Silicon nanoparticles decrease arsenic translocation and mitigate phytotoxicity in tomato plants

In this study we simulate the irrigation of tomato plants with As contaminated water (from 0 to 3.2 mg L-1) and investigate the effect of the application of silicon nanoparticle (Si NPs) in form of silicon dioxide (0, 250 and 1000 mg L-1) on As uptake and stress. Arsenics concentrations were determined in substrate and plant tissue at three different stratums. Phytotoxicity, As accumulation and translocation, photosynthetic pigments and antioxidant activity of enzymatic and non-enzymatic compounds were also determined. Irrigation of tomato plants with As contaminated water caused As substrate enrichment and As bioaccumulation (roots > leaves > steam) showing that the higher the concentration in irrigation water, the farther the contaminant flowed and translocated through the different tomato stratums. Phytotoxicity was observed at low concentrations of As, while tomato yield increases increased at high concentrations. Application of Si NPs decreases As translocation, tomato yield, and root biomass. Increased production of photosynthetic pigments and improved enzymatic activity (CAT and APX) suggested tomato plant adaptation at high As concentrations in the presence of Si NPs. Our results reveal likely impacts of As and nanoparticles on tomato production in places where As in groundwater is common and might represent a risk.