Evaluation of plant growth promotion chracteristics of native soil Azotobacter isolates from Golestan province

Over the past few decades, effort to increase production per unit area and excessive and unbalanced application of fertilizers has led to environmental destruction. Application of bio-fertilizers, without adverse impacts on environments and providing some plant nutritional requirements, has improved some physical, chemical and biological properties of soil. Azotobacter is one of the soil microorganisms which is able to simulate the growth of crops. This bacteria affects plant growth parameter directly or indirectly. This study was conducted for 43 strains of Azotobacter, and maximum molecular biological nitrogen fixation acetylene reduction (ARA) to isolate 3 times with 276 nmol h pipe, most can be little solubility of phosphorus in the medium Asprbr colorimetric method using spectrophotometer device to isolate No. 25 is equal to 232 mg l, Slightly soluble potassium minerals Aleksandrov's most potent medium of film photometer device to isolate No. 23 with 47 mg l, most potent hormone auxin in LB tryptophan medium with for colorimetric spectrophotometer method for isolate number 37 is equal to 98 mg l and More than half the diameter of the colony is a measure of the ability to produce siderophore on the CAS-Agar-related isolates 4, 9, 16, 18, 31, 37, 38, 40, 41 and 43 respectively. The ability to produce hydrogen cyanide was measured among all isolates, only 4 isolates were able to isolate the maximum amount of hydrogen cyanide is 43.