تاثير روشهاي خاكورزي بر پويايي جمعيت علف هاي هرز در مزرعه پنبه (Gossypium hirsutum L.) كشت شده بعد از كلزا (Brassica napus )

Effects of tillage systems on weeds population dynamics in cotton (Gossypium hirsutum L.) followed by rapeseed (Brassica napus)

In order to study the effects of different tillage systems on density and diversity of weeds in cotton followed by rapeseed, this research was conducted in Randomized Complete Block design with three replications in Gorgan in 2005. Treatments were different tillage methods such as no-tillage (plant in cutting residue), plowing plus disk (as a conventional method), chisel plus disk (as low tillage) and two time disking (as a minimum tillage). Weeds and rapeseed seedlings that germinated in cotton were counted three times (in two leave stage, squaring and flowering stages of cotton) in each treatment. The results showed that weed density and weeds species were affected by tillage methods significantly. Perennial weeds specially Cyperus rotundus L. were more observed in no tillage treatment but annual weeds for example Physalis alkekengi L. , Solanum nigrum L. and Amaranthus spp. were more dominant in common tillage. In low tillage treatments (Chisel and Disk) there was both annual and perennial weeds .Germination of rapeseed in no-tillage, plow, chisel and disk was more than common tillage. On view of yield, there was no significant difference between low tillage systems and common tillage, therefore we can use low tillage system instead of conventional tillage, however we have to find proper methods for weed control in this system.