Physiological responses of common myrtle seedling (Myrtus communis L.) to multimicrobial inoculation under water deficit stress

Common myrtle (Myrtus communis L.) spread in arid and semi-arid regions of Iran which it has many uses in different ways.  In order to investigation of microbial inoculation influence on the physiological changes of M. communis seedlings under water deficit conditions a greenhouse experiment as a factorial in a completely randomized design with three replications was conducted.  Water deficit consisted of 30% field capacity (FC) (severe stress), 60% FC (mild stress) and 100% FC (without stress), and microbial inoculations were including of Funneliformis  mosseae, Rhizophagus intraradices, combination of these two fungal, Pseudomonas fluorescens, P. putida, combination of these two bacteria, and also control (without inoculation). According to the results, in each water regime the highest root colonization was observed in the combination of two fungal. This treatment promoted root colonization by 17.8, 11.3 and 7.75 times in 30% and 60% and 100% of FC treatments respectively compared to the control. Microbial inoculation improved plant yield efficiency in water deficit conditions. In severe water deficit treatment, combined treatments of fungal or bacterial increased photosynthesis (47-48%), stomatal conductance (39-41%), transpiration (62-65%), mesophyll conductance (57-64%), water potential (20-21%), and relative water content (1.4 times), and decreased intracellular CO2 concentration (28-31%) and electrolyte leakage (1.4 times) compared to the control. It can be suggested that microbial inoculation can encourage drought resistance of M. communis seedlings to water deficit.