Quantitative comparison of ammonia and 3-indoleacetic acid production in halophilic, alkalophilic and haloalkalophilic bacterial isolates in soil

Isolation and identification of isolates with PGPR characteristic can be used to improve plant growth in saline areas. In order to quantitative measure of PGPR characteristic in native halophilic, alkalophilic and haloalkalophilic bacterial isolates of Khorasan Razavi soils, isolates were isolated and purified from six different areas to measure the concentration of ammonia production via corrected Nesslerization method and 3-indoleacetic acid as Salkowski method. The alkalophiles isolates showed maximum ammonia production (0.055%) among the three groups of bacteria which this amount was 9.5 times of its average in haloalkalophiles isolates (0.0058%) and 13 times of ammonia production average in halophiles (0.004%). Most of halophiles, alkalophiles and haloalkalophiles isolates were IAA producer with 0.0003, 0.0001 and 0.0021 percent respectively that the IAA amount in haloalkalophilic group was about 6 and 14.5 times of it in halophilic and alkalophilic isolates respectively. Equations to predict the concentration of ammonia and 3-indole acetic acid production was only significant in the haloalkalophilic isolates for ammonia production (P=0.046) and halophilic isolates for IAA production (P=0.015) under effect of electrical conductivity and pH in 0.05 probability level. Results represented that the multiple regression analysis for prediction of ammonia and IAA concentrations producing by isolates had not any significant performance in high and low concentrations under effect of electrical conductivity and pH. Uses of Nesslerization and Salkowski methods after some modifications show promises and are recommendable in research due to their ease of implementation and relatively accurate results.