Studies on the influence of different nitrogen forms and key enzyme of flue-cured tobacco nitrogen metabolism NR,GS activity,total N and the content of nicotine was studied showed that NR and GS activity of T2 treatment (applied NH 4-N singlely) was the highest after transplanting 30 days.The content of all the nitrogen of T1 (applied NO 3-N singlely) was increased 53.40%, T2 was increased 60.23%,T3 (NO 3-N∶NH 4-N=1∶1) was increased 23.75%in 30-76 days after transplanting.The content of nicotine in m...