The Effect of Arbuscular Mycorrhizal Fungi on Plant Development and Accumulation of Phenolics in the Flower Heads of Meadow Arnica (Arnica chamissonis Less.)

Meadow arnica is a valuable medicinal plant, used in both the pharmaceutical and cosmetic industries. The aim of the study was to determine the influence of arbuscular mycorrhizal fungi (AMF) on the development, yield, and quality of flower heads (raw material) of meadow arnica grown in an organic farming system. The inoculation of plants with AMF improved the mass of above- and underground organs, including the mass of raw material, as well as the content of chlorophylls and general sugar in the leaves, followed by enhanced starch storage in the roots. The content of phenolics in the raw material was determined using high-performance liquid chromatography (HPLC). The following flavonoids were assessed here: cynaroside, rutin, hyperoside, cosmosiin, astragalin, and diosmetin, as well as the phenolic acids: neochlorogenic, chlorogenic, caffeic, ferulic, rosmarinic, cichoric, 3,4-di-O-caffeoylquinic, and 1,5-dicaffeoylquinic acids. The contents of these substances were higher in non-inoculated plants than in inoculated ones, which contradicts most studies conducted to date on medicinal and aromatic plants. Nevertheless, the results are interesting primarily because of the beneficial developmental changes in inoculated plants, as evidenced by a significantly higher mass of arnica flower heads, more efficient uptake of mineral nutrients from the soil, and lower nitrogen levels in aboveground organs.