Confrontation of soil symbionts and inhibition of oak (Quercus brantii) decay

The oak forests are one of the typical crucial ecosystems placed in western Iran. A remarkable area of these forests situated in Kermanshah province. Due to human manipulation, ecological and climate change are deteriorating. In this investigation, microbial isolation and treatments were offered to evaluate their effects on oak growth. Samples collected from Quercus brant ii of Kermanshah regions, Iran, and were cultivated on ISP۲ and NA medium, kept at ۲۸ °C for one month. The Microscopic identification and phosphate solubilization assay for primary and nitrogen fixation, hydrogen cyanide, protease, and phytohormone production performed. Lastly, Seedlings with selected isolate treated and growth and survival parameters measured.All strains were able to produce auxin and gibberellin in different values. All of the isolates able to solubilize phosphate. The outcomes of nitrogen fixation ability, protease, and siderophore production diverged among strains. Picked isolates exhibited hormone production properties as well as biocontrol influences according to tests. Co-treatment of Streptomyces sp. Qb۲- Pseudomonas sp. Qb, Streptomyces sp. Qb۲-Bacillus sp. Qb and Streptomyces sp. Qb۲- Pseudomonas sp. Qb had a notable effect on seedling growth parameters (P <۰ ·۰۰۱), oak species survival (P <۰ ·۰۰۱), and improved significantly the longitudinal growth,diameter, and dry weight percent of seedlings (P <۰ ·۰۰۵) Respectively. Streptomyces sp. Qb۲ and Bacillus sp. Qb strains had the highest and lowest inhibition effects on bacterial plant pathogen, Pseudomonas syringae. Streptomyces sp. Qb۲ strains significantly promote root formation. To our understanding, this is the first record of Streptomyces endophyte isolation from Iranian oak trees with biocontrol and growth-inducing impacts. It is also proposed to apply the co-treatment plan to increase biocontrol effects and growth induction.