Effect of nitrogen rates on the physiology characteristic and the chemistry quality of flue-cured tobacco

The field experiment is made to study the effect of nitrogen rates on the physiology characteristic and the chemistry quality of flue-cured tobacco.The results showed that in the maturing and resettling stage of flue-cured tobacco,when the soil is the lack of nitrogen or the nitrogen excessive,the root system vigor,the SOD activeness and photosynthesis speed decreased markedly,the content of MDA increased obviously,the difference in the content of PRO elevates was no significant,in the vigorous growing and squaring stage of flue-cured tobacco,but all these indexes had increased obviously with the increasing of nitrogen;in the resettling stage of flue-cured tobacco,the content of total nitrogen 、nicotine and protein in the middle leaf and the upside leaf increased significantly,but the content of total sugar and reducing sugar decreased obviously,the sugar alkali 、NIT/NIC and SUR/NIT of flue-cured tobacco is more reasonable when it is processed by mild nitrogen rates with the increasing of nitrogen.