Role of Arbuscular Mycorrhizal Fungi on the photosynthetic pigments of Medicinal Plant Lavandula officinalis

Drought stress is one of the most serious world environmental that threats the crop production, might be compensated by symbiotic soil microorganisms. The present investigation was undertaken to evaluate the physiological responses of the Lavender plants to inoculation with arbuscular mycorrhizal fungi (Funnelliformis mosseae, Rhizophagus irregularis compared with non-inoculated control treatment) under different irrigation levels (irrigation at 75% FC, 50% FC and rainfed as well-watered, moderate stressed and severe stressed conditions, respectively). The 2-yeares (2015-2016) factorial experiment was conducted based on a randomized complete block design with three replications at Urmia University (latitude 37˚33 09 N, 45˚05 53 E and 1362 m above sea level). Severe stress decreased chlorophyll a (from 0.25 to 0.10 mg/g FW), chlorophyll b (from 0.29 to 0.10 mg/g FW) and total chlorophyll (from 0.54 to 0.20 mg/g FW) in the non-inoculated plants as compared to well-watered plants, but those positively impressed in plants inoculated with mycorrhiza, especially “F. mosseae” species. AMF inoculation caused a 3-fold increase in total chlorophyll as compared to non-inoculated control plants. Mycorrhization with “F. mosseae” and “R. irregularis” was the most effective under rainfed and moderate stress conditions, respectively.