Low and Moderate Rice-Sodic Soils Affect Bacterial Diversity and Their Functions

Sodicity is a significant abiotic stress that impairs plant growth and crop production. Understanding their properties is critical to establishing sustainability in sodic soil, and microbial diversities play a significant role in maintaining soil properties. Thus, this study uses a high throughput metagenomic approach to explore the impact of two different sodicity gradients on bacterial diversity and metabolic functions in the rice rhizosphere. The rice rhizosphere soils were collected from low sodic (L2- Trichy) and moderate sodic (L4- Chinna Salem) regions in Tamil Nadu, India, and Illumina sequencing was performed by targeting V3–V4 regions of 16S rDNA. The functional information related to bacteria was determined using KEGG and CAZyme analysis. The results revealed that the soil properties viz., pH, exchangeable sodium percentage (ESP), and organic carbon (OC), were found to be significant driving forces in influencing bacterial communities. The most common phyla found in sodic soils were Proteobacteria , Bacteroidetes , Chloroflexi , Acidobacteria , Firmicutes , Verrucomicrobia , Chlorobi , Actinobacteria , Gemmatimonadetes , and Planctomycetes . The abundance of Firmicutes , Actinobacteria , Acidobacteria , and Chloroflexi was particularly noticeable. However, Proteobacteria decreased with increasing sodicity. The KEGG analysis revealed that the carbohydrate, amino acid, and energy metabolism were reduced in moderate sodicity. In contrast, lipid metabolism was the primary metabolism of bacterial communities localized in both the sodic environments. Overall, our results showed that the soil properties of the sodic soil are the primary factor determining bacterial diversity and its functions.