| In order to clarify the control effect and optimum dosage of clomazone on common ragweed, the inhibitive effect of clomazone on seed germination of common ragweed, Ambrosia artemisiifolia was evaluated in laboratory and outdoor studies. Ten days after incubation, common ragweed seeds in different treatments were took out to survey the germination rate, shoot length, root length and fresh weight. The results showed that there was a parabolic relationship between clomazone dosages and germination rates, all inhibitive rates were almost between 20% and 40%, and there were significant differences among different treatments. 1.62 g/hm2 solution showed the highest inhibitive rate, which was 37.3%. The inhibitive rates of shoot length, root length and fresh weight increased significantly with the increase of clomazone dosage, and there were significant differences among different treatments in the inhibitive rates. The inhibitive rates of clomazone at 1.62 g/hm2 on shoot length, root length and fresh weight were 80.5%, 79.8% and 74.1%, respectively, which did not differ from the higher dosages. Based on the results of present experiment, it is suggested that the control effects increased significantly with the increasing dosage of clomazone in an optimum dosage range. But, the control effects decreased along with the increasing dosage when the dosage exceeds the optimum range. Thus, the optimum dosage of clomazone was 1.62 g/hm2 for field application. |
