The effects of nitrogen on dynamic change of nitrate reductase activity(NRA) and grain pro-tein content during growth development periods of wheat and relationship between NRA andgrain protein content were investigated by the experiments of applying nitrogen amount in 1991 1993. The results are shown as follow:In growth development stages,NRA in leaf is maximumround about blossom,NRA in grain and NRA in glurne are both maximum in day 15 21 behidblossom.Applying nitrogen may increases NRA in growth develop...