A study was conducted on the effect of different nitrogen forms on the activity of GS,SS,SPS and content of nicotine and reduced carbohydrate in flue_cured tobacco leaves through filed experiment.The result showed that GS of T2 remained a relatively high level from 85 d after transplanting to the end.The content of nicotine was 1.2 times that of T1,1.1times that of T3 on 91 d after transplanting,the content of reduced carbohydrate was 0.4 times that of T1,0.6 times that of T3. T1 was more suitable for the ...