Effects of nitrogen application and remaining leaves and their interactions on yield and quality of flue-cured tobacco NC297

In order to promoting the coordination and optimization of yield and quality of NC297, the effect of nitrogen application and remained leaves as well as their interaction on physical characteristics, chemical composition and economic characters were studied. It was indicated that leaf length, leaf width, leaf thickness, leaf area and single leaf weight showed the same trend of increasing up with the nitrogen applied in the range of 7.5–60 kg/hm2, while stem rate and dry weight per unit leaf area first decreased and then increased. Nicotine and total nitrogen content significantly increased with increasing nitrogen application and dropped down with the increasing of remained leaves. With the increasing of nitrogen and remained leaves, the yields of tobacco increased constantly, while the output value, average price, proportion of superior and moderate tobacco first increased and then decreased. Nitrogen application showed the largest impact on indexes concerning physical characteristics, chemical compositions and economic characters aside from reducing sugar and sugar/nicotine ratio, followed by the remained leaves and the interaction between nitrogen application and remained leaves showed the smallest impact. According to the study, the appropriate nitrogen amount and the suitable numbers of remained leaves were 30 kg/hm2 and 20–23, respectively.