Effect of nano-silicon on the regulation of ascorbate-glutathione contents, antioxidant defense system and growth of copper stressed wheat (Triticum aestivum L.) seedlings

Copper (Cu 2+ ) toxicity can inhibit plant growth and development. It has been shown that silicon (Si) can relieve Cu 2+ stress. However, it is unclear how Si-nanoparticles (SiNPs) relieve Cu 2+ stress in wheat seedlings. Therefore, the current study was conducted by setting up four treatments: CK, SiNP: (2.5 mM), Cu 2+ : (500 µM), and SiNP+Cu 2+ : (2.5 mM SiNP+500 µM Cu 2+ ) to explore whether SiNPs can alleviate Cu 2+ toxicity in wheat seedlings. The results showed that Cu 2+ stress hampered root and shoot growth and accumulated high Cu 2+ concentrations in roots (45.35 mg/kg) and shoots (25.70 mg/kg) of wheat as compared to control treatment. Moreover, Cu 2+ treatment inhibited photosynthetic traits and chlorophyll contents as well as disturbed the antioxidant defense system by accumulating malondialdehyde (MDA) and hydrogen peroxidase (H 2 O 2 ) contents. However, SiNPs treatment increased root length and shoot height by 15.1% and 22%, respectively, under Cu 2+ toxicity. Moreover, SiNPs application decreased MDA and H 2 O 2 contents by 31.25% and 19.25%, respectively. SiNPs increased non-enzymatic compounds such as ascorbic acid-glutathione (AsA-GSH) and enhanced superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbic peroxidase (APX) activities by 77.5%, 141.7%, 68%, and 80%, respectively. Furthermore, SiNPs decreased Cu 2+ concentrations in shoots by 26.2%, as compared to Cu 2+ treatment alone. The results concluded that SiNPs could alleviate Cu 2+ stress in wheat seedlings. The present investigation may help to increase wheat production in Cu 2+ contaminated soils.