Arbuscular mycorrhizal fungi colonize the roots of most vascular plants. In a symbiotic relationship they enable them to obtain nutrients and water from the soil. They play an important ecosystem role, so their preservation in soil is essential. Soil microorganisms are very sensitive to agricultural practices. In grassland, symbiosis is negatively affected by intensive practices such as sowing monoculture crops, overgrazing, overmowing and overfertilization. In the thesis, we focused on the impact of fertilization and mowing on the occurrence and intensity of arbuscular mycorrhiza in moist semi-natural grassland. The impact of both factors was studied at the Department of Agronomy, Biotechnical Faculty, University of Ljubljana, in the long term Travistor experiment. In our research, we collected a total of 120 samples of soil cores with roots from mid-May to mid-June 2023, 3 samples from each of 4 replicates per treatment. In ten treatments, 2-cut regime, which includes two mowings and imitation of autumn grazing or 4-cut regime was combined with different doses of mineral fertilizers and/or slurry. Roots were extracted from the samples, cleaned and stained for chitin after transillumination. Presence of arbuscular mycorrhiza and presence of arbuscules were assessed under a microscope. Characteristic structures of arbuscular mycorrhizal fungi were observed in all samples. We found out that the treatments that were mowed twice had statistically significant higher mycorrhizal intensity and a higher mycorrhizal intensity in the colonized parts of the roots compared to the treatments that were mowed four times. Results did not show a statistically significant effect of fertilization regimes on studied parameters.
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