Evaluation of Iron Content in Calcareous Soil Treated With Bacteria Producing Siderophore under Drought Stress

Despite the abundance of iron in the earth's crust and soil, this nutrient is not usually available for plants in calcareous soil with high pH. In the present study four superior isolates with alternative physiological traits (No. 3, 8, 20 and 23) isolated from 10 soil samples for producing siderophore and their contribution in solubilizing insoluble iron-containing compounds in calcareous soil were evaluated. Results showed that in spite of higher halo diameter to colony diameter of isolate No. 23 in CAS agar medium (3.46mm) at soil incubation test, DTPA-extractable iron using isolates No. 3 and 20 was greater than the ones in isolate No. 23 as 10.7 and 14.67 percent, respectively. Greatest amount of DTPA-extractable iron in the soil sample was obtained during 40-days incubation. Molecular test showed that isolate 20 was 99 percent similar to the strain Bacillus Sporothernodurans. Biochemical tests also revealed that isolate 8 probably belong to Entrobacteriaceae family and isolates 3 and 23 belong to Pseudomonas Genus.