Mechanism of Nanosilicon-Mediated Alleviation of Salinity Stress in Faba Bean (Vicia faba L.) Plants

Aims: In the current study we try to clarify the mechanism that might be involved in the ameliorating effects of Nano-silicon (NSi) and Silicon (Si) on faba bean (Vicia faba) plants grown under different levels of salinity stress that we found in a previous study.
Study Design: Factorial completely randomized design Pot experiments were used with NSi and Si applied at 4 concentrations each (0, 1, 2 and 3 mM) and NaCl (0, 50, 100 and 200 mM) were studied.
Place and Duration of Study: Experiments were carried out in the greenhouse of the Experimental Station, Faculty of Science, Princess Nora Bint Abdulrahman University, Kingdom of Saudi Arabia during winter season of 2012/2013.
Methodology: Effects of NSi and Si on membrane characteristics, photosynthetic pigments, sugar content, free proline, antioxidant enzymes and mineral elements were investigated in NaCl stressed and non-stressed faba bean plants. The experiment was arranged in a factorial design with 4 replications at NaCl levels of 0, 50, 100 and 200 mM. The tested NSi and Si concentrations were 0, 1, 2 and 3 mM for each.
Results: NaCl treatments caused an increase in proline content and in some enzyme activities, Chl a, b and carotenoids were decreased. Application of NSi caused a significantly increase in the activity of ascorbate peroxidase (APX), catalase (CAT) and peroxidase (POD) in plant leaves, but caused a decrease in the activity of superoxide dismutase (SOD) as compared to unstressed plants.
Oxidative damage, produced by salinity stress, seemed to decrease in accordance with the increase in antioxidant enzymes activity under NSi and Si treatments, thus tolerance against salt stress was observed. The improvement of salt tolerance resulted from NSi and Si treatments was accompanied with improved membrane stability, chloroplast formation and sugar accumulation.
Conclusion: Nano-silicon treatments can reduce the adverse effects of salinity on V. faba plants by enhancing the activity of antioxidant enzymes.