LAUSR

ABSTRACT Mycorrhizal symbiosis may help plants to compensate the water deficit-induced macronutrients, secondary metabolites and osmotic adjustments as the basis of crop production. The present investigation was undertaken to evaluate the physiological responses of the lavender (Lavandula officinalis L.), rosemary (Rosmarinus officinalis L.) and thyme (Thymus vulgaris) host plants to inoculation with mycorrhizal fungi (Funnelliformis mosseae, Rhizophagus irregularis compared with non-inoculated control treatment) in different irrigation levels (irrigation at 75% field capacity, 50% field capacity and rainfed). The 2-year (2015–2016) factorial experiment was conducted based on a randomized complete block design with three replications at Urmia University. The results showed that the stress treatments promoted the generation of osmotic adjustment (total soluble sugars and proline) in non-inoculated plants more than plants inoculated with fungi species. Nutrient (nitrogen, phosphorous and potassium) concentrations and leaf chlorophyll, reduced by water-limiting irrigation, were enhanced with mycorrhizal inoculation. Colonized plants were better adapted and had greater relative water content under stressful conditions due to higher absorption sites for water and nutrients. Also, stress treatments stimulated the phenylalanine ammonia-lyase, DPPH radical-scavenging activity and, the total phenolic and flavonoids content in non-inoculated plants more than that inoculated with two fungi species.