Iranian Society of Weed Science Iranian Journal of Weed Science 1735-3548 12 2 2017 02 19 Study on Bioavailability of some Wheat Herbicides in Different Tillage Systems and their Impact on Corn Study on Bioavailability of some Wheat Herbicides in Different Tillage Systems and their Impact on Corn 121 131 113218 FA Satar Javid Weed Science, University of Tehran Hassan Alizadeh Weed Science, University of Tehran Mohammad Reza Jahansouz Weed Science, University of Tehran Farshid Nouralvandi Weed Science, University of Tehran Journal Article 2017 09 17 This experiment was conducted to study the residual effect of some wheat herbicides on following corn (<em>Zea mays </em>L<em>.</em>) crop under different tillage systems in Karaj province. Tillage treatments included: conventional tillage, minimum tillage and, no-tillage. Herbicide treatments were: 1- bromoxynil + MCPA (EC 40%) 1.5 lit/ha, 2- triasulfuron + dicamba (WG 70%) 150 gr/ha, 3- mesosulfuron-methyl + iodosulfuron-methyl-sodium (62 WG) 400 gr/ha, 4- metsulfuron methyl + sulfosulfuron (w/v %5+75WG) 36 gr/ha, 5- tribenuron methyl (EC 8%) + clodinafop propargyl (DF 75%) 20 gr/ha and 0.8 lit/ha respectively, as well as unweeded control (without herbicide). Soil sampling for bioassay tests made from surface layer (0-12.5 cm) and, sub-surface layer (12.5-25 cm). Bioassay experiment was conducted with Cress (<em>Lepidium sativum</em>) as a test plant and corn. Cress emergence percentage and cress and corn dry matter and height was assessed. Results indicated that herbicide bio- availability was depended on tillage system; in fact herbicide bio-availability was minimum in no-tillage systems. Triasulfuron + dicamba, mesosulfuron-methyl + iodosulfuron-methyl-sodium and metsulfuron methyl + sulfosulfuron were the most persistent herbicide based on bio-availability, respectively.  Therefore, these herbicides may damage the following corn crop in rotation although, corn was more tolerant to metsulfuron methyl + sulfosulfuron. On the other hand, the persistence of bromoxynil + MCPA and tribenuron methyl + clodinafop propargyl herbicides in the soil was negligible and damage seems unlikely by theses herbicide in rotation. This experiment was conducted to study the residual effect of some wheat herbicides on following corn (<em>Zea mays </em>L<em>.</em>) crop under different tillage systems in Karaj province. Tillage treatments included: conventional tillage, minimum tillage and, no-tillage. Herbicide treatments were: 1- bromoxynil + MCPA (EC 40%) 1.5 lit/ha, 2- triasulfuron + dicamba (WG 70%) 150 gr/ha, 3- mesosulfuron-methyl + iodosulfuron-methyl-sodium (62 WG) 400 gr/ha, 4- metsulfuron methyl + sulfosulfuron (w/v %5+75WG) 36 gr/ha, 5- tribenuron methyl (EC 8%) + clodinafop propargyl (DF 75%) 20 gr/ha and 0.8 lit/ha respectively, as well as unweeded control (without herbicide). Soil sampling for bioassay tests made from surface layer (0-12.5 cm) and, sub-surface layer (12.5-25 cm). Bioassay experiment was conducted with Cress (<em>Lepidium sativum</em>) as a test plant and corn. Cress emergence percentage and cress and corn dry matter and height was assessed. Results indicated that herbicide bio- availability was depended on tillage system; in fact herbicide bio-availability was minimum in no-tillage systems. Triasulfuron + dicamba, mesosulfuron-methyl + iodosulfuron-methyl-sodium and metsulfuron methyl + sulfosulfuron were the most persistent herbicide based on bio-availability, respectively.  Therefore, these herbicides may damage the following corn crop in rotation although, corn was more tolerant to metsulfuron methyl + sulfosulfuron. On the other hand, the persistence of bromoxynil + MCPA and tribenuron methyl + clodinafop propargyl herbicides in the soil was negligible and damage seems unlikely by theses herbicide in rotation. https://ijws.areeo.ac.ir/article_113218_dce531b5eccc4c26c3fe927d49fefec7.pdf