为明确不同施氮量在烟叶成熟时期对上、中部烟叶生理特性的影响，2012年在河南省许昌市以烤烟品种“中烟100”为研究对象，打顶后每隔5 d取样，测定了不同成熟时期、不同部位的鲜烟叶在氮肥梯度下的叶绿素含量、硝酸还原酶活性、可溶性蛋白质及游离氨基酸含量.结果表明，不同施氮量对上、中部叶成熟过程的氮代谢活动影响较大.在上部烟叶逐渐成熟过程中，不同的施氮量对烟叶中的叶绿素、可溶性蛋白质含量影响不显著，对硝酸还原酶活性影响显著，对游离氨基酸含量影响极显著；在中部烟叶逐渐成熟过程中，不同施氮量对可溶性蛋白质含量影响不显著，对硝酸还原酶活性影响显著，对叶绿素、游离氨基酸含量影响均极显著.可见，只有适量施用氮肥，才能生产出优质烟叶,本研究中以施氮量45 kg/hm2最佳.
Effects of nitrogen application rate on physiological characteristics of flue-cured tobacco leaves at the maturing stage were studied by surveying chlorophyll content, nitrate reductase(NR) activity, soluble protein content and free amino acid content of fresh leaves of Zhongyan 100, a variety planted in Xuchang city of Henan Province, from different positions and in different periods every 5 days, form April to September, 2012. The results showed that during the gradually mature process of tobacco, effects of nitrogen application rate on soluble protein content and chlorophyll content of the upper tobacco leaves were not significant, but it was significant on NR activity and free amino acids content. The effect of nitrogen application rate on soluble protein content of the middle tobacco leaves were not significant, but it was significant on NR activity, chlorophyll content and free amino acids content. Only appropriate amount of nitrogen application could produce high quality tobacco leaves. The treatment of 45 kg/hm2 pure nitrogen was the best.