S25 - Session O4 - Essential oil content and physiological response of Mentha genotypes under different UV-treatments

Authors: Charlotte Hubert *, Guido Steyns, Thorsten Kraska, Katharina Luhmer, Marcel Dieter Moll, Ralf Pude

Mentha sp. are widely used as feedstock for essential oil production and components in multiple products of the food industry. Healthy and vital plants with high amounts of essential oils are prerequisite for maximizing yield. The present study focused on plant vitality, biomass and essential oil content under different UV scenarios. For this, three different Mentha genotypes ( Mentha x piperita 'Polymentha', Mentha x piperita 'Fränkische Blaue' and Mentha suaveolens 'Apfelminze') were exposed to different levels of UV radiation (natural UV, UV-B-increased and shaded regimes). UV-B radiation was increased to 1,500 W/m² UVB (157% of control) and shaded by 62% in relation to the control. Besides UV-B, shading reduced PAR by 62% as well. Non-invasive phenotyping provided information on plant vitality using hyperspectral vegetation indices (VIs). Plant vitality was significantly influenced by light regime. Additionally, genotypes were distinguishable via VIs under same UV-conditions. Apart from that plant vitality, fresh biomass varied significantly for the three genotypes under identical light conditions. 'Apfelminze' and 'Fränkische Blaue' did not show treatment related differences in dry matter, while 'Polymentha' yielded significantly higher dry matter under control conditions, followed by the shaded scenario followed by UV-increased conditions. Oil yield and composition are in the process of analysis. In conclusion the results reveal that the three Mentha genotypes react differently in regard to biomass accumulation and overall stress under UV-B exposure and UV-B and PAR reduction. In the face of higher irradiation due to climate change, a targeted selection of genotypes seems promising to ensure high yields from Mentha .