The phytopathogenic fungus Botrytis cinerea causes grey mould on numerous economically important plants. We investigated the antifungal activity of the essential oil (EO) of caraway (Carum carvi) and its main compounds, carvone and limonene, on the growth of the fungus B. cinerea and the response of lettuce to different EO concentrations. We determined the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) in liquid Sabouraud Broth medium, monitored mycelial growth on solid Gelose Sabouraud 2 (SAB2-D) medium, spore germination and sclerotia formation. We evaluated the effects of EO on lettuce by assessing visual changes and mean fresh mass. In the first experiment, fungal growth was observed in the control (0 µL/mL) and at a concentration of 0,05 µL/mL, but not at 0,25 µL/mL; MIC and MFC were therefore 0,25 µL/mL. In the repeated experiment, growth was recorded at concentrations from 0 to 0,25 µL/mL; MIC was 0,50 µL/mL, while MFC was not determined. The highest mean inhibition of mycelial growth was recorded with carvone and its combination with limonene, while the values for limonene were negative. The highest mean number of spores was found with EO, carvone and the combination of carvone and limonene, and the lowest with limonene. One-way analysis of variance and Tukey's test confirmed statistically significant differences (p < 0,05). Sclerotia differed among treatments in predominant colour and type, and differed statistically significant in number. On lettuce, we observed changes in leaf colour, leaf margin necrosis, curling, wrinkling and finally leaf drying. Since changes also occurred in the control, we cannot attribute all of them to the effects of EO. The lowest mean fresh mass was found in the control and the highest with EO at a concentration of 2,00 µL/mL; the difference was statistically significant (p < 0,05).
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