Integrative application of cyanobacteria and antioxidants improves common bean performance under saline conditions

Cyanobacteria (CB), known as blue-green algae, are useful microscopic organisms that can lead to improve the nutrient uptake, plant growth, and plant tolerance to abiotic stress such as salinity. The impacts of CB, with or without glutathione (GSH) and ascorbic acid (AsA) and their combinations on morphological, physiological, metabolic, and enzymatic activity status in common bean plant grown on salt stressed soil were investigated. All single (CB, AsA or GSH), or combined (CB + AsA, CB + GSH, CB + AsA + GSH or CB + GSH + AsA) applications significantly increased plant length, number and area of leaves, plant fresh and dry weights, yield parameters (green pods weight per plant, dry seed weight per plant and 100-seed weight) and leaf photosynthetic pigments and their photochemical efficiency (Fv/Fm and PI) of common bean plants compared to the control in 2015 and 2016 growing seasons. In addition, relative water content, membrane stability index, contents of soluble sugar, proline, AsA, GSH, N, P and K+ ion contents, and activities of superoxide dismutase, catalase and guaiacol peroxidase were significantly increased with all of the mentioned applications. In contrast, electrolyte leakage and Na+ ion content was significantly decreased. The best response was obtained with the integrative CB + AsA + GSH and CB + GSH + AsA treatments, with distinguish of the former. Overall, these results suggest that supporting the seed CB application with foliar application of AsA and GSH helped to increase the defense systems of the common bean plant to tolerate the adverse effects of soil salinity.