Effect of coated and uncoated normal urea on carbon and nitrogen metabolism in summer maize

Zhengdan958 was used as material to study the differences in carbon and nitrogen metabolism in summer maize exerted by two types of nitrogen fertilizers, coated urea and normal uncoated urea, in successive two years. The results showed that total sugar content in leaves, sheathes and stems was improved by both nitrogen applications. The improvement effect was greater before 12-leaf stage in normal uncoated urea treatment, while greater after silking in coated urea (CU) treatment. Nitrogen content in leaves, sheathes and stems were significantly improved by nitrogen application, and the effect of CU was greater. Ratio of carbon to nitrogen in sheathes and stems were decreased by nitrogen application, and the effect of CU was greater. Nitrogen harvest index was decreased by nitrogen application, and the decreasing extent in CU treatment was bigger. Translocation of carbon in leaves, sheathes and stems occurred in dough to maturity, and translocation of nitrogen in leaves, sheathes and stems mainly occurred in dough to maturity and silking to dough respectively, and the translocation amounts of carbon and nitrogen in CU treatment were bigger. The results showed that CU could improve carbon and nitrogen metabolism in summer maize.