Agricultural Research Journal

Seeds of isoproturon resistant Phalaris minor were collected from wheat fields and field experiments were conducted during winter season of 2012 and 2013. The biotype was found resistant to clodinafop-propargyl, fenoxaprop-pethyl and also showed cross resistance to pinoxaden. Mesosulfuron + iodosulfuron and sulfosulfuron provided 65 and 90 per cent control of the weed, respectively. Metribuzin recorded above 90 per cent weed control during both the years. Plants sprayed with metribuzin showed a sharp decrease in chlorophyll fluorescence (Fv/Fm ratio) of about 65 per cent as compared to control after 24 hours of spray even when there were no visible symptoms of herbicide injury. By this time, reduction in Fv/Fm ratio was less than 10 per cent for plants treated with ACCase and ALS inhibitors. At 15 days after spray, Fv/Fm ratio decreased by 11 to 13 and 23 to 30 per cent as compared to control for ACCase and ALS inhibitors, respectively.