Study on Weed Flora Change of Irrigated Wheat Fields of Savojbolagh and Shirvan Counties: 2000 to 2011

In order to determine changes in weed flora in wheat fields of Savojbolagh and Shirvan counties, the results of studies in 2000 and 2010 were compared. Based on the first study (2000) in Savojbolagh County, 57 species belong to 19 families and in Shirvan county 28 species belong to 13 families were detected. In second study (2010) in Savojbolagh County, 53 species belong to 19 families and in Shirvan county 53 species belong to 18 families were detected.Some species of flora were removed and some new species were added to the flora. Abundance index of some species were changed, some species lost their dominance and others became dominant. Any change in the dominance index due to changes in frequency, density, or both, can be related to many factors. In Savojbolagh dominance of many species including knotweed (Polygonum aviculare), bedstraw (Galium aparine), lepyrodiclis (Lepyrodiclis holosteoides). speedwell (Veronica camplypoda) and fumitory(Fumaria vaillantii) were due to increase in density but in Shirvan dominance of many species including common lambsquarters(Chenopodium album), hairy vetch(Vicia villosa), (Goldbachia laevigata) and Canada thistle (Circium arvense) were due to increase in density, except for knotweed (Polygonum aviculare) was due to increase in frequency. Any change in the abundance of grass weed species in wheat fields of Savojbolagh indicate that the management methods applied for these species have failed after a decade and winter wild oat (Avena ludviciana) and feral rye (Secale cereale) remain as the dominant grass weed species. Change in abundance index of broadleaf weed species in Savojbolagh and dominance of some species such as knotweed, lepyrodiclis and speedwell showed that change flora of broadleaf weeds was in response to weed management methods. Introduction of new species to the wheat fields of Shirvan was considerable. The management methods applied were clearly the reasons for the floral changes, we should now adopt new strategies to manage the new species.