Abstract: In order to study the influence mechanism of different forms of nitrogen (NO-3-N and NH+4-N) on the growth and development of plants under Cd stress, the contents of soluble protein, MDA, H2O2, O·-2, SOD, POD, and CAT activifices were measured and analyzed with Potamogeton crispusunder L. turions as the experimental material. The results showed that after adding Cd, the root, stems, and leaves of Potamogeton crispusunder L. were significantly stressed, while both NO-3-N and NH+4-N alleviated the stress. Also, compared with NH+4-N+Cd group, the contents of O·-2, H2O2 and MDA in NO-3-N+Cd group were lower associated with the activities of SOD, POD and CAT. NO-3-N had a more significant positive role in alleviating Cd stress to Potamogeton crispusunder L. By comparing the antioxidant system enzymatic activities of different organs of Potamogeton crispusunder L., the order of sensitivity to Cd stress was as follows: root> leaf> stem.

Key words: Potamogeton crispus L., Cd stress, NO-3, NH+4, influence