ALLELOPATHIC EFFECT OF INVASIVE SPECIES GIANT GOLDENROD (SOLIDAGO GIGANTEA AIT.) ON CROPS AND WEEDS

The aim of the study was to determine allelopathic potential of invasive species giant goldenrod (Solidago gigantea Ait.) on germination and initial growth crops (carrot, barley, coriander) and weed species velvetleaf (Abutilon theophrasti Med.) and redroot pigweed (Amaranthus retroflexus L.). Experiments were conducted under laboratory conditions to determine effect of water extracts in petri dish bioassay and in pots with soil. Water extracts from dry aboveground biomass of S. gigantea in concentrations of 1, 5 and 10% were investigated. In petri dish bioassay, all extract concentrations showed allelopathic effect on germination and seedling growth of crops with reduction over 25 and 60%, respectively. Both weed species germination and growth were greatly suppressed with extract application. In pot experiment, allelopathic effect was less pronounced. Reduction in emergence percent, shoot length and fresh weight of carrot were observed. Barley root length and fresh weight were reduced with the highest extract concentration. No significant effect on seedling emergence and growth of A. theophrasti was recorded, while emergence of A. retroflexus was inhibited for 14.4%. Germination and growth of test species decreased proportionately as concentration of weed biomass in water extracts increased. Differences in sensitivity among species were recorded, with A. retroflexus being the most susceptible to extracts.