Evaluation of effect of different herbicides and cultivation on weed control and yield of Onion (Allium cepa L.)

This study was conducted in 2007-2008 and 2008-2009 growing seasons at Agricultural Research Center of Safiabad. Experimental design was randomized complete blocks with 15 treatments at 4 replications. Herbicide treatments were: 1-Oxadiargyl at 1.5lit/ha +Haloxyfop-R-methyl at 0.75lit/ha postemergence 2- Oxyfluorfen at 1.5lit/ha at two phases at 0.75lit/ha postemergence 3- Oxyfluorfen at 1.5lit/ha postemergence 4-Ioxynil at 3lit/ha+ Haloxyfop-R-methyl at 0.75lit/ha postemergence 5-Oxadiargyl at 1.5lit/ha+Haloxyfop-R-methyl at 0.75lit/ha postemergence+ cultivation 6-Oxyfluorfen at 1.5lit/ha at two phases at 0.75lit/ha postemergence+cultivation 7- Oxyfluorfen at 1.5lit/ha postemergence+ cultivation 8-Ioxynil at 3lit/ha+Haloxyfop-R-methyl at 0.75lit/ha postemergence+cultivation 9- Oxadiargyl at 1.5lit/ha postemergence 10-Haloxyfop ethoxy ethyl at 2lit/ha postemergence 11-Oxyfluorfen at 1.5lit/ha preemergence 12- Ioxynil at 3lit/ha postemergence 13-cultivation 14-Weed free check 15-Weedy check. Number and dry weight of weeds per m2 at two stages: 1-Post spraying and cultivation 2- The end of growth season and onion yield were measured .Evaluation of phytotoxicity effect of different herbicides showed that Oxyfluorfen at 1.5lit/ha preemergence injured emergence of onion plant 50%. Results of experiment showed that there was a significant difference among herbicide treatments for number of wild chicory and mallow and total of weeds at post spraying.So that there was a significant difference among herbicide treatments for number of mallow and total of weeds at the end of growth season. So that there was a significant difference among herbicide treatments for dry weight of wild chicory and mallow and total of weeds at post spraying and the end of growth season. There was a significant difference among herbicides treatments for onion yield. Results of means comparisons of characteristics showed that application of Oxyfluorfen at 1.5lit/ha at two phases at 0.75lit/ha postemergence + cultivation was the best treatment for weed control and yield increase in onion fields.