Enhancing spinach growth and soil microbial health under sulfadiazine and polypropylene exposure through zinc fortification

Antibiotics and microplastics have gained significant global attention due to their adverse impacts on ecosystems. Microplastics (MPs) can enter the soil through various pathways, altering the soil and plants physicochemical properties. This study demonstrates that ZnO nanoparticles (200 mg L −1 ) effectively alleviate sulfadiazine (SDZ 10, 25 mg Kg −1 ) and polypropylene (PP 150, 200 mg Kg −1 ) toxicity by enhancing nutrient uptake and promoting spinach growth. ZnO NPs reduced the malondialdehyde levels by 21 % and 22 %, hydrogen peroxide 27 % and 23 %, and electrolyte leakage 28 % and 18 % while increasing superoxide dismutase 25 % and 15 %, peroxidase 22 % and 19 %, catalase 17 % and 18 %, and ascorbate peroxidase 12 % and 17 % in roots and shoots respectively, compared to the control. Similarly, ZnO NPs increased Zn 20 % and 32 %, Fe 43 % and 42 %, Mg 28 % and 22 %, Mn 33 % and 32 %, and K 41 % and 25 % in roots and shoots respectively under combined SDZ+PP stress. Additionally, a low dose of SDZ stress impacts soil microbial diversity, community composition, and metabolic function more severely than a high dose. Furthermore, the combined SDZ and PP stress with ZnO application significantly positively affected soil microbial diversity, community composition, and metabolic functions. • SDZ and PP co-toxicity significantly declined the growth by producing ROS species. • ZnO NPs regulated the defense system by increasing nutrient uptake and boosting growth. • Lower SDZ significantly altered alpha diversity compared to higher SDZ. • SDZ and PS prominently altered the alpha and beta diversity compared to their combination. • ZnO NPs significantly boosted microbial growth under alone and combined SDZ and PS stress.