3. Assessment of weed infestation in a biological field during the conversion period in central Northern Bulgaria

The study was conducted during the 2013-2015 period at the Institute of Forage Crops – Pleven.
Weed infestation in the biological field during the conversion period was represented by a mixed type of weed infestation according to the type of edificator: winter common wheat (Triticum aestivum L.) – annual monocotyledons (Echinochloa crus-galli (L.) Beauv. and Setaria spp), annual dicotyledonous (Galium aparine L., Chenopodium album L., Lamium amplexicaule L., Papaver rhoeas L. and Sinapis arvensis L.); perennial monocotyledonous (Sorghum halepensis (L.) Pers.); perennial dicotyledenous (Convolvulus arvensis L., Cirsium arvense (L.) Scop. and Sonchus arvensis L.); spring forage peas (Pisum sativum L.) – annual monocotyledonous (Avena fatua L., Echinochloa crus-galli (L.) Beauv. and Setaria spp), annual dicotyledenous (Chenopodium album L., Rumex crispus L., Sinapis arvensis L. ); perennial monocotyledonous (Sorghum halepensis (L.) Pers.); perennial dicotyledonous (Convolvulus arvensis L., Cirsium arvense (L.) Scop. and Sonchus arvensis L.).
Weed species diversity (D), intrapopulation distrbution – (EH) and evenness (Eр) of the weeds in the biological field during the conversion period were influenced slightly by the edificatory type and dynamics of the agrometeorological conditions.