Streptomyces griseoincarnatus strain RB7AG promotes Oryza sativa (var. swarna) growth under salt stress: mechanisms and potential applications

Abstract

Abstract The plant growth promoters (PGP) are the natural fertilizers that enhance the overall growth of the plant. We defined Streptomyces strain RB7AG as a potential halotolerant growth promoter and assessed its impact on rice plants' performance under salt stress. The organism was able to thrive at concentrations up to 10% of NaCl (w/v), optimal at 6% as measured by their cell growth, viability, and secondary metabolite production. Under salt stress, isolates were viable and generated Indolic chemicals and siderophores. The bacterized plants found to accumulate higher level of proline and antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), and catalases (CAT) that are subjected to salt stress, particularly those treated with Streptomyces strain RB7AG, which helps the plants to thrive in the adverse condition. The Streptomyces-treated plants were also found to have increased roots and shoots length, implying a systemic tolerance mechanism. The strain’s formulations were created utilizing five organic and inorganic wastes as the carrier medium, and the shelf life of the propagules was also tracked. Vermicompost and vermiculite formulations were found to have the highest viable bacteria after 3 months of storage period.