Effect of Arbuscular Mycorrhiza Inoculation on Nutrient Uptake and Essential Oil Composition of Dragonhead (Dracocphalum moldavica L.) under Drought Stress

To study essential oil components of Dracocephalum moldavica in response to mycorrhiza fungus inoculation under drought stress condition, a factorial experiment based on completely randomized design with three replications was carried out under greenhouse condition. The factors of the experiment were three levels of drought stresses [control, 0.75 maximum allowable depletion (MAD) and 0.5 MAD] and inoculation with mycorrhiza fungi in two levels (no mycorrhiza inoculation as control and Glomus verciforme inoculation). Essential oil components were recognized via gas chromatography (GC) and gas chromatography-mass spectrometric (GC/MS). The result showed that about 36 components in D. moldavica were identified through inoculation with mycorrhiza under drought stress. Concentration of 13 compounds of these were higher than the rest. Compositions of geranial (18.3%), geraniol (30.98%), geranyl acetate (26.78%) and neral (11.94%) had high quantities in essential oil. Drought stress and mycorrhiza inoculation increased the percentage of major essential oil components. The highest essential oil percentage (1.24%) was obtained by mycorrhiza inoculation treatment and drought stress at 0.75 MAD. Drought stress reduced the uptake of nitrogen, phosphorus and potassium elements, while mycorrhiza inoculation increased their uptake. The highest uptake of potassium was in non-stress and mycorrhiza inoculation conditions. It can be concluded that mycorrhiza inoculation under drought stress increased the uptake of nutrients and essential oil composition of dragonhead.