Effects of Potassium Nutrition on Carbon Metabolism and Quality of Flue-cured Tobacco

[Objective]The research aimed to study the effects of potassium on carbon metabolism and quality of flue-cure tobacco.[Method] In this experiment,different potassium(K2O) levels treatment(0,90,180,270 and 360 kg/hm2) was done under the same levels of nitrogen and phosphorus in field(N 90 kg/hm2,P2O5 180 kg/hm2).[Result]The main results showed that the activities of invertase and amylase at the middle and later stage of tobacco growth increased with appropriate application of potassium,which was also beneficial for the transformation from nitrogen metabolism to carbon metabolism at suitable time.After 30 and 45 d of flue-cured tobacco transplant,the content of total soluble sugar,reducing sugar and starch in leaves decreased with the increase application of potassium at the early stage of tobacco,while increased with the increasing application of potassium levels at the middle and later stage after 60,75 and 90 d of flue-cured tobacco transplant,indicating the application of potassium would be better for carbon accumulation at the later stage but not at the early stage of tobacco.[Conclusion] The appropriate quantity of adding potassium was 270 kg/hm2,at this experimental condition,the yield of flue-cured tobacco was highest and the quality was much more coordinate.