Abstract:

In order to meet the application demand of cigarette industry for yellow sun-cured tobacco materials in flue-cured cigarettes, the best topping method and topping time of yellow sun-cured tobacco in Dehong of Yunnan Province was clarified, and the effects of four topping methods (T₁ pinching the top, T₂ topping at bud stage, T₃ topping at early flowering stage, T₄ topping at flowering period) on the agronomic, economic, grade structure and intrinsic chemical quality of ‘Yunshai 1’ yellow sun-cured tobacco were studied. The results showed that the comprehensive performance of T₁ treatment was the best, followed by T₃ treatment. And the chemical components content of upper and middle tobacco could meet the requirements of high-quality tobacco leaves and the needs of cigarette industry. The chemical quality comprehensive performance of T₂ and T₃ treatment were better. The nicotine content of upper leaves was over 2% in four treatments, in which T₂ treatment was the best, over 2.5%, and T₃ treatment was nearly 2.5%. The nicotine content of middle leaves was more than 2.4%, and that of T₂ and T₃ treatments were close to 3%. So it is suggested that the best method for yellow sun-cured tobacco in Dehong is to top at early flowering stage, followed by topping at bud stage. The best time for topping is in mid-to-late March, or about 110 days after transplanting.

Key words: yellow sun-cured tobacco, ‘Yunshai-1’, topping methods, grade structure, quality of tobacco leaf