To investigate the effect of weekening light intensity on the growth and development,yield and yield structure of flue-cured tobacco under the condition of high altitude.A field experiment was carried out to investigate the effects of shading on the growth,development,yield and composition of yield of tobacco.The re-sults indicated that under shading,the growing progress of tobacco plants delayed,the length and width of to-bacco leaves increased,the plant height increased,the diameter of stem and lateral root decreased,the number of lateral roots with a diameter in excess of 2 mm also decrease...