Study of critical concentration and symptoms in tobacco phytotoxicity caused by six soil residual herbicides

The critical concentration and symptoms in tobacco phytotoxicity caused by 6 soil residual herbicides including chlorimuron-ethyl,tribenuron-ethyl,nicosulfuron,atrazine,prometryne and fomesafen were determined by pot experiment.The results showed that the growth of tobacco roots,stems and leaves were inhibited in varying degree by the 6 soil residual herbicides.The symptoms in tobacco phytotoxicity caused by chlorimuron-ethyl,tribenuron-ethyl and nicosulfuron were chronic,uneasy to recover and long durationwhile atrazine,prometryne and fomesafen were acute,it was easy to recover from mild phytotoxicity or quicklywithered and died in severe cases.The critical concentration causing tobacco phytotoxicity of chlorimuron-ethyl,tribenuron-ethyl,nicosulfuron,atrazine,prometryne and fomesafen were 5.31×10-3,2.79×10-3,1.05×10-2,3.35×10-3,2.00×10-3 and 1.11×10-4 mg/kg.