engleski

Weed control in winter wheat as affected by tillage and post-emergence herbicides

Field experiments were conducted in north- eastern part of Croatia to evaluate the impact of tillage systems in combination with low rates of post-emergence herbicides on weed density, weed dry biomass and grain yield of winter wheat under winter wheat-soybean cropping system. The treatments comprised of two tillage systems, including conventional tillage with mouldboard ploughing (CT) and reduced tillage with disk harrowing (RT), while four herbicide treatments (g a. i. ha-1) were: triasulfuron+chlortoluron (9.75 + 1027), prosulfocarb (2400), prosulfocarb plus triasulfuron (2400+7), pinoxaden plus triasulfuron (30+8) and untreated controls. Weed density and weed dry biomass were affected by year, tillage systems and weed management. The main weed was Apera spica-venti with greater shoots density m-2 of 43.7 in the wet 2007-08 compared to 26.1 shoots in the drier season of 2008-09 that made up 76-82% of total weed density, on average. In a two year average, CT tillage systems provided better suppressing of weed biomass (66.8 g m-2) than RT tillage (114.95 g m-2) with significant differences. All herbicide treatments with prosulfocarb or pinoxaden ensured a high level of A. spica-venti control (97-98%). When prosulfokarb was applied alone it brought an unsatisfactory control of Viola arvensis, Matricaria inodora and Papaver rhoeas, while as the combination with triasulfuron gave a consistent control of the mentioned and other annual broad-leaved weeds. Across years and tillage systems, the best total weed control was achieved with herbicide combinations of prosulfocarb plus triasulfuron (98%), followed by pinoxaden plus triasulfuron (97%), tank mixture of triasulfuron + chlortoluron (94%) and prosulfocarb (91%). In a two-year average, no significant differences in crop yield were revealed between tillage systems and herbicide treatments that ranged from 7817 kg to 8006 kg ha-1. The average yield increase ensured by herbicides was 6% and 15% in conventional and reduced tillage systems, respectively, compared to yields from weedy control plots.

Winter wheat ; tillage systems ; herbicides ; weed density ; weed dry biomass ; crop yield

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