Synergistic effects of biochar and silicon dioxide nanoparticles abate cadmium uptake and oxidative stress in tomato: Achieving crop resilience and environmental sustainability

Abstract

Cadmium (Cd) contamination of agricultural soils pose a significant threat to food safety, particularly through its accumulation in food chains. This issue highlights the pressing need for effective and innovative mitigation strategies. The application of biochar nanoparticles (BC NPs) and silicon dioxide nanoparticles (SiO₂ NPs) would be an innovative solution in alleviating Cd-induced phytotoxicity. A greenhouse experiment was conducted to evaluate the influence of BC NPs and SiO₂ NPs, both individually and in combination, on Cd mobility/bioavailability in soil and its subsequent bioaccumulation in tomato (Solanum lycopersicum L). Results showed that BC NPs and SiO₂ NPs were effective in reducing Cd uptake in tomatoes and improving plant growth characteristics. However, when BC NPs were combined with SiO₂ NPs, maximum reduction in Cd uptake and improvement in plant growth characteristics was achieved. The study results indicated that soil application of BC+SiO₂ NPs composite at 1.5 % in T5 treatment resulted in a significant increase in plant height (25.6 %), root length (36.9 %), shoot dry weight (43.7 %), root dry weight (95.8 %), and fruit number (133 %), respectively, as compared to control. The T5 treatment also effectively shielded the photosynthetic apparatus of tomato plants, resulting in notable enhancement of photosynthesis by 29 %, transpiration by 91 %, intercellular CO₂ levels by 28.9 %, and stomatal conductance by 27.1 %, respectively, compared to control group. Additionally, the same treatment alleviated Cd-induced oxidative stress by elevating the activities of key antioxidant enzymes i.e., catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) by 22.9 %, 27.9 %, and 13.4 %, respectively, compared to non-amended plants of control treatment. Our findings also illustrated that T5 treatment significantly reduced the bioaccumulation of Cd in plant roots, shoots, and fruits by 28.6 %, 36.2 %, and 70.3 %, respectively, in comparison to plants cultivated in control treatment. Furthermore, the incorporation of BC+SiO₂ NPs composite markedly enhanced the quality attributes of tomatoes relative to other treatments. Collectively, these findings present a novel approach to mitigate Cd toxicity in tomato plants, thereby fostering improved crop yield and fruit quality, which has implications for food security, environmental sustainability and public health.

Keywords: Antioxidant enzymes; Biochar NPs and SiO(2) NPs synergism; Cd contamination; Environmental Sustainability; Food security; Phytotoxicity.