Arbuscular Mycorrhizal Fungi (AMF) Influence Yield and Essential Oil Content and Composition of Sage (Salvia officinalis L.) Under Different Water Regimes

Essential oil-bearing plants are valued for their aromatic qualities and medicinal value. An example of such a plant is sage (Salvia officinalis L.), one of the most important aromatic herbal plants. Rich in essential oil (EO), sage herb is used in pharmaceutical and cosmetic production and as a spice. This study was conducted to determine the effect of arbuscular mycorrhizal fungi (AMF) on the morphological characteristics, yield, and EO production of sage under different irrigated conditions: 95 ± 5, 75 ± 5, 50 ± 5, and 25 ± 5% field capacity (FC). Maximum herb dry biomass yield and leaf dry biomass yield were obtained at the 95, 75% FC irrigation level, and the highest leaf EO (1.361%) was at 75% FC. The high yield of herb and leaf dry biomass, as well as the highest EO in herb and leaves, was observed with AMF. A group of monoterpenes and sesquiterpenes dominated the EO. The main compounds were 1,8-cineole, α-thujone, β-thujone, camphor, E-caryophyllene, and viridiflorol. The chemical composition of EO has changed under irrigation. Under severe stress (25% FC) and moderate soil moisture (50% FC), the proportion of monoterpene hydrocarbons and oxidized sesquiterpenes was higher than at 75% and 95% FC. The proportion of camphor, α-thujone, and β-thujone was higher with AMF only under severe water stress. With increasing soil moisture, the proportion of α-thujone and β-thujone in EO decreased. A positive correlation was found between EO content and the number of leaves per plant. Our results indicate the prospects for practical application of AMF in combination with the irrigation of sage plants.