This experiment studied the effect of potassium in carbon metabolism and quality of flue-cure tobacco by different potassium(K2O)levels treatment.The main results showed,the activities of invertase and amylase during the middle and later stage of tobacco growth increased with appropriate application of potassium nutrition.The carbohydrate content of leaves increased quickly after transplanting 60 days(squaring stage).The total soluble sugar content,reducing sugar content and starch content of leaves increas...