Formation of weed community in pea (Pisum sativum L.) as affected by herbicide and crop rotationKształtowanie się zbiorowisk chwastów grochu siewnego (Pisum sativum L.) pod wpływem herbicydu i następstwa roślin

Summary This paper presents the results obtained in the crop rotation experiment carried out in the years 2008–2010. It concerns weed infestation of pea (Venus variety) cultivated in six-field crop rotation: sugar beet – maize – spring barley – pea – winter oilseed rape – winter wheat, and in monoculture since 1993. Two levels of crop protection were compared: level 0 – no chemical protection, and H – with the protection of herbicide (linuron) applied after sowing at 1.5 kg/ha doses. The species composition and the number of weeds were determined at the development stage of 2–4 leaves of pea and prior to the mechanical cultivation using a frame with an area of 0.25 m 2 . On the objects without chemical protection in crop rotation and in monoculture the number of weeds amounted to 237 plants/m 2 and 614 plants/m 2 , respectively. The applied herbicide reduced the number of weeds in the crop rotation by 87.8% and by 82.5% in the monoculture. Regardless of the chosen method of crop protection, the following weed species dominated: Chenopodium album, Thlaspi arvense and Capsella bursa-pastoris. In monocultural cultivation Lycopsis arvensis, Polygonum convolvulus and also perennial weeds occurred as well.