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

Abstract
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.