oxide combined with clove essential oil through atomized fumigation can effectively maintain the quality of peaches during low-temperature storage, providing a theoretical basis for the development of quality control technologies for postharvest peaches.