Cobalt ferrite nanoparticles mitigate cadmium and lead toxicity in tomato (Solanum lycopersicum L.) by enhancing antioxidant defense and nutrient homeostasis

BACKGROUND: Heavy metal pollution, particularly from cadmium (Cd) and lead (Pb), poses a significant risk to agricultural productivity and food quality by affecting plant growth, nutritional composition, and redox balance. This study aimed to evaluate the effectiveness of cobalt ferrite nanoparticles (CoFe₂O₄ NPs) in reducing the harmful effects of Pb and Cd on tomato plants. After exposure to 100 mg L⁻¹ of either Cd or Pb, tomato seedlings were treated with 40 and 80 mg L⁻¹ of CoFe₂O₄ NPs. RESULTS: Heavy metal stress adversely affected various parameters, including growth, photosynthetic efficiency, water content, and nutrient levels (N, P, K). However, the application of CoFe₂O₄ nanoparticles, especially at 40 mg L⁻¹, significantly alleviated these negative impacts. Treated plants showed improved growth, enhanced nutrient uptake, increased chlorophyll content, and better water status compared to untreated ones. Additionally, CoFe₂O₄ nanoparticles increased proline, phenolics, and key enzymes like glutathione reductase (GR) and catalase (CAT). They also reduced levels of reactive oxygen species (ROS), lipid peroxidation, electrolyte leakage, and cadmium/lead (Cd/Pb) concentrations in plant tissues. Multivariate analyses, such as PCA, highlighted the protective effects of these nanoparticles against heavy metal stress. CONCLUSIONS: Cobalt ferrite nanoparticles could successfully reduce the toxic effects of both cadmium and lead in tomato plants through their positive influence on growth, photosynthesis efficiency, nutrient absorption, and the antioxidative system of plants. Based on the results, it can be concluded that CoFe₂O₄ nanoparticles can serve as an environmentally friendly tool of nanotechnology to improve crops' efficiency.