Application of halotolerant Azotobacter chroococcum W4ii isolated from technosoils to mitigate salt stress in wheat plant

Technosoils are soils affected by human activities. One such soil is present in Inowrocław, central Poland, influenced by soda lime repository. Azotobacter chroococcum W4ii was isolated from the rhizosphere of wheat (Triticum aestivum L.) grown in the technosoils and checked for its plant growth properties on wheat plants under salt stress. Wheat seeds co-inoculated with A. chroococcum W4ii under 200 mM salt stress showed significant improvement in various growth parameters such as plant height, shoot biomass, chlorophyll b content compared to un-inoculated ones. Bacterial inoculation decreased the level of malondialdehyde (MDA) whereas elevated the antioxidative enzymatic activities of peroxidase (POD). The test isolate also enhanced the level of defense enzymes like β-1, 3 glucanase, which can protect plants from the infection of pathogens. The bacterium could also successfully colonize the wheat plants. These results indicate that A. chroococcum isolated from the technosoil has potential to promote the wheat growth under salt stress and can be further used as bioinoculant in the salt affected agricultural fields.