Document Type : Research Paper

Authors

• Safoura Jafari ¹
• Mostafa Chorom ²
• Naeimeh Enayatizamir ³
• Hossein Motamedi ⁴

¹ Master of Science, Department of Soil Science, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Iran

² Associate Professor, Department of Soil Science, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Iran

³ Assistant Professor, Department of Soil Science, Faculty of Agriculture, Shahid Chamran university of Ahvaz, Iran

⁴ Assistant Professor, Department of Microbiology, Faculty of Sciences, Shahid Chamran University of Ahvaz, Iran

Abstract

Soil salinity induces a stressful environment for soil micro-organisms and reduces their number and activity. The objective of this research is investigating the effect of different levels of salinity on some of soil biological indicators and also assessing the effect of two types of halotolerant rhizospheric bacteria on the value of these indexes in soil. 35 strains were isolated from saline rhizospheric soils and their ability to grow in concentrations of 0 to 600 mM salt was evaluated. Among them, two isolates were identified as salt tolerant bacteria that were recognized as genera of Bacillus subtilis and Corynebacterium glutamicum. The factorial experiment, as the completely randomized design, was performed with two factors including salinity in four levels (2, 4, 8 and 12 dS/m) and bacteria in three levels (none inoculated, inoculated with Bacillus subtilis and inoculated with Corynebacterium glutamicum) in the greenhouse. The cultivated plant was barley. Different levels of salinity in soil were created by adding the mixture of salts including NaCl, CaCl₂ and MgCl₂. After 8 weeks, the amount of soil respiration, microbial biomass carbon and qCO₂ were measured in the soil. The results of the statistical analysis showed that the effect of salinity levels on these indicators were significant (P<0.001). Bacterial inoculation in different levels of salinity, significantly, increased the soil respiration (P<0.05) and microbial biomass carbon (P<0.001) and reduced qCO₂ (P<0.001) in soil. The results of this research showed that the halotolerant rhizospheric bacteria reduced the negative effects of salinity on soil microbial indicators.