Responces of Lemna minor L. to the exogenous phenolic compounds action

The study tested the morphological and physiological reactions of floating macrophyte Lemna minor L. under the exogenous phenolic compounds action. Plants were grown for 20 days in model systems under natural light at room temperature. Hydroquinone and resorcinol (1 and 10 mg L-1) were added in experimental vessels with water. Control plants were incubated in water without the addition of pollutants. Responses of L. minor to phenols action were studied by evaluating the degree of fronds depigmentation (in dynamics) and measuring the projected area of the epidermis and mesophyll cells and chloroplasts (after incubation). The degree of depigmentation of L. minor fronds depended on the type of pollutant and its concentration and exposure time. Hydroquinone caused a significant degree of fronds damage compared to the control plants and to plants under effect of resorcinol. Mesophyll cells of L. minor incubated with resorcinol were smaller in comparison with the control ones. Hydroquinone did not have significant impact on the projected area of the mesophyll cell. The size of epidermal cells in the presence of resorcinol (10 mg L-1) decreased compared to the control ones, but their number increased (compared with the hydroquinone). In the presence of hydroquinone (1 and 10 mg L-1) epidermal cell size increased (on average 20 % compared to control). The chloroplasts projection area decreased under the hydroquinone and resorcinol action, and to the greatest extent - at a concentration of 10 mg L-1. The research results lead to the conclusion about the possibility of using L. minor as a test-object for the bioassay of wastewater polluted by phenolic compounds.