Objectives This paper discussed the effects of sulfur content in soil and flue-cured tobacco on the combustion and related indexes, trying to find out the appropriate sulfur content range for production of best flavor in flue-cured tobacco in Qujing area, Yunnan Province.

Methods From 2009 to 2011, 3507 soil and tobacco samples were collected in 9 tobacco planting counties of Qujing area, Yunnan Province. The available sulfur content in soil and the contents of sulfur, potassium and chlorine in tobacco leaves were analyzed. The relationship between the soil sulfur content and the contents of sulfur, potassium, chlorine in leaves, and the relationship between soil available sulfur content with the potassium and chlorine ratio and organic potassium index in tobacco leaves were calculated.

Results 1) The soil available sulfur contents in Qujing tobacco-growing areas were not uniform. Both the soil available sulfur contents and the tobacco leaf chlorine contents were significantly different among surveyed sites. 2) With the increasing of soil available sulfur content, the sulfur content of tobacco leaves increased, showing an extremely significant and positive correlation (P < 0.01). 3) Leaf potassium content and organic potassium index were significantly affected by leaf sulfur content. With the increase of sulfur content in tobacco leaves, the potassium content and organic potassium index of tobacco leaf increased first and then decreased. 4) The leaf sulfur contents affected the leaf chlorine contents. With the increase of sulfur content in tobacco leaves, the chlorine content of tobacco leaves decreased first and then increased.

Conclusions To maintain a high content of potassium content and appropriate chlorine content in tobacco leaves, the optimal range of sulfur content in soil is 3.84–48.53 mg/kg, and the appropriate chlorine content in tobacco leaves is 0.3%–0.6% in Qujing tobacco-growing areas.