Alleviation of Salinity Stress on Some Growth Parameters of Wheat by Exopolysaccharide-Producing Bacteria

After isolation of halophilic bacteria from saline soils, the effects of two superior isolates producing exopolysaccharide TP7 and TP5 was investigated on some wheat growth parameters such as shoot and root dry weight and concentration of K+, Ca2+, Na+ and K+/Na+, Ca2+/Na+ ratios under saline stress. Inoculation with bacteria (TP7, TP5 and both of strains) had a positive effect on shoot weight (74.71, 57.52 and 82.45%) at EC 8 dS m(-1) and (45.26, 60.95 and 71.28%) at EC 16 dS m(-1). Also, TP7 and TP5 isolates can increase plant resistance to salt and drought stresses by decreasing Na+ uptake and in 16 dS m(-1) led to an increase in dry weight of root in comparison with control by 97.95, 128.29 and 193.53%, respectively. In higher-salinity treatments, all of treatments (TP5, TP7 and both of strains) had a significant effect on K+ concentration, especially in EC 16 dS m(-1) by 29.58, 45.94 and 53.56% and 35.50, 52.37 and 58.65% in water stress and non-water stress, respectively. The determination of 16S rRNA gene sequences of isolates TP7 and TP5 showed that they are mostly close to Bacillus subtilis susp. inaquosorum (98.49% sequence similarity) and Marinobacter lipolyticus SM19 (T) (97.69% sequence similarity), respectively. Generally, results showed that these isolates can be used as a tool for reducing adverse effects of salinity and drought stresses in wheat plant.