Effects of Nitric Oxide Fumigation On Postharvest Life, Chilling Injury, and Quality of Japanese Plums (Prunus salicina Lindell)

Short postharvest life and susceptibility to chilling injury (CI) limit marketability of Japanese plums in domestic and export markets. Nitric oxide (NO), a free radical gas, has been implicated in regulation of postharvest senescence in horticultural commodities. We aimed this research to extend postharvest life and alleviate CI of Japanese plums through NO fumigation. Therefore, commercially mature ‘Amber Jewel’ plums were fumigated with different levels of NO gas (0, 5, 10, and 20µL.L^-1) at 20°C for 2 hours. Post-treatment, fruit were either allowed to ripen at ambient conditions {21±1°C and 60±7% relative humidity (RH)} or were kept in cold storage (0°C and 86± 5% RH) for 7 weeks. At ambient conditions, NO fumigation, irrespective of concentration applied, significantly suppressed the respiration rate of fruit compared to the untreated fruit. Ethylene production in fruit exposed to 10 and 20µL.L^-1 NO was significantly lower than those treated with 0 and 5µL.L^-1 NO. The fruit quality evaluation at 3 day intervals (0, 3, 6, 9, and 12 days) during ripening at ambient conditions revealed that NO fumigation decreased the loss in flesh firmness and restricted the changes in skin color (Lightness, chroma, and hue angle) and titratable acidity without a significant effect on soluble solids concentration. During cold storage at 0°C, fruit quality was evaluated at 5, 6, and 7 weeks and after 5 days at ambient conditions (21±1°C and 60±7% RH) for each interval. NO fumigation was effective in reducing the CI symptoms, which appeared in the form of flesh browning and translucency, after 5 and 6 weeks of cold storage and followed by ripening for 5 days at 21±1°C. NO fumigation also retarded the changes in fruit ripening parameters such as skin color, firmness, and titratable acidity during storage and ripening. In conclusion, NO fumigation (10µL.L^-1) extended the postharvest life of ‘Amber Jewel’ plums to 12 days at ambient conditions against 9 days in untreated fruit, and also alleviated CI symptoms during cold storage at 0°C for 6 weeks. Our study shows that NO fumigation has potential to become a postharvest tool to increase the marketability of Japanese plums.