ALIEN PLANTS AS WEEDS IN AGROPHYTOCOENOSES IN THE SOUTH OF UKRAINE

Abstract

The paper presents the results of studies on the alien species as weeds in the fields of farm agrophytocoenoses on different soils. The studied farms are situated in Domanivskiy district of Mykolaiv region and Skadovsk district of Kherson region (Ukraine). Domanivsky district is located in the northwestern part of Mykolaiv region (Ukraine). Most of the area (south and west) lies within the Black Sea lowlands. The northern and eastern parts of the district where the experimental fields are located are spurs of the Podolian Upland. Skadovsky district is located in the south of Kherson region. It is a plain in the steppe zone of southern Ukraine. There were surveyed 8 fields with a total area of ​​260 ha. A floristic list, represented by 30 species of 28 genera, 10 families, 7 orders was compiled. The Asteraceae family (10 species, or 33.3%) occupies the first place in the family spectrum of the investigated agrophytocoenoses, which is characteristic for the most floras of the temperate part of the entire Holarctic. The Brassicaceae family with 8 species (26.6%) occupies the 2nd place. The Poaceae family has only 4 species (13.3%) and ranks third in the studied flora, which corresponds to the features of the zonal family spectra. The migration analysis showed the prevalence of ancient Mediterranean species in terms of the primary habitat type and archaeophytes in terms of their migration time. The studied species of alien plants should belong to the class StellarieteamediaeR.Tx., Lohmeyer & PreisinginR.Tx. exvonRochow 1951. The species of Ambrosia arthemisifolia, Amaranthus retroflexus, Echinochloa crusgalli, Iva xanthiifolia, Xanthium albinum (5 species) are  most common and malicious weeds for sunflower crops; Descurainia Sophia, Centaureacyanus, Papaver rhoeas, Raphanusraphanistrum. Sonchusarvensis, S. Oleraceus (6 species) are most common and malicious weeds for grains (barley); Conyza canadensis, Cenchrus longispinus, Portulaca oleracea, Tribulus terrestris Setaria viridis are 4 most common and malicious weeds for watermelon plantations.