Drought is one of the most critical environmental stressors affecting agricultural productivity around the world and it considerably results in yield. Symbiosis interaction between plants and soil microorganisms are considered to enhance plant tolerance in a/biotic conditions. In this study, the impact of Glomus mosseae, Pseudomonas fluorescens strain 169 and both of them under imposed water stress (flowering and pod filling stages) of mung bean (Vigna radiata (L.) Wilczek) was evaluated in two farm experiments during 2016 and 2017. Eco-physiological parameters have been recorded which showed that drought stress reduced the number of leaves, root colonization and seeds yield of mung bean. Mixed inoculation of G.mosseae and P.fluorescens 169 was more effective in alleviation the harm effects of drought stress. Enzymes assay suggested that co-inoculation of G.mosseae and P.fluorescens 169 was more effective to increase antioxidative defense system like catalase (CAT), glutathione peroxidase (GPX) and glutathione reductase (GR) activities. H2O2 contents were increased by water stress both in cutting irrigation at flowering and pod filling stages. In conclusion, plants inoculated with combination of G.mosseae and P.fluorescens 169 had less oxidative damage over control plants.

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Two years experiment were conducted in 2016-2017 as split-plot based on randomized completely block design with three replications to morpho-physiological responses of Lemon Balm (Melissa officinalis L.) plant to mycorrhizal fungi species treatments (control, Rhizophagus intraradices, Funneliformis mosseae, Glomus hoi and combined application of all three species) under different irrigation regimes (irrigation after 70, 100, 130 and 160 mm evaporation). In results, the highest oil yield was achieved in irrigation at 100mm+application of all three species of mycorrhizal fungi. Irrigation after 100 mm evaporation increased this trait by 33% compared to irrigation after 70 mm evaporation due to increase in essential oil percentage under dehydration conditions, however, increasing drought stress led to a significant decrease in essential oil yield. In terms of physiological parameters, dehydration led to an increase in proline content and antioxidant activates. In general and according to the results, modifying the destructive effects of water deficit stress and the use of mycorrhiza can increase the essential oil of lemon Balm. But aggravating water deficiency conditions can drastically reduce the essential oil yield. The founds could be helpful for herbal medicine researchers to achieve high-quality drugs.