Study on Tolerance of Four Setaria spp.to Mesotrione·Atrazine 550 g/L SC

The tolerant difference of Setaria glauca(L.) Beauv.,Setaria geniculata(Lam.) Beauv.,Setaria viridis(L.) Beauv.and Setaria faberri Herrm.to mesotrione·atrazine 550 g/L SC was investigated in the bioassay method.The results showed that there was a dramatical difference of tolerance to mesotrione·atrazine 550 g/L SC among the four Setaria spp.species.Under the same dosage,Setaria faberri Herrm.was the most tolerant weed,Setaria viridis(L.) Beauv.was the second one and Setaria glauca(L.) Beauv.was the most sensitive species.Under the dosage of 825 g a.i./hm2,the inhibiting rate of mesotrione·atrazine 550 g/L to the 1 leaf-age Setaria faberri Herrm.was only 17.2%,while Setaria glauca(L.) Beauv.,Setaria geniculata(Lam.) Beauv and Setaria viridis(L.) Beauv.which were at the 1 leaf-age were reached to 99.3%,99.7% and 99.8% respectively.The inhibiting rate of mesotrione·atrazine 550 g/L to the fresh weight of four Setaria spp.decreased as the leaf age of the four Setaria spp.increasing.The inhibiting rate of mesotrione·atrazine 550 g/L SC to the Setaria spp.increased more significantly than that of atrazine and mesotrione which were used alone at each leaf stages of four Setaria spp.weeds.