Abstract

Cadmium (Cd) contamination, especially in heavy metals, poses a substantial risk to agricultural productivity and food safety. Although zinc oxide nanoparticles (ZnO NPs) have demonstrated potential in reducing the harmful effects of cadmium toxicity, their specific impact on plant biochemical and physiological processes has not been extensively investigated. This research examined the possibility of using 100 mg. kg-1 ZnO NPs (foliar application) to reduce Cd stress (100 mg. kg-1, applied to the roots) in two different varieties of tomato plants. A completely randomized design (CRD) was used, with four treatments: control, ZnO NPs, Cd stress and ZnO NPs +Cd interaction, each replicated five times. Growth parameters (fresh and dry biomass), photosynthetic pigments (chlorophyll a, b and total), biochemical attributes (soluble proteins, free amino acids, carbohydrates) and Cd accumulation in fruit were assessed. The results indicate that ZnO NPs significantly alleviated Cd toxicity, leading to a 35% increase in root biomass, 25% enhancement in soluble proteins and 20% higher chlorophyll content in combination as compared to Cd stress alone. Notably, ZnO NPs significantly decreased the accumulation of Cd in fruits by up to 85%, underscoring their potential in enhancing food safety. Principal component analysis (PCA) and correlation analysis provided additional evidence of strong positive connections between the use of ZnO NPs, enhanced biochemical responses and decreased Cd uptake. These findings indicate that ZnO NPs can be a valuable approach for reducing heavy metal toxicity in crops, which has important implications for sustainable farming practices and ensuring food security. Future studies should investigate the long-term impacts of ZnO NPs on plant growth, metabolism and potential nanoparticle bioaccumulation risks to ensure their safe application in agriculture.