Effect of inoculation of two mycorrhizal fungi and two growth-promoting rhizobacteria on improvement of characteristics of Myrtus Communis L. seedlings under drought stress

The present study was carried out to investigate the effect of two mycorrhizal fungi and two growth-promoting rhizobacteria on survival and growth traits of Myrtus communis L. in water deficit conditions, as a completely randomized factorial design. Drought stress in three levels: 100% field capacity (without stress), 60% field capacity (mild stress) and 30% field capacity (severe stress) and biofertilizer in seven levels: control (without inoculation); inoculation with mycorrhizals of Funneliformis mosseae, Rhizophagus intraradices, and combination of these two fungi; inoculation with rhizobacterias of Pseudomonas fluorescens, P. putida, and combination of these two bacteria was considered in three replicates. Drought stress reduced and biofertilizers (in particular, composition of fungus, and combination of bacterias) increased the studied traits. In severe water deficit, combined treatments of fungal or bacterial improved height increment by 28-31%, leaf biomass by 51-52%, root biomass by 36-42%, total biomass by 37-41% and survival by 50% compared with the control (non-inoculation) ones. In severe drought stress, almost 50% of the seedlings survived without inoculation and 90-100% of them with inoculation, indicating the high tolerance of this species to drought. Due to the reduction of the destructive effect of water stress on M. communis seedling traits using biofertilizers, the use of these treatments, especially the combination of two fungi of Funneliformis mosseae and Rhizophagus intraradices or two rhizobacteria of Pseudomonas fluorescens and P. putida can be useful to improve seedling's growth characteristics.