Salt Tolerant Rhizobacteria Mitigating the Effects of Salinity Stress on Growth of Soybean (Glycine Max (L.) Merr.) on Salinity Soil

Abstract

Salinity is a serious abiotic stress that adversely affects plants. Soybean (Glycine max (L.) Merr.) is not a salt tolerant crop and salt stress is a major problem for its productivity. One way to mitigate salt stress is to inoculate with salt-tolerant growth-promoting rhizobacteria. The purpose of this study was to isolate local strains of salt-tolerant rhizobia and phosphate-solubilizing bacteria and to study their ability to promote soybean growth on saline soils. In our study, isolates of rhizobia and phosphatesolubilizing bacteria were isolated from the rhizosphere and nodules of soybean growing on saline soil. Their growth under salt stress conditions was studied and high salt-tolerant isolates were selected: three isolates of rhizobia and four phosphate-solubilizing bacteria. Under salt stress, isolates of rhizobacteria were studied for nodulation and phosphate solubilization, and active strains were selected. This strains were identified by the molecular genetic method of Sanger. It was found that rhizobia RH21, RH26, RH28 refers to Bradyrhizobium japonicum, phosphate solubilizing bacteria to Pseudomonas koreensis FT4, Bacillus pumilus FM12 and Bacillus sp. FC11. The inoculation with rhizobacteria mitigated of the salt stress was showed. This is demonstrated by an increase in indicators of growth of inoculated plants. The co-inoculation with two strains rhizobacteria (RH28 and FT4) most effectively mitigated salt stress: the roots weight was increased by 3 times, shoot by 2.7 times and number of nodules by more than 3 times compared with control without salinity. Our study showed that inoculation with local strains of salt-tolerant rhizobacteria increased resistance to salt stress, improved growth, and promoted ecological adaptation of soybeans to saline soils.