ABSTRACT
2Nitric oxide (NO) is a key signaling molecule mediating various developmental and physiological activities in horticultural crops at pre- as well as during postharvest. NO has an antagonistic relationship with ethylene production through its ability to suppress the activities of ethylene biosynthesis enzymes. Endogenous NO production has been reported as a plant strategy to defer the climacteric phase of many horticultural crops, reduce yellowing, chlorophyll degradation of vegetables, and increase the vase life of various flowering plants. NO fumigation has been found more effective in delaying the fruit ripening and shelf/vase life extension of fruits, vegetables as well as cut flowers. However, its more marked effects have been found in nonclimacteric fruits as compared to climacteric ones. Nevertheless, owing to the volatile nature of NO and reactive oxygen species toxicity, its super optimal concentrations can result in harmful effects; therefore, precise monitoring of their threshold levels is very important for maintaining the anticipated beneficial effects needed for the desirable ripening modulation, shelf/vase life extension of fruits, vegetables, and flowers, respectively.
