effects of tillage systems on yield of cotton following canola in gorgan

the conservation system is one of the proper methods avoiding the loss of nutrients, soil erosion, and reduce production costs. this research was examined for studying the influences of tillage systems on the three cotton cultivars at karkandeh and hashm-abad stations in gorgan. the experiments were conducted in a randomized completely block design as split plot with three replications with five tillage systems (mould board plough, chisel, disc, strip and no tillage) as main plot and three cultivars (siokra324, zodrac-motagenez and cindoz 80) as sup-plot. the results showed that effects of tillage system was significant on yield. yield was more in chisel and disk (conservation tillage) by having more monopodial branch length, number of monopodial and sympodial branch, plant height and boll in plant than mould board plough (conventional tillage) and no-tillage system in all cultivars. the siokra324 cultivar had more yield due to having more boll in plant than two other cultivars. yield in no-tillage system was lower than conservation and conventional tillage but the grown plants in this system were smaller and had lower branching. thus population density can be increased for gaining higher yield from this system, and it is recommended to do complete experiments for studying the effects of various population densities in no tillage system and conservation tillage with the conclusive studies are replaced conventional tillage.