Modulating Physiological and Antioxidant Responses in Wheat Cultivars via Foliar Application of Silicon Nanoparticles (SiNPs) Under Arsenic Stress Conditions

Globally, heavy metals especially arsenic (As) toxicity in staple crops like wheat has posed serious threats to human health, necessitating conducting fresh studies to find out biologically viable As toxicity mitigation strategies. Therefore, this study aimed to investigate the impact of foliar-applied silicon nanoparticles (SiNPs) at the tillering stage on the activation of physiological and antioxidant regulation in wheat to induce tolerance against varying As toxicity levels. The trial comprised two promising wheat cultivars (Anaaj and Ghazi) and five SiNPs regimes including 0, 30, 60, 90, and 120 ppm doses against As toxicity levels of 0 and 25 ppm. The recorded findings depicted that SiNPs regimes significantly improved morphological characteristics such as root length, fresh and dry weight, as well as shoot length, and fresh and dry weight of wheat cultivars. Additionally, the levels of chlorophyll pigments, including chlorophyll a, chlorophyll b, and total chlorophyll contents, were significantly increased in SiNPs-treated plants, indicating improved photosynthetic activity. The enhanced antioxidant enzyme activities, such as ascorbate peroxidase (APX), superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), played a vital role in combating oxidative stress induced by As toxicity. Moreover, SiNPs application resulted in a significant reduction in As concentration in both leaves and roots, highlighting the ability of SiNPs to regulate the uptake and accumulation of arsenic and mitigate its toxic effects. In conclusion, the foliar application of SiNPs during the tillering stage of wheat effectively activated physiological and antioxidant regulation, leading to enhanced tolerance against As toxicity.