Preliminary Study of Control and Biochemical Characteristics of Giant Hogweed (Heracleum sosnowskyi Manden.) Treated with Microwaves

There is an urgent need to develop new compensatory and human-safe methods for controlling invasive Heracleum species. This research aimed to determine the effectiveness of H. sosnowskyi control under microwave radiation and biochemical changes in tissues and sap after irradiation. In field experiments in southern Poland, the plants were cut and irradiated with a device generating electromagnetic waves (2.45 GHz, 32.8 kW/m2). The control efficacy of plants in the rosette phase irradiated for 5, 10, or 15 min was 20%, 100%, and 100%, respectively. The control efficacy of plants in the flowering phase irradiated for 7.5 or 15 min was 66% and 100%. The metabolomic analysis of tissues and sap of irradiated H. sosnowskyi showed significant changes, mainly in the content and composition of proteins and sugars. In tissues, the treatments resulted in protein denaturation and significant changes in the metabolism of amino acids and the glyoxylate and galactose pathways. The sap was rich in sugars, glutamic acid, glutamine, homoserine, serine, and methionine. More changes in metabolite levels were observed in the tissues irradiated for 7.5 min. In conclusion, microwave radiation of H. sosnowskyi for longer times, e.g., 10 and 15 min, efficiently controls it.