Taking aseptic seedlings of P.crispus as the experimental material,the effect of different concentrations of Cu²⁺ (0,1, 2,4,8,12 μmol/L) on the metabolism of polyamine(PAs) and reactive oxygen were investigated.With the increasing of Cu²⁺ concentration,the results indicated that: (1) Superoxide dismutase(SOD) activity increased markedly,while the activities of peroxidase(POD) and catalase(CAT) increased progressively followed by a decline.(2) The generation rate of O₂^-· and the content of H₂O₂ and MDA increased,while soluble protein content decreased.(3) Free putrescine(Put) content first enhanced and then reduced notably.However,the content of free spermidine(Spd) decreased gradually and spermine(Spm) increased significantly.Therefore,the ratio of free (Spd+ Spm)/Put promptly increased under high concentrations of Cu²⁺ stress.The changes of total PAs content were similar to those on free PAs.Perchloric acid soluble conjugated(PS-conjugated) Put and Spm changed in the same pattern as free PAs.While PS-conjugated Spd content increased slightly.In addition,the content of perchloric acid insoluble bound(PIS-bound) Put and Spd first increased and then decreased,but they were still higher than those in the control.Moreover, PIS-bound Spm content declined.(4) With the increase of Cu²⁺ concentration,the activity of arginine decarboxylase (ADC) sharply decreased after a transient increase,while the activity of ornithine decarboxylase(ODC) did not change significantly.Polyamine oxidase(PAO) and diamine oxidase(DAO) activities increased gradually,followed by a decrease.Our results suggested that Cu²⁺ stress induced obvious oxidative damage on aseptic seedlings of P.crispus.The up-regulation of antioxidant enzymes activities and Spm content,the changes of Put into Spd and Spm as well as the conversion between different forms of polyamines played a key role in the adaptation mechanism of aseptic seedlings of P.crispus under Cu²⁺ stress.