Studies On The Action And Its Mechanism Of Brassinnolide For Reducing The Phytotoxicity Of Ethametsulfuron On Rice

Ethametsulfuron is an excellent kind of herbicide in controlling the weeds in rape fields . Its biological activities is very high and its using quantity is low. It can control both singleleaf weeds and doubleleaves weeds in rape fields effectively . It is safe to human,domestic animal and environment.But it remains in soil long while rice is very sentitive to it. There often happen that phytotoxicity of ethametsulfuron on rice. Therefore,how to reduce the phytotoxicity of ethametsulfuron on rice is a worthy research. Using safeners is the first effective measure. For that,the influence of ethametsulfuron on the growth of different rice species were measured by cultivating it in water and soil. The action and its mechanism of brassinolide for reducing the phytotoxicity of ethametsulfuron on rice are studied on the base of former studies . The main results were listed as followed:1. The sentitives of five different rice species to ethametsulfuron were determined indoors. The results showed : ethametsulfuron has no influence on the rice sprout but ethametsulfuron had strong inhibition to the growth of rice and among the five rice species, xinxiangyou80 was the most sentitive species. The IC50 of height,rice fresh weight,root fresh weight of xinxiangyou80 to ethametsulfuron were 1.0962,1.0396,0.8099,0.7437mg.L-1(inwater)and 5.58,5.19,2.05,1.96ug.kg-1 respectively.2. The action of brassinolide for reducing the phytotoxicity of ethametsulfuron on rice was also determined by cultivating it in water and in soil in indoors. The results showed: brassinolide can remarkably reduce the phytotoxity of 0.1mg/L(in water)or 1.0ug/kg(in soil) ethametsulfuron on rice with the concentrations of 0.01-0.05mg/L BR.The 0.02mg/Lbrassinolide can reduce the phytotoxity of 0.01-2.0mg/L(in water) or0. 1-20.0ug/kg ethametsulfuron on rice with different extent.3. The mechanism of Brassinolide reducing the phytotoxicity of ethametsulfuron to rice was studied through the experiments on the influence of brassinolide to rice GSH content, GST activity and ALS activity in vitro and in vivo. The results showed that it was not very related to the GSH content and GST activity of rice and it was not direct but indirect action on the target enzyme of ALS.