以豫烟5号、豫烟7号和NC89为材料，研究氮素对不同品种烤烟叶片衰老、光合特性及产量和品质的影响.结果表明：增施氮素可显著增强烤烟叶片超氧化物歧化酶(SOD)活性，降低丙二醛(MDA)含量，提高叶绿素含量，增强光合性能，从而延缓烤烟叶片衰老.与豫烟5号和NC89相比，豫烟7号叶片叶绿素含量较低，光合性能较弱，SOD活性低，MDA含量高，叶片衰老较快.与60和75 kg·hm-2施N处理相比，45 kg·hm-2 施N处理的烟叶均价、产值、上等烟比例均最高，且化学品质指标较好，符合优质烟叶要求.表明不同品种烤烟衰老生理特性有明显差异；氮素营养对烤烟叶片衰老、产量和品质有明显的调节作用；适量施氮可提高烟叶品质，获得较高的经济效益.
Taking three flue-cured tobacco (Nicotiana tabacum L.) varieties Y5, Y7, and NC89 as test objects, this paper studied the effects of nitrogen fertilization on their leaf senescence, photosynthetic characteristics, yield, and quality. Increasing nitrogen supply increased the leaf superoxide dismutase (SOD) activity, chlorophyll content, and photosynthetic performance, and decreased the leaf malondialdehyde (MDA) content significantly. Accordingly, the leaf senescence was delayed. Compared with Y5 and NC89, variety Y7 had higher leaf MDA content and lower leaf SOD activity, chlorophyll content, and photosynthetic performance, and thus, its leaves senesced faster. High quality tobacco leaves with higher average price, gross value, superior leaves percentage, and reasonable chemical constituents were harvested under the application of 45 kg N·hm-2,compared with applying 60 and 75 kg N·hm-2. It was suggested that different flue-cured tobacco varieties had obvious differences in their leaf senescence physiological characteristics, and nitrogen fertilization played important roles in regulating their leaf senescence, yield, and quality. Appropriate nitrogen fertilization could improve the quality of tobacco leaves, and achieve higher economic benefits.