Effects of Nitrogen Fertilizer on Maize Carbon Translocation in the Condition of Straw Returning

The pot experiment was taken with two factors of nitrogen fertilizer and straw returning,ten replications,and four nitrogen levels(N0,N1,N2 and N3)in this study.Nitrogen amounts were 0,75,150,300 kg hm-2.The results showed that,with the increasing of nitrogen amount,the carbon from photosynthesis always increased no matter straw returning to field or not.When nitrogen amount was 300 kg hm-2,the carbon from photosynthesis and yield were the most highest in the condition of straw returning.The contribution of the carbon from photosynthesis to grains reached the maximum value under N0.But it reached the minimum value under JN1.JN2 was the best for the carbon translocation in maize.The carbon translocation decreased with the further increasing of nitrogen amount.The value of carbon translocation under JN0 was minimum.When nitrogen amount were N2 and N3,ear weights without added straw into soil were 134.3 g and 167.5 g,respectively.But they were 154.5 g and176.7 g with added straw into soil,respectively.The variation of 100-grain weight had a similar trend to that of Ear weight.