Effect of Arbuscular Mycorrhizal Fungus, Plant Growth Promoting Rhizobacterium, and Drought Stress on Different Forms of Soil Potassium and Potassium Uptake of Maize

A set of greenhouse experiments in a factorial completely randomized design was conducted to evaluate the effects of arbuscular mycorrhizal fungus (Glomus intraradices), Pseudomonas fluorescence bacteria, and drought stress on potassium absorption by maize (Zea mays) and also on different forms of potassium in a calcareous soil. The factors were consisted of arbuscular mycorrhizal (AM) fungus at two levels: G0 (not inoculated with fungus) and G1 (inoculated with Glomus intraradices), bacteria at two levels: B0 (not inoculated with bacterium) and B1 (inoculated with Pseudomonas fluorescence) and drought stress at four levels: S0 (without stress), S1 (%75 FC), S2 (%50 FC) and S3 (%25 FC). As drought stress increased, the concentration of potassium different forms and uptake increased, and root colonization percent decreased. Co-application of mycorrhizal fungus and bacterium significantly increased root colonization percent. With increasing of drought stress levels, singly using of fungus and co-application of mycorrhizal fungus and bacterium in comparison with non inoculated treatments increased the concentration of potassium different forms and uptake.