Effect of Integrated Weed Management (Chemical and Mechanical) on Grain Yield of Corn Hybrid S.C 700 under Shoushtar Conditions

In order to study the effects of mechanical and chemical methods of weed control in corn hybrid S.C700, a field experiment was conducted during 2009-2010. The experiment was a randomized complete block with four replications. Treatments were consisted of eleven combinations of mechanical (using cultivator) and chemical control with Ultim (Nicosulfuron+Rimsulfuron), Lumax (Mesotrione+S-metolacholor+Terbuthylazine) and Atrazin (Gesaprim) plus Lasso (Alachlor). Treatment included: Lumax+once cultivation, once cultivation, Atrazin plus Lasso+once cultivation, Ultim+once cultivation, Lumax+twice cultivation, twice cultivation, Atrazin plus Lasso+twice cultivation, Ultim+ twice cultivation, Lumax, Atrazin plus Lasso, Ultim and two control treatments, consisted un-weeded and complete control of weeds. Herbicides were used about 28 days after emergence. Results indicated that the highest weed control (after complete control weeds) was in treatment with two times application of cultivator plus Ultim herbicide. Treatments with two and one time application of cultivator plus Ultim herbicide and two times application of cultivator plus Lumax herbicide had not significant differences. In these treatments, grain yield increased other than free control of weeds respectively, 60.7%, 56.2% and 54.9%. Higher grain yield in these treatments was due to higher number kernels per ear and thousand kernel weight. Although the highest grain yield was in treatment with two times application of cultivator plus Ultim herbicide, but, because of probable increase of make mechanical damage on crop in time of frequent use of practice specially on extended areas, use of one times application of cultivator+Ultim herbicide was recommended. One and two times application of cultivator plus Ultim herbicide had not significant differences