The present study was aimed to investigate the effect of silicon nanoparticles (SiNp) against Cr (VI) phytotoxicity in pea seedlings. Results show that Cr(VI, 100 μM) significantly (P < 0.05) declined growth of pea which was accompanied by the enhanced level of Cr. Additionally, photosynthetic pigments and chlorophyll fluorescence parameters like Fv/Fm, Fv/F0 and qP were decreased while NPQ significantly (P < 0.05) increased under Cr(VI) treatment. Superoxide radical, hydrogen peroxide and malondialdehyde (MDA-lipid peroxidation) contents were enhanced by Cr(VI). Activities of antioxidant enzymes like superoxide dismutase and ascorbate peroxidase were increased by Cr (VI) while activities of catalase, glutathione reductase and dehydroascorbate reductase were inhibited significantly (P < 0.05). Micro and macronutrients also show decreasing trends (except S) under Cr(VI) treatment. However, addition of SiNp together with Cr(VI) protects pea seedlings against Cr(VI) phytotoxicity hence improved growth was noticed. In conclusion, the results of this study show that Cr(VI) causes negative impact on pea seedlings, however; SiNp protects pea seedlings against Cr(VI) phytotoxicity by reducing Cr accumulation and oxidative stress, and up-regulating antioxidant defense system and nutrient elements.

Silicon nanoparticles (SiNp) alleviate chromium (VI) phytotoxicity in Pisum sativum (L.) seedlings