Abstract: By means of a system of nutrient solution culture, an apple rootstock, Malus robusta Rehd. was used to study effects of foliar application of exogenous salicylic acid (SA) on reactive oxygen species metabolism under root-zone hypoxia stress. The results showed that the content of malonaldehyde(MDA), superoxide radical(O2), hydrogen peroxide(H2O2)and glutathione (GSH) and activities of antioxidant enzymes under root-zone hypoxia stress were higher than the control, however, the level of ascorbic acid (AsA) were decreased. Exogenous SA significantly decreased the content of O2, MDA and GSH, increased the activities of superoxide dismutase(SOD), peroxidase(POD), ascorbate peroxidase(APX)and glutathione reductase (GR)under hypoxia stress. It was proposed that exogenous SA as a chemical activator could induce resistance, reduce production of reactive oxygen species, raise the activities of anti-oxidative enzymes, and decrease the membrane lipid peroxidation, therefore it alleviated the damage degree of hypoxia stress of Malus robusta Rehd.

Key words: salicylic acid, Malus robusta Rehd., hypoxia stress, antioxidant enzymes