In order to understand the mechanism of the effect of different forms of nitrogen on photosynthesis and spike development in wheat cultivars with specialized end-uses. Pot experiments were carried out at Henan Agricultural University Research Station 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. 18 kg of sieved soil was placed in each 30 cm×40 cm pot. Cultivars used in experiments were Yumai 34 (a str...