Bioassay And Rice Sensitivity Of Three Kinds Of Sulfonylurea Herbicide Residues In Soil

Chlorsulfuron , Metsulfuron and Ethametsulfuron are three kinds; of Sulfonylurea herbicides that have been registered for controlling several weeds in wheat or rape fields. However, residues of these herbicides can injure subsequent sensitive crops in some situation.A bioassay technique based on growth of pre-germinated com roots was used to establish the dose-effect curves and mathematic models of three kinds of Sulfonylurea herbicides in three kinds of soils. From the mathematic models, the EDio values, the herbicides concentration that the inhibition rate of corn roots reaches 10%, were estimated. The EDio levels of Chlorsulfuron are 0.7988, 1.1841 and 1.6655ng/g in loam soil, silt loam soil and clay loam soil, respectively. The EDio levels of Metsulfuron are 0.2385, 0.3860 and 0.3027ng/g in three soils, respectively. The EDio levels of Ethametsulfuron are 6.0706, 4.0532 and 5.5755ng/g. They can be used as minimum detectable amount of three kinds of herbicides in soils.Another experiment was designed to determine the sensitivity of rice seedling to three kinds of herbicides in a paddy soil (a kind ofloam soil). Through the inhibiting test of rice seedling roots, we find that the most sensitive herbicide is Metsulfuron, the ED|0 values of Chlorsulfuron Metsulfuron and Ethametsulfuro are 0.877,2.06 and 4.583 ng/g respectively. The result shows if the double recommendatory dose of these three herbicides were used in JiaXing paddy soil and base on the hafe-life of these herbicides in local soil , the subsequent rice seeding would not be injured.