Investigating the effect of salinity stress and soil microorganisms on the absorption of mineral elements of Isabgol (Plantago ovata Forsk(.

Plantago ovata Forsk has a natural distribution in flora of Iran and its cultivation has economic importance. Salinity is one of the natural features of ecosystems in semi-arid and arid areas. In salinity stress, the high K+/Na+ ratio in plant tissues has been considered as one of the important physiological mechanisms in creating salinity tolerance in some plant species. Studies have shown that arbuscular mycorrhizal fungi and inorganic phosphate solubilizing bacteria increase the K+/Na+ ratio of the plant and prevent the negative effects of Na+ ion. These microorganisms play an important role in increasing the availability and absorption of essential elements and ultimately increasing plant production. In order to investigate the effect of salinity stress and microorganisms on the accumulation of mineral elements in Isabgol (Plantago ovata Forsk.) a factorial experiment based on randomized complete block with three replications was conducted in 2014 in research greenhouse of the University of Birjand. First factor was three levels of salinity 2.5, 5 and 10 dS.m-1. Second factor was arbuscular mycorrhizal fungi include four levels (None inoculated, Funneliformis mosseae, Rhizophagus intraradices and Glomus fasciculatum) and third factor was phosphate-solubilizing bacteria includes two levels (Pseudomonas fluorescens and No bacteria) which was prepared in soil biology lab of university of Tehran. At the stage of physiological maturity, the plants were removed from the pot and dried. The dry weight of each sample was then measured. In order to measure the elements for drying and combining with chloridric acid, the concentrations of mineral elements in the plant were measured. The results showed that salinity increased the absorption of phosphorus, nitrogen and potassium, increased sodium absorption and sodium / potassium ratio, and reduced the dry weight of the stem. Application of soil microorganisms under salinity stress conditions, in addition to increasing the absorption of essential nutrients, reduced the sodium ion absorption and sodium / potassium ratio and increased stem dry weight. Results showed that the highest percentage of phosphorus was 7.21% in the 2.5 dS.m-1 + Rhizophagus intraradices + Pseudomonas fluorescens. The highest nitrogen content was 2.28% in the 2.5 dS.m-1 + Arbuscular mycorrhiza (Rhizophagus intraradices). The highest potassium content was 48.7 mg/g dry weight in the 2.5 dS.m-1 salinity + Funneliformis mosseae arbuscular mycorrhizal fungus. The lowest sodium and sodium / potassium ion in the stem were 3.1 mg/g dry weight and 0.06 mg/g dry weight in the treatment composition of 2.5 dS.m-1 and the application of arbuscular mycorrhiza Rhizophagus intraradices were obtained. Also, the highest dry weight of stems was obtained in the treatment composition of 2.5 dS.m-1 + Rhizophagus intraradices + no bacteria intake of 3.9 grams. Although, this difference was not statistically significant with the combination of treatments in which the Pseudomonas fluorescens solubilizing bacterium was used. Overall, the results showed that the application of soil microorganisms could compensate for the negative effects of salinity stress by increasing the absorption of essential elements and reducing the absorption of sodium element. Simultaneous use of Pseudomonas fluorescens and Rhizophagus intraradices can best reflect the absorption of elements under salt stress conditions and increase the production of Isabgol. Keywords: Arbuscular mycorrhizal fungi, Phosphate-solubilizing bacteria, Macro elements, Haloculture.