Analysis of Routine Chemical Components and Safety of Flue-cured Tobacco Leaves under Organic Cultivation in Different Ecological Regions of Yunnan Province

Conventional chemical composition and security features of organic flue-cured tobacco leaves from eight different planting areas in Yunnan province were analyzed based on the data from 2011 to2012. There was a higher variation in conventional chemical composition of flue-cured tobacco leaves among different ecological areas(CV was between 8. 65% —22. 79%). Four tobacco leave types were grouped according to the regional characteristics. Down stalk tobacco leaves agreed with the standard; middle and upper stalk tobacco leaves had higher water soluble total sugar content and sugar alkali ratio,but lower total nitrogen,potassium content and alkali nitrogen ratio,with less harmony. The contents of heavy metals,lead,cadmium,arsenic,mercury,chromium were below the standard limit,and no pesticide residues were detected,so the security of tobacco leaves could be concluded. A reference was provided for establishing scientific organic flue-cured tobacco planting techniques. It was suggested that appropriately raising the level of nitrogen and potassium supply during the later period of tobacco organic cultivation wasnecessary to satisfy the demands of key nutrients for tobacco growing and improve the conventional chemical composition harmony of organic tobacco leaves.