APPLICATION OF BIO-SYNTHESIZED SELENIUM NANOPARTICLES TO MITIGATE CADMIUM STRESS ON TOMATO PLANTS

Abstract

The increasing accumulation of heavy metals (HMs) in agricultural soils poses a significant and multifaceted environmental threat with detrimental consequences for crop yield and the safety of our food supply. Cadmium (Cd), among other HMs, is notorious for its detrimental impact on plants, resulting in decreased growth and compromised agricultural productivity. In response to this challenge, nanotechnology is being used in agriculture for its potential to alleviate heavy metal stress. This thesis presents an investigation into the synthesis of selenium nanoparticles (SeNPs) via an environmentally friendly route utilizing citrus peels as well as their subsequent utilisation on tomato plants exposed to cadmium stress. The experimental setup had three main groups; control, Cd 25, and Cd 50 groups, with two levels of Cd-induced stress; Cd 25 mg/kg and Cd 50 mg/kg. Furthermore, these groups were subjected to SeNPs treatment three times; 5 mg L-1 and 10 mg L-1, during their critical growth stages at the 7th, 8th, and 9th weeks. This multidimensional design facilitated a comprehensive examination of the possible impacts of SeNPs on various physiological and chemical parameters, including growth, photosynthetic capacity, and antioxidant activity. Application of 5 mg L-1 bio-SeNPs significantly (p < 0.05) improved the plant growth through increased chlorophyll content, and improved membrane stability, along with a strengthened antioxidant defense system (enhanced CAT, SOD, POD content). The findings collectively suggest that the efficacy of SeNPs is contingent upon their concentration, with smaller doses demonstrating greater advantages, while larger concentrations pose a potential danger of phytotoxicity. Further research under field conditions is essential for practical SeNPs applications in heavy metal-contaminated soils.