Silicon Nanoparticle Ameliorates Cadmium Toxicity in Rice By Minimizing Phytotoxic and Genotoxic Effects

Abstract

Carcinogenic cadmium (Cd) is the 7th most hazardous element, lowering crop yield, and posing health hazards through trophic transfer. The grain of life, rice, is a significant source of oral Cd intake. Nanoparticles augment plant resilience by intensifying bio-physiological responses. 7 days old rice seedlings (var. Maharaj and Khitish) were subjected to CdCl₂ (10 µM) with simultaneous application of silicon dioxide nanoparticles (SiO₂NPs; 2.5 ppm) through hydroponics and by foliar spray for additional 7 days. At 14 days of growth, we evaluated different physio-biochemical and genotoxicity indicators. Our study revealed that SiO₂NPs could alleviate Cd induced phytotoxicity by upscaling root-shoot length, chlorophyll contents, hill activity, antioxidant activities (superoxide dismutase, catalase, phenol) and decreasing endogenous hydrogen peroxide content via both methods but hydroponic application had greater benefits. In histochemical study, Cd-treated leaves showed intensified blue colour with NBT indicating ROS localization. Genotoxicity study by RAPD confirmed that SiO₂NPs could mitigate genotoxic stress with minor impact at genomic DNA level, reflecting higher genomic template stability. Additionally, polymorphism was less pronounced in Cd + NP treated sets than in Cd treated counterpart. Sole Cd content of SiO₂NPs treated plants also decreased. Nonetheless, SiO₂NPs hydroponics followed by foliar was the most accepted application route in enhancement of antioxidant defence and reduction of stress markers, Cd contents in rice. Hence, we conclude that nano Si addition can be a favourable and useful technique in attenuating Cd stress in rice, offering a promising role in modern agriculture for optimal plant growth.