Influences of Cerium Oxide Nanoparticles and Salinity on Common Bean (Phaseolus Vulgaris) Growth, Physiology, and Root System Architectural and Anatomical Traits

Engineered nanoparticles (ENPs) have emerged as global pollutants due to their extensive use across various industries, raising particular concerns in agricultural settings. This study addresses the understudied interactions between ENPs, specifically cerium oxide nanoparticles (CeO₂NPs), and sodium chloride (NaCl) in agricultural crops, within the context of widespread soil salinization. 'Pinto' common bean seedlings were cultivated in sand-filled pots under greenhouse conditions, following a completely randomized experimental design for one month. Four treatments were administered: (1) control with no NaCl and no CeO₂NPs, (2) 50 mM NaCl without CeO₂NPs, (3) 200 mg kg CeO₂NPs without NaCl, and (4) a combination of 50 mM NaCl and 200 mg kg CeO₂NPs. Weekly measurements were conducted, and a random cohort of 20 plants, including 5 from each treatment, was destructively sampled. At the experiment's conclusion, the final cohort was dissected into above- and below-ground organs to determine the concentrations of Ce and Na, and root scans were performed to analyze root system architectural traits. The results revealed significant differences in growth including root system architecture (including length, surface area, and volume), anatomical traits, biomass (fresh and dry), and vine length. Similarly, significant differences were observed in fluorescence; Ce and Na concentrations; electrolyte leakage, with the CeONPs + NaCl treatment having 3.3-fold more leakage than the control; and chlorophyll contents, with the CeONPs treatment having 3.3-fold more chlorophyll a than the NaCl treatment. Additionally, notable interactions between NaCl and CeO₂NPs were observed in root apoplastic barrier formation, vine length, Ce uptake, and chlorophyll content and fluorescence.