Effects of Nitric Oxide on Storage Quality and Microstructure of Seedless White Grape Stem

In order to study the effect of nitric oxide (NO) on the physicochemical quality, pigment accumulation and microstructure of thompson seedless grape during storage. The grapes were fumigated with 500 μL/L NO or air for 2 h and then stored at 0±0.5 ℃ for 25 days, afterwards the grapes were separately moved to simulated shelf conditions for 3 days at 8±0.5 ℃ and 20±0.5 ℃ at the same time. The results showed that NO significantly slowed down the weight loss of grape rachis and the increase of electrical conductivity, inhibited the degradation of chlorophyll and the accumulation of anthocyanin in grape rachis compared with the control group. NO reduced the quantity and strength of cracks on the surface of spine, but also helped to maintain the tightness of intercellular space arrangement, slowed down the depletion of inorganic matter in the xylem, thus reducing the degree of partial depressions in the tissues. Tissue staining analysis showed that NO maintained the volume of rachis epidermal cells, slowed down the cell wall thickening and corkification, in addition, inhibited the accumulation of brown matter in the epidermis. In conclusion, NO fumigation was conducive to maintaining the quality of grape rachis, delaying the browning by inhibiting chlorophyll degradation and anthocyanin accumulation, moreover, maintaining the integrity of the rachis microstructure.