Effect of Halophilic Exopolysaccharide-Producing Bacteria on Wheat Growth under Drought and Saline Stresses

Drought and salinity are the most important stresses which reduce crop production in arid and semiarid areas. Therefore, effect of halophilic exopolysaccharide-producing bacteria was investigated on decreasing drought and saline stresses. In the first step, the best isolates of halophilic exopolysaccharide-producing bacteria were selected from a saline soil in Eshtehard, Iran. Determination of 16S rRNA gene sequences of the isolates showed that TP7 and TP5 isolates were most closely related to Bacillus subtlis susp. Inaquosorum) T) (98.5% sequence similarity) and Marinobacter lipolyticus SM19(T) (97.7 % sequence similarity), respectively. Then, a study was carried out in factorial arrangement with completely randomized design on wheat. The factors included four bacteria treatments: without inoculation of bacteria (B1), isolated bacteria TP7 (B2), isolated bacteria TP5 (B3), and both isolates of bacteria (B4). Besides, four levels of soil salinity (2, 4, 8, and 16 dS m-1) and two soil moisture levels (75% and 25% of available water) were also part of the study. The results showed that the inoculated treatments had higher dry and fresh root and shoot weights, germination rate, and germination percent compared to non-inoculated treatment. This increase was remarkable in the treatments inoculated with both bacteria (B4) under the two moisture levels and at salinity levels of 8 and 16 dS m-1.