Assessment of Herbicide Persistence and Phytotoxicity of Some Herbicides Used in Mazandaran Province on Rice (Oryza sativa)

To stimulate persistence of herbicides and their phytotoxicity,an experiment was conducted in randomized completely block design in a factorial arrangement with 3 replications at Weed Science Research Department of Iranian Research Institute of Plant Protection. Factors were type of herbicide at three levels (idosulfuron mesosulfuron (Chevalier)), metsulfuron methyl sulfosulfuron (Total) and Trifluraline (Treflan)), herbicide dose at seven levels (0, 5, 15, 25, 40, 100 and 150 percent of recommended doses) and soil type at two levels (from two different fields). The experiment soils were prepared from two regions of Mazandaran province and after transporting to Tehran, herbicide doses were treated in the soils with Simulators sprayer. Rice seedlings were planted in the pots that treated with herbicides. After thirty days, the seedlings were harvested and shoot fresh weight and root and shoot lenght were recorded. The results showed that the residue of all herbicides have negative effects on seedlings in both soils and increased with increasing the herbicide dose. Idosulfuron mesosulfuron had the highest negative impact on fresh weight, root length and shoot length of rice seedlings. The results of this investigation demonstrated that the studied herbicides used in rotational crops with rice have the potential capability of damage to rice plants and the possibility of decreased yield.