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1- Department of Agrotechnology, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran2PhD Scholar, Weed Science, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Queensland, Gatton 4343, Australia
2- Department of Crop Production and Plant Breeding, College of Agriculture, Shiraz University, Shiraz 71444165186, Iran;
3- Department of Soil Science, College of Agriculture, Shiraz University, Shiraz 71444165186, Iran
4- Department of Agrotechnology, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
5- The University of Queensland , b.chauhan@uq.edu.au
Abstract:   (169 Views)
To investigate the response of soil microbial populations to glyphosate and sulfosulfuron, a factorial-experiment was conducted at Shiraz University, Iran. The factors included different herbicides and dose rates (glyphosate at 0, 540, 1080, and 4320 g a.e. ha-1 and sulfosulfuron at 0, 12.5, 25, and 50 g a.i. ha-1), and time of measurements (4, 15, 45, and 65 days after herbicides spray). The results showed that microbial respiration, microbial biomass carbon and metabolic quotient were highest for glyphosate 1080 g a.e. ha-1 at 4 days after herbicide application. Dehydrogenase activity had a decreasing trend in all herbicide treatments in comparison with the control treatment in all measuring times except 4 days after spraying. There was no significant difference in dehydrogenase activity between herbicide treatments. The effect of sulfosulfuron on microbial respiration and metabolic quotient was not significant whereas time and its interaction with herbicide dose rate affected these two variables significantly. Generally, all the measured indices for sulfosulfuron and glyphosate treatments reduced with time after herbicide application. Sulfosulfuron 50 g ha-1 and glyphosate 4320 g ha-1 had the lowest amounts of aerobic heterotrophic bacteria after 65 days, decreased by 23.7% and 50% compared with the control. Our results demonstrate that the effects of herbicides on soil microbial communities are strongly related to the herbicide dose and the time after herbicide spray. In conclusions, the herbicides at doses more than the recommended doses showed inhibitory effects on soil microbial communities in the alkaline soil.
     
Article Type: Original Research | Subject: Soil Chemistry, Fertility, Plant nutrition
Received: 2019/03/8 | Accepted: 2020/11/15

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