A pot study was conducted outside the greenhouse at Bu-Ali Sina University, Hamedan, Iran in 2022. For each of the 22 herbicides tested, a dose-response experiment, applying zero, 1/16, 1/8, 1/4, 1/2, and 1 × labeled dose, was conducted. Soil- and foliar-applied herbicides were used after sowing the seeds and at the 3-4 leaf stage of quinoa, respectively. Quinoa had the highest sensitivity to acetochlor and linuron. Using one-eighth of their labeled dose, no seedlings could grow. Approximately, 2, 4, and 7% of the labeled dose of acetochlor or 3, 5, and 9% of the labeled dose of linuron were required to reduce 10, 50, and 90% in fresh:dry weight ratio, respectively. The application of 1/16, 1/8, and 1/4 × labeled dose of trifluralin, oxyfluorfen, bentazon, phenmedipham+desmedipham+ethofumesate, clomazone, clopyralid, chloridazone, ioxynil, tribenuron-methyl, metribuzin, pendimethalin, nicosulfuron, sulfosulfuron, and bispyribac-sodium caused a 10% reduction in fresh:dry weight ratio of quinoa. To reduce the fresh:dry weight ratio of quinoa by 10%, it needed using half to about the complete labeled dose of sethoxydim, haloxyfop-r-methyl, triflusulfuron-methyl, and imazethapyr. A loss of 10% quinoa fresh-to-dry weight would be achieved by using 1.78 and 1.56 times the labeled doses of pinoxaden and clodinafop-propargyl, respectively. As a recommendation, the efficacy of selected (pinoxaden and clodinafop-propargyl) and promising herbicides (sethoxydim, haloxyfop-r-methyl, triflusulfuron-methyl, and imazethapyr) should be evaluated under field conditions from the prospects of quinoa yield and weed control.
