We investigated the effects of nitric oxide (NO) fumigation on fruit ripening, chilling injury, and quality of Japanese plums cv. 'Amber Jewel'. Commercially mature fruit were fumigated with 0, 5, 10, and 20 µL L-1 NO gas at 20 °C for 2 h. Post-fumigation, fruit were either allowed to ripen at 21 ± 1 °C or were stored at 0 °C for 5, 6, and 7 weeks followed by ripening for 5 d at 21 ± 1 °C. NO-fumigation, irrespective of concentration applied, significantly (P ≤ 0.5) suppressed the respiration and ethylene production rates during fruit ripening at 21 ± 1 °C. At 21 ± 1 °C, the delay in fruit ripening caused by NO-fumigation was evident from the restricted skin colour changes and retarded fruit softening in fumigated fruit. NO treatments (10 and 20 µL L-1) delayed the decrease in titratable acidity (TA) without a significant (P ≤ 0.5) effect on soluble solids concentration (SSC) during fruit ripening. During 5, 6, and 7 weeks of storage at 0 °C, NO-fumigation was effective towards restricting changes in the fruit ripening related parameters, skin colour, firmness, and TA. The individual sugars (fructose, glucose, sucrose, and sorbitol) profiles of NO-fumigated fruit were significantly different from non-fumigated fruit after cold storage and ripening at 21 ± 1 °C. CI symptoms, manifested in the form of flesh browning and translucency, were significantly lower in NO-fumigated fruit as compared to non-fumigated fruit after 5, 6, and 7 weeks storage and followed by ripening for 5 d at 21 ± 1 °C. NO-fumigation was effective in reducing the decay incidence in plum fruit during ripening without storage and after cold storage at 0 °C for 5, 6, and 7 weeks. In conclusion, the postharvest exposure of 'Amber Jewel' plums to NO gas (10 µL L-1) delayed fruit ripening by 3-4 d at 21 ± 1 °C, and also alleviated chilling injury symptoms during cold storage at 0 °C for 6 weeks.
