Effect of Night time Temperature Increase on the Physicochemical Properties and Aroma Precursors of Flue-cured Tobacco in High-altitude Region in Yunnan Province

In this study,taking 'Yunyan100' as sample,we systematically studied the effect of the increased night temperature on the physicochemical properties,microelement and content of main aromatic compounds in flue-cured tobacco produced in the high-altitude area of Baoshan,during their growth duration. The results showed: (1)Leaf width and simple leaf weight in all parts of tobacco significantly increased, while length and stem ratio of upper leaves greatly decreased and thickness of middle and lower leaves increased largely.(2)The difference of total sugar and reducing sugar in all processed tobacco decreased in different degrees and the content of nicotine and chlorine cut largely,yet the content of potassium significantly increased and the total nitrogen content grew in different degrees than the control groups.(3) Cu and Fe contents of upper leaves greatly decreased, while Zn and Mn significantly increased;Fe contents of middle leaves greatly decreased, while Zn,Mn significantly increased;Cu,Fe and Mn contents of lower leaves greatly decreased, while Fe significantly increased.(4) The lutein,beta carotene,chlorogenic acid and rutin contents of lower leaves greatly increased,while the middle leaves content of malonic acid and malic acid notably dropped and the content of palmitic acid and oleic acid remarkably increased. As a result, the increased night temperature significantly improved the physical characteristics, the coordination of chemical components, and industrial utilization in flue-cured tobaccos in high altitude areas in Yunnan.