Effects of nitrogen application on carbon and nitrogen accumulation at different leaf positions of Yun tobacco 87

Carbon and nitrogen accumulation at different leaf positions of flue－cured tobacco was studied under different nitrogen conditions in order to explore effects of nitrogen application on carbon and nitrogen balance of different leaf positions. Results showed that the total nitrogen content decreased with the drop of leaf position firstly，then rose with the further drop of leaf position in A treatment（N 97.5 kg/hm2） and B treatment （N 112.5 kg/hm2）. The total nitrogen content of B treatment was significantly higher than that of A treatment at low leaf position，but the trend was reversed at high leaf position. The carbon content was significantly higher from the first leaf position to the 7th leaf position than that of other leaf positions. The carbon content decreased significantly or extremely with the drop of leaf position from the 8th leaf position to the 16th leaf position. The carbon/nitrogen（C/N）was the highest in cutters，secondly low leaf positions，the lowest content was at upper leaf positions. The C/N rose significantly in upper leaves with the drop of leaf position. There was no significant difference among cutters but the C/N decreased with the drop of leaf position in low leaves. The C/N in B treatment was significantly higher than that in A treatment in upper leaves and cutters near upper leaves but the trend in low leaves and cutters near low leaves was reversed. The conclusion suggested that the total nitrogen content，carbon content and C/N at different leaf positions in B treatment were more consistent with high grade leaf of flue－cured than those in A treatment.