The effect of chemical control of Echinochloa crus- galli weed at different growth stages on oil seed sunflower (Helianthus annus cv. Urofloure) yield

In order to study the effect of chemical control of Echinochloa crus- galli in different growth stages and determine the best herbicide application time and amount on the yield of oil-seed sunflower cv. Urofloure, an experiment was conducted at Agricultural and Natural Resources Research stations of Khoy region as split-split plot based on a randomized complete block design with three replications in 2006. Factors comprised of herbicide type as main factor (Haloxyfop-ethoxyethyl, Setoxydim and cycloxydim along with a control), herbicide application time as the sub-factor (4-6, 8-0 and 12-14 leaf stages) and herbicide dosage as the sub-sub factor (1 l.haP -1 Pand 2 l.haP -1 P). The measured traits were number of seeds per plant, weigh of thousand seeds, seed yield and oil yield. Results showed that maximum weight of thousand seeds was obtained by application of one litre per hectare Cycloxydim at 4–6 leaf stage. Application of one litre per hectare Haloxy fop-ethoxyethyl at 4–6 leaf stage resulted in maximum seed yield (4961 kg.haP -1 P). Also, the maximum oil yield was obtained with application of 2 litre Haloxy fop-ethoxyethyl at 8–10 leaf stage and one litre Haloxy fop-ethoxyethyl at 4–6 leaf stage (2315 and 2310 kg.ha,P -1 P respectively). Based on the results, Haloxy fop-ethoxyethyl application at 4–6 leaf stage caused maximum number of seeds per plant and the highest oil and seed yield. Haloxyfop ethoxyethyl was also better than other treatments in weed control.