Morphological and physiological response of green bean plant to foliar application of citric acid and hydrogen sulfide under nanosilver stress

Increasing use of silver nanoparticles in agriculture and industry attracted more attention to the negative effects of their accumulation in environment. In this study, the effect of citric acid and hydrogen sulfide treatment on the morphological and physiological responses of green bean plants under silver nanoparticles stress was investigated. The results showed that nanosilver stress significantly reduced leaf area, plant height, leaf and pod dry weights and made a significant increase in total flavonoids and anthocyanins content and superoxide dismutase and glutathione-S transferase activities. Nanosilver stress increased malondialdehyde content and electrolyte leakage indicating a high oxidative and cell membrane damage, whereas these values ​​were lower in plants treated with citric acid and hydrogen sulfide. Furthermore, the highest growth indices were observed in control plants, plants treated with inducers and plants under stress, respectively, which indicates the effective role of inducers in stress relief. These results showed that citric acid and hydrogen sulfide mitigated the damage caused by nanosilver stress in green bean plants by reducing free oxygen species accumulation and preventing lipid peroxidation leading to increased growth rate in stressed plants. These findings can be used to reduce crop damages in regions contaminated with nanoparticles.