Alleviation of salt stress in rapeseed (Brassica napus L.) plants by biochar-based rhizobacteria: new insights into the mechanisms regulating nutrient uptake, antioxidant activity, root growth and productivity

ABSTRACT

Amendment of saline soils with biochar and rhizobacteria is a new technique to diminish the negative impacts of salt stress on plants. Hence, an original pot experiment was conducted in a glass greenhouse at the University of Tabriz to investigate the performance of salt-stressed (0, 6 and 12 dS m⁻¹ NaCl) rapeseed (Brassica napus L.) plants in response to different biochar-related treatments (non-biochar, biochar, biochar-based Pseudomonas putida RS-198, biochar-based Azotobacter chroococcum RS-106 and both bacteria). The biochar-related treatments reduced sodium content, generation of reactive oxygen species, lipid peroxidation and enzymatic antioxidants in plant tissues while enhanced nutrient content, non-enzymatic antioxidants, main and lateral roots lengths and weights, main/lateral root length ratio, specific root length, root diameter, shoot length and weight, leaf area, chlorophyll content and seed and oil yields under saline conditions. The biochar-based Pseudomonas + Azotobacter was the superior treatment for reducing the harmful impacts of salt stress on rapeseed plants, which resulted in 83–109% and 69–115% improvements in seed and oil yields of this crop under moderate and high salinities, respectively. Therefore, inoculation of biochar with both rhizobacteria might be a novel approach for improving salt tolerance and productivity of rapeseed plants.

KEYWORDS:

• Azotobacter
• biochar
• root growth
• Pseudomonas
• salt tolerance

Acknowledgements

The support of this research project by the University of Tabriz is greatly appreciated.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/03650340.2022.2103547

Additional information

Funding

This work was supported by the University of Tabriz.