Study of the structure of weed population of wheat fields affected by cultivar and tillage

This research project was conducted to study the population and biodiversity indices of weed species in wheat fields in Qazvin province/Iran during the 2015/2016 cropping season. A networking sampling method was employed to study the weed species in three wheat production systems of no-tillage-rainfed (low input), no-tillage-irrigated (intermediate input), and moldboard-tillage (high input)-irrigated systems. Sampling was conducted at two growing stages (Tillering and end of stemming). The species diversity of Simpson, Shannon-Weiner, Margalof richness, Menhinic and dominance index were determined by genus and species. The dominance index in dry farming fields (0.9245) was higher than irrigated farms, and in irrigated farms with moldboard tillage (0.7451) was higher than no-tillage irrigated fields (0.6664). The Shannon index in low input farms (2.9693) was more than high input (1.5230) treatment and in high input farms was more than intermediate input (1.4346) treatment. The highest Margalof richness index was obtained from dry farming system (1.8516) while the lowest was observed in no-till fields (0.7432). The species richness index in low input farms was more than high input and in high input was more than intermediate input (with conservative tillage) fields. The results of this project demonstrated that no-till production system is associated with less weed species and diversity in wheat fields.