Background. Reduced tillage systems enable a reduction in expenditure on energy and improve the economic effectiveness of production, but, among other things, they are favourable for weed infestation of a plantation. The aim of the study was to determine the effect of tillage systems and methods of treatment on the reduction in weed matter, and to determine the phytotoxic effect of herbicides applied on the damage of plants of yellow lupine and its yield. Material and methods. The study results come from a field experiment set up in a split-plot design in three replications. The studied factors included: I – two tillage systems – conventional and reduced: II – five methods of weed control: 1) control plot – mechanical treatment, 2) chemical treatment – spraying with preparation Afalon Dyspersyjny 450 SC (linuron) directly after sowing, 3) mechanical and chemical treatment [Metron 700 SL (metamitron)], 4) chemical treatment Afalon Dyspersyjny 450 SC + Metron 700 SL, 5) chemical treatment Afalon Dyspersyjny 450 SC + Metron 700 SL + Fusilade Forte 150 EC (fluazifop-p-butyl). Results. The assessment of weed infestation was carried out two weeks after applying the last herbicide treatment as well as directly before harvesting the yellow lupine seeds. The air dry mass of weeds was lower after conventional tillage than after reduced tillage. The lowest quantity of weeds was recorded after applying conventional tillage and three herbicides, and the highest quantity was on the control plot. The highest plant damage was observed after applying three herbicides. The seed yield of yellow lupine was significantly modified by tillage systems, methods of weed control and weather conditions occurring in particular growing seasons. Conclusion. Weed control on plots with herbicide treatment contributed to an increase in the seed yield of yellow lupine compared with the control plot. Moreover, response to herbicide damages in yellow lupine significantly depended on the applied cultivation methods, causing slight damages to disappear with the passing time.

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