Effects of using arbuscular mycorrhizal fungi to alleviate drought stress on the physiological traits and essential oil yield of fennel

This experiment was conducted to evaluate the physiological traits and essential oil yield of fennel affected by mycorrhizal fungal under different irrigation regimes. Field experiments were conducted at the Faculty of Agriculture, Yasouj University, Iran during the 2011 and 2012 years. The experiments were conducted using a randomized complete-block design with a split plot arrangement of treatments through four replications. The first factor included four irrigation regimes as main plot, and the second factor included three mycorrhizal fungus treatments as sub plot. The results indicated that irrespective of the mycorrhizal species and the drought stress intensity, inoculated fennels showed more essential oil yield, leaf and grain nutrient content and osmotic adjustment than did non-inoculated fennels. The positive effect of mycorrhizal symbiosis on leaf nutrient content and osmotic adjustment parameters was higher with high intensity of drought stress than with low intensity of drought stress. Results indicate that different AM fungi species even within the same genus have different effects on medicinal plant response to drought stress. The application of these microorganisms could be critical in the cultivation of medicinal plants under arid and semi-arid conditions, where water is the most important factor in determining plant growth and yield.