Dependence of soybean weed infestation on growing conditions in the Eastern Forest-Steppe of Ukraine

Abstract

Goal. To establish the species composition of weeds, their dominant role and determine the type and level of weediness of soybean crops for cultivation in a fixed nine-course stationary, fallow-crop-row rotation and in monoculture in the eastern part of the Forest-Steppe of Ukraine. Methods. The research was conducted by route surveys in field experiments. Results. According to the research of 2011—2017, 30 species of weeds and contaminants were found in soybean crops after winter wheat as forecrop in the stationary crop rotation (spring early and late were 60%, winter and biennial were 17%, perennial were 23%), and 18 species (spring early and late were 72%, wintering and biennial were 6%, perennial were 22%) were found for cultivation in monoculture. They belonged to 16 families, the families Asteraceae (9 species), Poaceae (5 species) and Polygonaceae (5 species) were the most represented. The main weeds in soybean crops in crop rotation and monoculture were Echinochloa crus-galli (L.) Roem. et Schult., Chenopodium album L., Cirsium arvense (L.) Scop. and Panicum miliaceum L. In addition to these weeds for growing soybeans in crop rotation were present Setaria glauca (L.) Beauv., Amaranthus retroflexus L., Solanum nigrum L., Polygonum lapathifolium L., Sonchus arvensis L., Convolvulus arvensis L., and in monoculture were Ambrosia artemisiifolia L. and Xanthium strumarium L. Xanthium strumarium L. was the most dominant in the monoculture (43%), and Setaria glauca (L.) Beauv was subdominant in crop rotation (57%), and Echinochloa crus-galli (L.) Roem. and Schult. was subdominant in monoculture (57%). Six complex types of weeds were formed in soybean crops, cereal-dicotyledonous-dicotyledonous-root-sprouting and dicotyledonous-grass-annual-grass-root-sprouting prevailed. For cultivation in crop rotation cereal annual species predominated, and dicotyledonous annuals predominated in monoculture. At the same time, the monoculture had a higher level of weeding than crop rotation, or it was equivalent. Conclusions. The species composition of weeds in soybean crops in fallow-crop-row rotation and monoculture differs significantly, which should be taken into account by the agronomic service of farms when developing methods of their control.