Evaluation of abundance and functional diversity of endorhizobacteria isolated from pistachio seedlings in management soils with different characteristics

A greenhouse study was conducted to compare the abundance and functional diversity of endorhizobacteria of pistachio seedlings grown in three soils with different chemical and physical characteristics. After two months, the abundance of endorhizobacteria and some important plant growth promoting-properties including Indole Acetic Acid (IAA) production, nitrogen fixation and ACC utilization as the sole source of nitrogen were determined. The results showed that the abundance of endorhizobacteria was the highest in soil 2, which contained the highest organic carbon content. Also, the abundance of endorhizobacteria isolated from soil 1, 2 and 3 were 48.5, 60 and 53 % for IAA production; 27.3, 62.9 and 50 % for nitrogen fixation; and 15.2, 48.6 and 16.7 % for ACC utilization, respectively. Based on high organic carbon content, high abundance of endorhizobacteria in soil 2 and their high capability in production of plant growth promoting compounds, it seems that there is a relationship between soil organic carbon and endorhizobacteria population and also the abundance of these bacteria.