Effect of herbicides and their tank mixture on weed dynamics and yield of zero- tilled wheat (Triticum aestivum) under rice (Oryza sativa)wheat cropping system of eastern Uttar Pradesh

An on-farm trial was conducted at Gorakhpur, Uttar Pradesh during the winter seasons of 201011 and 2011 12, to assess the efficacy of sulfosulfuron, Clodinofop, metribuzin, mesosulfuran + idosulfuron and tank mixture of sulfosulfuron with 2,4-D, metsulfuron and carfentrazone ethyle as well as clodinofop with metsulfuron in zero-tilled wheat [Triticum aestivum (L.) emend. Fiori & Paol.] crop. All herbicidal treatments reduced the weed density and weed dry weight significantly compared to weedy check. In general, tank-mix application of herbicides proved bet- ter than their alone application in suppressing weed number and dry weight. Highest grain yield (5.17 t/ha) and straw yield (5.79 t/ha) were recorded in weed-free plot, which was at par with clodinofop + metsulfuron (60+2.5 g a.i./ha). Uncontrolled growth of weeds caused 45.3% reduction in the crop yield compared to weed-free treatment. Tank-mix application of clodinofop with metsulfuron and sulfosulfuron with metsulfuron, carfentrazone ethyl and 2, 4-D proved better, showing an increase in grain yield of 14.7% than their alone application. Tank mix application of clodinofop with metsulfuron remaining at par with sulfosulfuron + carfentrazone ethyl significantly reduced the weed density and weed dry weight compared to rest of the herbicides tested. Tank-mix application of clodinofop + metsulfuron remaining at par with sulfosulfuron mix with either carfentrazone ethyl, metsulfuron or 2, 4-D was most effective in enhancing yield attributes, grain and straw yield. Highest net returns ( 33,660/ha) and benefit: cost ratio (2.91) were also obtained using clodinofop + metsulfuron. Application of metribuzin in spite of better weed-control efficiency recorded the lowest grain yield amongst the herbicides tested which was at par with mesosulfuron + idosulfuron.