Effects of endophytic fungus Piriformospora indica on growth and essential oil content of Pimpinella anisum plant under water deficit conditions

The products from medicinal plants are directly used for human consumption or used in the formulation of drugs. Therefore, in addition to quantity, their quality is also considered. Water deficit stresses could affect the quality and quantity of the active substance in these plants. It has been reported that the use of Piriformospora indica as an endophytic fungus in some plants reduces the harmful effects of water deficit stress. Probably this fungus will have direct and indirect roles in the production of plant metabolites likely by reducing the adverse effects of water deficit stress. Accordingly, this research was conducted in a completely randomized design with factorial arrangement with two factors including two levels of P. indica (inoculated and non-inoculated) and soil moisture with three levels of 80-90 %FC (W0, 60-70 %FC (W1) and 40-50 %FC (W2) with four replications. The results showed that inoculation with P. indica increased the measured characteristics of anise compared to the non-fungal treatment. Severe water stress (W2) lead to an increase in shoot dry weight (58.93%), root dry weight (56.25%), seed yield (392.06%), essential oil yield (340.08%), percentage of essential oil (154.55%) and the amount of anethole essential oil (236.85%) in inoculated compared to the non-inoculated plants. In fungal treatment, the essential oil yield and percentage and the amount of anethole had the highest value at the level of moderate stress (W1). In this study, it was found that P. indica increases the medicinal quality of anise essential oil by increasing its anethole amount.