Harnessing nano-engineered iron-silicon nanoparticles to modulate cadmium uptake and strengthen detoxification in rice ( Oryza sativa L.)

Cadmium (Cd) is a highly toxic and mobile heavy metal in soils, adversely affecting rice quality and productivity. Innovations in technology/techniques are needed to reduce Cd accumulation in rice while improving its resilience to contamination. The current study focused on preparing, characterizing, and evaluating silicon dioxide nanoparticles (SIONPs), iron oxide nanoparticles (IONPs), and iron-doped silicon nanoparticles (IDSNPs) for their potential to improve rice resilience to Cd contamination. Soil was supplemented with SIONPs, IONPs and IDSNPs at 1% and 2% w/w. Results illustrated that the most significant improvements in plant growth were observed with 2% IDSNPs, where shoot dry weight, root dry weight, root length, and shoot length increased by 38%, 42%, 53.3%, and 27%, respectively. In a similar manner, the same treatment led to significant increases in photosynthesis rate, internal CO2 levels, stomatal conductance, and transpiration rates, with increases of 20.9%, 18.8%, 126.6%, and 22.8%, respectively. T6 treatment suppressed Cd-induced oxidative stress in rice plants by boosting APX, SOD, and CAT activities by 36.3%, 76.8%, and 41.5%, respectively. Moreover, T6 treatment modulated phytohormone levels and reduced gene expression associated with Cd transport. It was noteworthy that OsNRAMP5 levels decreased significantly both in roots and shoots, with decreases of 49.5% in roots and 53.7% in shoots in T6-treated plants. Soil supplementation with the highest level of IDSNPs significantly reduced the uptake of Cd by rice. The Cd uptake in rice roots treated with T6 decreased by 19.3%, whereas the reduction in stems and leaves was 31.2% and 29.9%, respectively. Our study demonstrated that IDSNPs represent an environmentally friendly and sustainable approach for in-situ remediation of Cd contaminated soils. This method supports continued agricultural production on Cd-affected lands without costly or disruptive practices. Globally, such nanotechnology-based interventions can promote safer food production, improved soil health, reduced public health risks, and sustainable agricultural development.