Effects of Nitrogen Application on Nitrogen Dynamic Changes and Nitrogen Use Efficiency in Maize

Nitrogen accumulation reached the peak around 45 days after silking stage and high population was helpful to nitrogen accumulation.Total N content of the plant was positively correlated with yield and it got closer in higher density.Grain nitrogen content and nitrogen harvest index were significantly positively correlated with yield in higher density.Nitrogen application high ratio in silking stage was beneficial to N accumulation in leaf and ear,as well nitrogen translocation in stem and sheath,nitrogen application high ratio in earlier stage delayed nitrogen metabolism.Nitrogen uptake peak was from silking stage to 15 days after silking stage,nitrogen uptake rate increased in later growth stages under nitrogen application high ratio in silking stage and moved forward in higher population.It was advantaged for nitrogen fertilizer efficiency on condition that nitrogen application was moved backward.Accumulating too much nitrogen in earlier stages had inhibition on nitrogen uptake in later periods.