Studies on Heat Shock Inhibiting the Browning of Fresh-cut Burdock Effects of Burdock Oligosaccharide on Physiological and Biochemical Features of Cucumber Seedlings Studies on Heat Shock Inhibiting the Browning of Fresh-cut Burdock Induction of Volatile Organic Compounds of Lycopersicon esculentum Mill. and Its Resistance to Botrytis cinerea Pers. by Burdock Oligosaccharide