| After topping, the effect of exogenous substances T1～T7 on the leaf tissue structure and the content of potassium and nicotine of upper leaves of flue-cured tobacco was studied in the field experiment.The results showed that exogenous substances could promote the upper leaf area increase, and accommodated the thickness of palisade tissues, spongy tissues and the cell density of palisade tissues dynamic changes, and decreased leaf thickness, loosen the tissue, and increased the potassium content, while reduced nicotine content.In general, T1, T4 and T7 treatments were optimized in improving the leaf tissue structure and incresing potassium content. |