In order to study the effect of light intensity on the physiological characteristics of flue cured tobacco and effect of its regulation on the senescence of flue-cured tobacco,this paper carried out experiments by taking flue-cured tobacco Yunyan 87 as material and setting 5 intensity gradient:100%(T1),85%(T2),76%(T3),68%(T4)and 58%(T5) natural lights,and investigated the effect of light intensity on photosynthetic pigment,soluble protein and MDA content and changes in SOD,pod,cat antioxidant enzyme activit...