the effect of soil disturbance methods and weeds control on the density and distribution of cotton’s (gossypium hirsutum) weeds after wheat

to evaluate the effect of combined use of different soil tillage methods and weed control on cotton yield, a split plot experiment based on randomized complete block design was conducted at the city of boshruyeh in 2012. experiment factors were tillage method as main-plots with three levels, including conventional tillage, no-till system and minimum tillage; and different methods of weed control at 5 levels (the herbicide trifloxysulfuron sodium at 10, 15 and 20 g ha-1, as well as no weeding and hand hoeing) as sub-plots with four replications. the results showed weed density and weeds species were affected by tillage methods significantly. the methods of (no-till or less) conservation tillage than conventional tillage, increased density, narrow leaf weeds in broadleaf weeds while the density decreased. perennial weeds specially cynodon dactylon l. were more observed in no tillage treatment but annual weeds for example setaria spp, echinochloa crus gali l. , amaranthus sp.and chenopodium album l. were more dominant in common tillage. in low tillage treatments (chisel and disk) there was both annual and perennial weeds. conventional tillage was observed the most weed density decreased (narrow and broad-leaved) weeds in cotton field in used of dose of 20 g ha envok with sytvgyt and conservation tillage was next in rank.