Tolerance of adventive macrophyte Lemna gibba L. to copper ions: range evaluation

In recent decades, adventitization processes in flora have become more vigorous, which poses a threat to biodiversity. Adventive plant species occupy new territories, including transformed ones, and oust native species. In this regard, it is relevant to study the tolerance range of alien species to high technogenic loads since it can help assess the spread of adventive plants. The aim of the research was to study the response of the adventive macrophyte Lemna gibba L. to the copper ions action in a gradient from 0 to 10 mg/L. Duckweed fronds were incubated in model systems for six days under natural light conditions. A high positive correlation between copper content in the nutrient solution and plants was revealed. Moreover, the rise of metal accumulation was exponential. With an increase in copper concentration ≥ 0.5 mg/L, its phytotoxic effect manifested itself through the increased prooxidant content and the depigmentation of fronds due to the photosynthetic pigments degradation. At the maximum copper concentration (10 mg/L), the chlorophyll content was 2.5 times lower, and carotenoids, 11.5 times, as compared to the control sample. The study assessed L. gibba tolerance range to the copper ions action and identified physiological and biochemical parameters that can serve as toxicity biomarkers.