Interaction between arbuscular mycorrhizae fungi inoculation (Glumus verciforme) and selenium nutrition on growth and biochemical indices of Moldavian balm (Dracocephalum moldavica L.) under drought stress condition

Drought stress causes reduction in growth and changes in biochemical indices of plants. In order to investigate the effect of arbuscular mycorrhizal fungi and selenium on reduction the detrimental effects of drought stress in Moldavian balm (Dracocephalum moldavica L.), a split plot-factorial experiment based on complete randomized block design with four replications was carried out under greenhouse condition. The main factor was three levels of drought [control, 0.75 Maximum Allowable Depletion (MAD) and 0.5 MAD] and sub factors included selenium at three levels (0, 100 μg per plant and 200 μg per plant) and inoculation with mycorrhizal fungi in two levels (non-inoculated as control and Glomus.verciforme). The results indicated that drought stress reduced height, dry weight and leaf area of plants. The lowest and highest value for all of these characteristics was obtained at 0.75 MAD and without drought stress, respectively. In non-stress condition, height, dry weight and leaf area of plants obtained from inoculation with mycorrhizal fungus and selenium were significantly higher than those of control. In all levels of drought stress, the content of catalase and peroxidase enzymes in plants inoculated with mycorrhizal fungus and selenium was significantly higher than that of control. The lowest content of catalase enzyme (25.06) was obtained in control and lowest content of peroxidase (14.81) was in the treatment with mycorrhizal fungus and selenium under 0.75 MAD drought stress. The highest content of catalase enzyme (53.62) was in inoculation with mycorrhizal fungus and 200μg selenium without stress, and the highest content of peroxidase (31.59) was obtained in 0.5 MAD stress and inoculation with mycorrhizal fungus and 200 μg selenium. Also, in condition of inoculation with fungus and selenium, the content of proline and MDA increased about 1 to 1.5 folds and about 1.3 to 1.5 folds, respectively, more than the control. Results showed that the presence of mycorrhiza and selenium in drought stress condition had a positive effect on growth and biochemical indices studied.