Physiological and biochemical responses of mung bean exposed to different concentrations of nano-CeO2

Abstract

Cerium oxide nanoparticles (CeO₂-NPs) are widely used across sectors, including agriculture. However, their overuse has led to environmental dispersion, raising concerns about adverse effects on crops and human health via the food chain. This study investigates the physiological, biochemical, and ultrastructural effects of CeO₂-NPs on mung bean (Vigna radiata L.) under greenhouse and semi-natural conditions. The results reveal both beneficial and harmful impacts, highlighting the need for caution in their application. Foliar spraying of CeO₂-NPs elicited dose-dependent responses. In the greenhouse, 500 mg L⁻¹ significantly increased superoxide dismutase (720 %) and proline accumulation (223 %). Under semi-natural conditions, the same dose enhanced shoot dry weight by 27.1 % compared to the control (p ≤ 0.05). In contrast, exposure to 1000 mg L⁻¹ elevated hydrogen peroxide (50 %) and lipid peroxidation (137 %), reduced chlorophyll (20 %), disrupted cellular ultrastructure, and impaired nitrogen fixation, leading to chlorosis and necrosis. This dose also caused significant reductions in dry weight (18.4 % in greenhouse, 25.4 % in semi-natural) and grain yield (55.9 %) (p ≤ 0.05). Root nodulation was significantly reduced at all tested concentrations (250, 500, 1000 mg L⁻¹), suggesting a toxicity threshold below 250 mg L⁻¹. Seed quality was adversely affected, as shown by decreased iron and zinc levels and increased cerium accumulation (p ≤ 0.05). These findings offer essential insights into the potential risks of CeO₂-NPs in leguminous crops, with implications for food safety and sustainable agriculture.