The effects of arbuscular mycorrhizal fungi(AMF),Glomus mosseae,on oxygen radical scavenging system of tomato under salt stress were studied in potted culture experiments.The response of tomato(Lycopersicon esculentum L.) cultivar Zhongza 9 seedlings with AMF inoculation and control to salt stress(0,0.5 and 1.0% NaCl solution,respectively) was investigated.The results showed that the salt stress significantly reduced the dry matter content of roots,stems and leaves,and also the leaf area as compared with the control treatment.However,arbuscular mycorrhizal-inoculated(AM) significantly improved the dry matter and the leaf area in the salt-stressed plants.The effect of AMF on dry matter was more pronounced in aerial biomass than in root biomass which might be due to AM colonization.The activities of SOD,POD,ASA-POD,and CAT in leaves and roots of mycorrhizal and non-mycorrhizal treatment of tomato plants were increased and had different rules under different NaCl concentrations(solution of 0,0.5 and 1% NaCl),but all enzymes had a rise in the beginning of treatment under salt stress conditions.The AMF did not change the rule of tomato itself under salt stress,but AMF increased these enzyme activities in different levels.The AMF treatment significantly increased SOD,POD and ASA-POD activities in leaves and roots,whereas it had little effects on CAT in root.O2 production rate and MDA content in leaves increased continuously,which showed a positive line correlation with salt stress concentration.O2 production rate and MDA content in tomato plants significantly decreased by AM treatment compared with nonmycorrhizal treatment.In conclusion,AM could alleviate the growth limitations imposed by saline conditions,and thereby play a very important role in promoting plant growth under salt stress in tomato. The effects of arbuscular mycorrhizal fungi (AMF), Glomus mosseae, on oxygen radical scavenging system of tomato under salt stress were studied in potted culture experiments. The response of tomato (Lycopersicon esculentum L.) cultivar Zhongza 9 seedlings with AMF inoculation and control to salt stress (0,0.5 and 1.0% NaCl solution, respectively) was investigated. The results showed that the salt stress significantly reduced the dry matter content of roots, stems and leaves, and also the leaf area as compared with the control treatment. , significantly improved the dry matter and the leaf area in the salt-stressed plants. The effect of AMF on dry matter was more pronounced in aerial biomass than in root biomass which might be due to AM colonization. activities of SOD, POD, ASA-POD, and CAT in leaves and roots of mycorrhizal and non-mycorrhizal treatment of tomato plants were increased and had different rules under different NaCl concentrations (solution o f 0, 0.5 and 1% NaCl), but all enzymes had a rise in the beginning of treatment under salt stress conditions. AMF did not change the rule of tomato itself under salt stress, but AMF increased these enzyme activities in different levels. The AMF treatment increased highly SOD, POD and ASA-POD activities in leaves and roots, yet it had little effects on CAT in root. 02 production rate and MDA content in leaves increased continuously, which showed a positive line correlation with salt stress concentration. O2 production rate and MDA content in tomato plants significantly decreased by AM treatment compared with nonmycorrhizal treatment. In conclusion, AM could alleviate the growth limitations imposed by saline conditions, and thereby play a very important role in promoting plant growth under salt stress in tomato.