Isolation and Identification of Azotobacter from Some Plants Grow in Gypsiferous Soil and Evaluation of Its Efficiency for Nitrogen Fixation and Production Indole (IAA) and Solubilizing Phosphate

Abstract

Twenty samples of Gypsiferous soil where collected from different sites of Salahuddin province (Tikrit University, Alam and Samarra) from Rhizosphere of different plants roots (wheat, barley, corn, peas, lettuce, , cabbage , cauliflower , turnip , onions, chard, radishes, Cresson, celery, malve, tomato, watercress, chickpeas, cucumbers) , to isolate and identify of Azotobacter Bacteria from these samples , and test the efficiency of these isolates in nitrogen fixation and production of auxin (indole acetic acid IAA) and phosphate. The results showed that the highest nitrogen fixation and production indole Acid Acetic (IAA) and phosphate solubilizing recorded in A.chroococcum, followed by A.vinelandii, then A.beijerinckii, and the (Az2) isolate which belong to A.chroococcum gave the highest value, this isolate gave 6.70 mg.L-1, 28.6 µg.ml-1, and 192 of fixed nitrogen , indole production and phosphate solubilizing respectively , while the efficient isolate of A.vinelandii (Az12) gave 5.12 mg.L-1 ,23.0 µg.ml-1and 186 respectively, and the only isolate of A.beijerinckii gave 3.91 mg.l -1 ,17.4 µg. ml -1 and 177 respectively.