Received January 27, 2023
Rare earth elements (REEs) can harmfully affect the growth and development of several plant species. However, there is a lack of studies providing the effect of REEs on Limbarda crithmoides seedlings. In the present study, the growth parameters, chlorophyll content, macroelement uptake, phenolic compounds and flavonoid contents of the halophyte L. crithmoides were analysed, after 14 days of exposure to increasing concentrations (up to 10 µM) of two light REEs; lanthanum (La) and cerium (Ce), to assess the phytotoxicity level of these REEs in the chosen species. La and Ce contents in the plant tissues were determined as well. Results revealed an inhibitory effect of La and Ce on plant growth; the length and the dry biomass production of the shoots and roots significantly decreased in all REEs concentrations, when compared to the control. Similar trend was recorded in chlorophyll a and b contents in plant leaves. Moreover, La and Ce treatments significantly decreased the uptake of potassium, calcium and magnesium in the shoots and roots of L. crithmoides while the amounts of both La and Ce were found elevated in the same organs. All La and Ce treatments promoted the stimulation of phenolic compound biosynthesis in shoots and roots. According to our experiments, the halophyte L. crithmoides was very sensitive to both La and Ce toxicity.
Key words: Light REEs, Limbarda crithmoides, growth inhibition, phenolic compounds, macronutrient uptake