Effects Of Ceria Nanoparticles On Growth,Physiological And Biochemical Parameters And Nutritional Value Of Soil Grown Corn(Zea Mays)

With the extensive application of nanomaterials,a large amount of nanomaterials are released into the environment.Ceria nanoparticle(NP)is one of the most widely used nanoparticles in various fields because of its unique properties.But the researchs on the plant effect of ceria NPs is still limited.Most of the literature has focused on exploring the effects of ceria NPs on plants under short-term hydroponics conditions,and the doses used are much higher than the environmentally relevant levels.Corn,a wide range of crops,was selected as a model in this study.The effects of short-term(28 days after sowing)and long-term(90 days after sowing)exposure of environment-relevant concentrations of ceria NPs(25,75 and 225 mg/kg)on the growth and grain quality of maize plants were studied by combining toxicological methods and synchroradiation techniques.The cerium ion was used as a control to further explore the mechanism.The main results of this study are as follows:(1)The effects of ceria NPs on maize plants varied with the different growth stages,ceria NPs can significantly reduce the growth characteristics such as plant biomass,and affect the absorption of the mineral elements at 28 DAS,but the plant height and biomass increased and the homeostasis of antioxidant defense system in plants was disturbed at 90 DAS.(2)Speciation analysis revealed there was mutual transformation between Ce(Ⅳ)and Ce(Ⅲ)in the soil-plant system.At 90 DAS,in the roots that treated with 225 mg/kg ceria NPs,8.4%of total Ce presented as Ce(Ⅲ);while in the roots that treated with 225 mg/kg Ce3+ions,12.5%of total Ce presented as Ce(Ⅳ).It is speculated that Ce3+ ions play a key role in toxicity.(3)Long-term exposure of ceria NPs may affect the silking of maize heading,resulting in the decrease of yield and the incomplete development of grains,as well as the nutritional quality and flavor of grains.