关键词: 烤烟, 氮素形态, 生长发育, 养分累积, 化学成分

Abstract: Using the Yunyan 87 as experimental materials, a field experiment was conducted by setting three experiment groups of different NH₄⁺/NO₃^- ratio（3∶7, 5∶5 and 7∶3） to systematically study the effects of different NH₄⁺/NO₃^- ratio on the growth （agronomic trait, biomass）,nutrient accumulation（the content and accumulation of nitrogen, phosphorus and potassium）and chemical components of tobacco in Enshi city. The results showed that there were no significant difference for agronomic trait and biomass among these three groups during the early, middle and late period of tobacco. Likewise, at topping and mature period, there were no obvious difference for the content and accumulation of nitrogen, phosphorus and potassium among these groups. With the increase of the ratio of NH₄⁺/NO₃^-, the content of total sugar and reducing sugar in the upper leaves decreased, while the content of total nitrogen and nicotine increased, while the content of potassium and chlorine did not change significantly. The application of different ratio of NH₄⁺/NO₃^- had no obvious effect on the growth and nutrient accumulation of tobacco plants, but had some effects on the chemical composition of upper tobacco leaves, among which the coordination of chemical composition was the best when the ratio of NH₄⁺/NO₃^- was 3∶7.

Key words: tobacco, nitrogen forms, growth, nutrient accumulation, chemical components