Effect of N Application Rate on Nitrate-N Content in Corn plant and Yield of Corn

[Objective] This study aimed to discuss the effect of N application rate on nitrate-nitrogen(NO3——N) content and yield of corn in different growing stages.[Method] In the plot field test,the effect of applying N at 0,150,300,450 kg/hm2 on NO3——N content in corn plant and the yield of corn were studied.[Result] The NO3——N content in each leaf part of corn plant showed a downward tendency along with delay of corn growing stage as a whole.In seedling,jointing and filling stage,the NO3——N content of in the treatment without N fertilizer was lower than that in each treatments of N application.And the relativity of the NO3——N content in each leaf part of corn plant and N application rate had great difference in these 3 growth stages.The NO3——N content in the third and sixth leaf part of corn plant in these 3 growth stages showed such performance as that NO3——N in the third leaf part was higher than that in the sixth leaf part in seedling stage and that in the sixth leaf part was higher than that in the third leaf part in jointing and filling.The NO3——N content in the sheath was obviously higher than that in the leaf in these 3 growth stages and its increasing became slow when N application was higher than 300 kg/hm2.[Conclusion] N application could significantly increase the grain and straw yield of corn and the recommendatory N application rate for corn should be controlled at 300 kg/hm2 under the experimental condition.