Influence of arbuscular mycorrhizae on plant growth, essential oil production and phosphorus uptake of Salvia officinalis L.

Arbuscular mycorrhiza fungi (AMF) contribute to the secondary metabolism and production of active ingredients in aromatic and medicinal plants. This symbiotic association is particularly affected by the availability of phosphorus (P) in the soil. This study was conducted on Salvia officinalis L. using two inocula, commercial Symbivit and Septoglomus viscosum (syn. Glomus viscosum), alone or supplemented with two doses of actual P (0.03, 0.06 g kg−1). The effects of these fungi and their combinations with P were determined in relation to the growth of sage plants (Regula variety), to the concentration of P in leaf tissues, and to the quantity and quality of essential oils (EOs). S. viscosum treated plants showed better growth with or without P-supply compared to non-mycorrhizal plants. The plants inoculated with S. viscosum presented the highest dry weight regardless of addition of P. Both AM fungi increased the leaf P content as more P was applied to the soil, whereas the EO content did not change with any of the treatments. Although the EO yield slightly increased with the Symbivit treatment, the chemical composition of the oil was drastically altered by S. viscosum in which the manool was the main component (28.13%), while α-thujone decreased (13.09%). These results suggest that AM symbiosis is a good candidate for promoting plant growth and essential oil composition and for improving P uptake in low fertility soils. Thus, mycorrhiza can be considered as a sustainable strategy based on natural resources in order to influence the manool and α-thujone content in sage EO composition. These compositions are very important to develop new classes of biocides and contribute to reducing risks to both human health and the environment.