Phytotoxic and microbiological activities of soil-applied microencapsulated peppermint (Mentha x piperita L.) essential oil

During this fellowship I performed several greenhouse and laboratory experiments, aiming at assessing the phytotoxic and microbiological effects of microencapsulated peppermint (Mentha x piperita L.) essential oil (MPO). The different doses of MPO were applied in the pot experiments either into vermiculite or top layer of arable soils. As the acceptor-species, I used four maize cultivars, one cultivar of mustard and a weed– lambsquarters (Chenopodium album L.). The microbiological analyses were performed using i) commercial strain of arbuscular fungus Rhizophagus irregularis on maize roots by intersection method, and ii) natural soil-microbiota by FDA biotest. I have found, based on the ED50 analysis, that the phytotoxic effect of MPO is both dose and species as well as soil-medium dependent. The biochemical analyses revealed, that the plants’ response to the application of MPO is typical for the allelopathic stress. The microbiological responses to the MPO applications were not clear enough to conclude and should be continued further.