Abstract: We aimed to study the effects of multiple sprays with amino oligosaccharide (AOS) during fruit development on wound healing in harvested muskmelons. The muskmelon plants and fruits (cv. Manao) were sprayed with AOS at 2 mL/L for four times at the four stages (young fruit stage, early stage of enlargement, late stage of enlargement and mature stage) of fruit development. The effect of AOS sprays on the mass loss and disease index of harvested fruits during wound healing was evaluated. The formation of closing layer was observed on the wounds. Related metabolic enzyme activities were determined. AOS sprays effectively reduced the mass loss and disease index of wounded fruits inoculated with Trichothecium roseum during wound healing. On day 7, the mass loss and disease index of the treated group were 28.64% and 32.00% lower than those of the control group, respectively. The sprays promoted the deposition of suberin polyphenolics and lignin at wound sites, and the cell layer of suberin polyphenolics and lignin deposited was 22.70% and 25.07% thicker than those in the control group on the 5th day of healing. The sprays also increased phenylalanine ammonia lyase activity, and enhanced the contents of total phenols, flavonoids and lignin. In addition, the sprays significantly raised H2O2 content and peroxidase activity at wound sites. Taken together, preharvest multiple sprays with AOS could promote wound healing in harvested muskmelons by activating phenylpropane metabolism, and increasing H2O2 content and peroxidase activity.

Key words: amino oligosaccharide; preharvest sprays; muskmelons; wound healing; phenylpropane metabolism