In order to understand the effects of nitrogen form on key enzyme activity involved in nitrogen metabolism and grain protein content of speciality wheat cultivars, pot experiments were carried out at experimental station of Henan Agricultural University during 2000～2002. Soil containing 9.8 g/kg organic matter, 0.986 g/kg total N, 25.43 mg/kg olsen-p and 259 mg/kg NH_4OAc-K was used in the experiments. 18kg of sieved soil was placed in each 30cm×40cm pot. Three cultivars were used in experiments including Y...