Mechanisms of High Maize Yield and Nitrogen Use Efficiency under Optimized Nitrogen Management

Maize grain yield is reduced by nitrogen deficiency.Excessive nitrogen fertilizer can’t increase yield of maize，but it decreases nitrogen use efficiency and causes serious environmental problems.Reasonable nitrogen fertilization can ensure adequate nitrogen uptake at different growth stages of maize，which is beneficial to the maximum yield.Studies on effects of different nitrogen supply levels on morphological and physiological processes of maize from domestic and foreign scholars in recent years were reviewed.Reasons that nitrogen deficiency resulted production reduce and excessive nitrogen supply couldn’t increase production were discussed from root development，leaf morphology and photosynthesis，and ear development，which provided theoretical basis for rational management of nitrogen fertilizer and selection of nitrogen efficient maize varieties.