اثر سه نوع علف كش پس رويشي در كنترل علف هاي هرز مزرعه ي آفتابگردان

Effects of Three Type Post Emergence Herbicides on Weed Control in Sunflower (Helianthus annum)

In order to study the effect of three types of post emergence herbicides on weed control in sunflower field a split-split plot experiment based on random complete block design with three replications was carried out. Treatments consisted of types of herbicides, assigned to main plot (a1= Gallant, a2= Na-boas, a3= Focus and control without weeding), application time to sub plot (b1=at 4-6 leaf stage, b2= at 8-10 leaf stage and b3= at 12-14 leaf stage) and rate of herbicide used, as sub-sub plot (c1= one liter per hectare and c2=two liter per hectare). Results showed that two liter per hectare of Gallant at 4 -6 leaf stage produced maximum leaf area index (5/09). Use of one liter per hectare at 4-6 leaf stage produced maximum seed yield (4961 kg/ha) and two liter per hectare of Gallant at 8-10 leaf stage and one liter per hectare of Gallant at 4-6 leaf stage resulted in maximum oil yields, 2315 and 2310 kg/ha, respectively. Use of one liter of focus at 4-6 leaf stage caused maximum increase in thousand-seed weight. The results of this experiment, in general, showed that use of Gallant at 4-6 leaf stage produced maximum leaf area index, seed number per head, seed and oil yields.