Effects of Nitrogen Fertilizer Reduction on Growth and Nitrogen Use Efficiency of Flue-cured Tobacco

【Objective】The effects of nitrogen fertilizer reduction on the growth and development, nutrient utilization, yield and quality of flue-cured tobacco were studied, and the feasibility of nitrogen fertilizer reduction was preliminarily clarified, which provided a theoretical basis for the sustainable production of flue-cured tobacco.【Method】Five treatments were set up, including no fertilization (control), conventional nitrogen application, 10% reduction of nitrogen fertilizer, 20% reduction of nitrogen fertilizer and 30% reduction of nitrogen fertilizer. The agronomic traits, economic traits, chemical composition and fertilizer utilization rate of tobacco plants in each treatment were compared and analyzed.【Result】An appropriate amount of nitrogen fertilizer reduction could shorten the growth period of flue-cured tobacco, and significantly increased the plant height, effective leaf number and maximum leaf width. In terms of chemical composition of tobacco leaves, the indexes of reducing sugar content, total nitrogen content and nicotine content of flue-cured tobacco leaves treated with nitrogen fertilizer reduction by 10% were all within the requirements of conventional chemical composition indexes of high-quality flue-cured tobacco in Yunnan. In terms of appearance quality of tobacco leaves, the color of flue-cured tobacco leaves treated with nitrogen fertilizer reduction of 10% and 20% was orange, the structure was loose or still loose, the oil was sufficient, and the appearance quality of tobacco leaves was better. In terms of nitrogen nutrient distribution, the nitrogen content of each part of tobacco plants showed the rule of leaf > stem > root, and the nitrogen content of tobacco leaves was significantly increased under the treatment of 10% nitrogen reduction. In terms of nitrogen use efficiency, after reducing nitrogen application by 10% and 20%, the nitrogen fertilizer utilization rate, agronomic efficiency and partial productivity of nitrogen fertilizer increased by 10.15%, 9.31%, 3.66%, 5.22%, 5.22%, 8.72%, respectively. After reducing nitrogen application by 30%, there was no significant difference between nitrogen fertilizer utilization rate and conventional nitrogen application rate. In terms of economic traits, the yield and output value of flue-cured tobacco increased by 6.47% and 16.18% after reducing nitrogen fertilizer by 10%.【Conclusion】The reduction of nitrogen fertilizer by 10% and 20% significantly affected the agronomic traits, nutrient distribution, chemical composition and economic traits of tobacco plants, however, the reduction of nitrogen fertilizer by 30% had no significant effect on the agronomic traits and economic traits of tobacco plants. The appropriate reduction of nitrogen fertilizer application promoted the growth of flue-cured tobacco, and improved the yield and quality as well as fertilizer utilization rate of flue-cured tobacco.