Abstract: To study the effects of different topping periods and the number of leaves on the tobacco leaves on improving the quality of the upper leaves of burley tobacco, and determine the optimal topping period and the number of leaves on the tobacco leaves, plot trials were conducted in the core tobacco area of burley tobacco in Jianshi county, Enshi prefecture, Hubei province. The results showed that the combined measures of different topping periods and the number of leaves remaining on the tobacco can directly affect the economic benefits of tobacco leaves and the distribution of nicotine content in tobacco plants. At the early stage of budding, keeping 8 and 6 leaves of tobacco leaves can significantly increase the output value of tobacco leaves, but the nicotine content in the upper part and the branches is high, and the internal chemical components are not coordinated. In the initial flowering stage, 15%~20% flower topping tobacco, the yield of keeping 4 leaves was lower than that of the early budding with 8 and 6 leaves, but the nicotine content in each part was appropriate and the internal chemical composition was coordinated. Comprehensive analysis shows that under the treatment of keeping 4 leaves of tobacco leaves in the early flowering stage, the economic benefits of tobacco leaves are better, the nicotine content is appropriate, and the industrial availability of upper tobacco is stronger.

Key words: burley tobacco, topping, number of leaves left, upper tobacco, quality