Abstract:The effects of different N sources (ammonium sulfate,glutamate, glycine and lysine) on rice (Oryza sativa L.)seedlings grown in high temperature(35 ～ 37℃ during lighting period and 30 ～ 33℃ during dark) and sterile sand culture was studied The dry matter of plants grown 20 days with ammonium as sole N source was significantly lower than that grown with amino acids, and also slightly lower than that grown with free N (control), indicating ammonium toxicity The total N of plant cultured with amino acids was similar to that with ammonium, and was 50% higher than control Compared with the control, root GOT and GPT activity of roots and leaves of plants grown with ammonium (N 10 or 500 mg/L) increased to twice, perhaps relative to ammonium toxicity Grown for 15 days in low N concentration (N 10 mg /L), GOT activity in leaves of plants with glutamate as sole N source significantly increased The activity of GPT in glycine fed plant roots and leaves and glutamate fed plant leaves significantly increased, but GOT activity in lysine fed plant leaves decreased Treated with high N concentration (N 500 mg /L) for 6 h, the activity of GPT was 5.7, 9.4, and 1.9 times control in roots, respectively, for glycine , glutamate and lysine treated plants, and was 1.8, 2.3 and 1.4 times control in leaves, respectively These results indicated that rice seedlings grown under higher temperature were able to take up organic nitrogen