The effect of mechanical and chemical weed control on the yield of onion (Allium cepa L.) seedlings cultivated fall in Hormozgan province.

In order to control weeds in transplanting onions in Hormozgan province, an experiment was conducted based on randomized complete block design with eight treatments and three replications in research farm of Agriculture Shamil district of Bandar Abbas city functions during 2015-2016. The treatments were: Control (no control), Oxyfluorfen (Goal) (EC%24) at 0.48 Kg a.i.ha-1, Sethoxydim (Nabu-s) (EC%12.5) at 0.375 kg ai.ha-1, Haloxyfop-R methyl ester (Gallant Super) (EC%10.8) at 0.81 Kg a.i.ha-1, Oxadiazon (Ronstar) (EC%48) at 1.44 Kg a.i.ha-1, Chlorthal dimethyl (dacthal) (WP%75) at 6 Kg a.i.ha-1, Ioxynil (Totril) (EC%22.5) at 0.45 Kg a.i.ha-1 and weeding (control weeds growing in all periods). The results showed that the density, dry weight of weeds and yield of onion was affected by treatments. Mechanical methods (weeding) in between treatments the highest effect on the density, dry weight of weeds and yield of onion was. So that the yield of onion increased at a rate of 5.50 tons.ha-1. Among the herbicides, herbicide oxyfluorfen (2 to 4 leaf stage of weeds) after mechanical method have the greatest impact on the density, dry weight of weeds and yield of onion accounted. As weed density and dry weight, by 65.2, 63.1% respectively, and yield of onion as much as by 509% increased performance. In total, herbicide efficacy in controlling weeds oxyflorfen and Ioxynil, C. album L., A. retroflexus, P. oleracea, M. sylvestris L. and C. rotundus L. was good. Chlorthal dimethyl on A. retroflexus and C. rotundus L., Oxadiazon on M. sylvestris L., A. retroflexus, and C. rotundus L. weed control and herbicide Haloxyfop-R methyl ester, P. oleracea and C. album L. and C. rotundus L. was good. In first grade mechanical methods (weeding) with good control of weeds and the highest yield of onion best treatment was experimental and oxyflorfen in the second grade herbicide and another herbicide Oxadiazon and Ioxynil is recommended in the Hormozgan province.