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Purpose Nitrogen fertilizer plays an important role in crop yield and quality.To satisfy the nitrogen demaud,farmers use very large amounts of nitrogen fertilizers to obtain maximum yields.These high fertilizer inputs lead to marked deterioration in soil and cause secondary salinization in Chinese greenhouse.The excessively accumulated salinity in soil of the greenhouse were mainly composed of anion NO3-,accounting for 67％ to 76％ of total anions and limited the growth of plants significantly.Polyamines are low-molecular-weight aliphatic amines that are not only involved in the regulation of plant developmental and physiological processes,but also play important roles in modulating the defense response of plants to diverse environmental stresses,especially salt stress.But most of salt stresses regarded NaCl as means of research,while the effects of polyamines on plant growth under excess NO3-was seldomly investigated.