Title: The study of the effect of Vejin herbicide on control of weeds in the rice ratooning cultivation
Author: Farzin Pouramir
Abstract: Weed control is one of the most important problems in rice ratooning. In this study, the efficacy of the new herbicide (Bispyribac-sodium, SC 12.5%) in controlling rice weeds in the ratooning system was investigated. This experiment was carried out based on a randomized complete block design with three replications in the research farm of the Rice Research Institute of Iran in 2019. The investigated treatments included doses of 100, 150 and 200 % of the recommended dosage of Vejin herbicide (250 ml / ha), Cheaf (250 ml / ha), Stamdox (Propanil + Bensulfuron-Methyl, 3 kg/ha), Basagran (Bentazon + MCPA, 2.5 l/ha), Nominee (250 ml / ha), Clean-weed (100 ml / ha), Council (triafamone + ethoxysulfuron, 125 g/ha) and weedy control. The results showed that the application of Vejin herbicide up to twice the recommended dose did not lead to any toxicity on the rice plant. Six weeks after treatment, Vejin (100 and 200% of recommended dose), Clean-weed and Nominee with 20, 26, 23, and 26 g / m2 had the lowest amount of barnyard grass biomass, respectively, which were 78, 71, 75, and 71% lower than weedy control. Among the treatments, Cheaf herbicide with 97 g / m2 had the highest and Vejin (200% of recommended dose), with 21 g had the lowest amount of bulrush biomass, which decreased by 35% and 86%, respectively, compared to the control treatment. The difference between herbicide treatments was significant in terms of paddy yield. The highest rice yield with 1683 kg/ha was observed in the Clean-weed herbicide treatment and the lowest value was observed in the weedy control with 710 kg/ha. Among the studied doses of Vejin herbicide, the dose of 150% with 1604 kg/ha had a significantly higher yield compared to the doses of 200 and 100% (1347 and 1326 kg/ha, respectively). All three doses of this herbicide increased the yield of paddy by 87 to 126% compared to the weedy control. The results of this experiment showed that the application of 150% of the recommended dose of Vejin herbicide can lead to optimal control of barnyard grass and bulrush weeds in the rice ratooning system without causing harmful effects on rice plants, and thus significantly increase rice yield (1604 kg/ha) in compared to weedy control (710 kg/ha). Therefore, this herbicide can be used as a suitable alternative or supplement to the old herbicides used in rice ratooning systems.
Keywords: Barnyard grass, Bulrush, Paddy field, Herbicide
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