Interactive Effect of Rhizobium Inoculation, Sodium Benzoate and Salinity on Performance and Oxidative Stress in Two Fababean Varieties

A pot trial was designed to investigate the impact of Rhizobium inoculation and/or sodium benzoate application on performance of two contrasting fababean varieties i.e., Giza Blanka (salt tolerant) and Giza 634 (salt sensitive) grown in sandy soil under two levels of salinity (3000 and 6000 ppm). High salinity (6000 ppm) greatly reduced nodules formation in both varieties. Rhizobium inoculation reduced the inhibitory effect of salinity and plants were able to survive better. Giza Blanka, surpassed the other variety in all characteristics. Leaf area, Ka:Na ratio, protein content, malondialdehyde and superoxide dismutase activity were greatly affected by increasing salinity in both varieties. Hydroxyl scavenger, (sodium benzoate) positively improved leaf area reduced transpiration rate, malondialdehyde content (MDA) in plant leaves and showed a slight increase in the activity of enzyme superoxide dismutase (SOD). Rhizobium inoculation increased plant leaf area, reduced MDA content in plant leaves and did not show a significant effect on SOD activity in plant roots, but the interaction between Rhizobium inoculation and sodium benzoate resulted in a significant increase in SOD enzyme activity in plant roots.