Study On The Toxicity Of ZnO NPs To Wheat And Its Relationship With Culture Conditions And Growth Stages

Nowadays,Zinc Oxide nanoparticles(ZnO NPs)is one of the most widely used nanomaterials which has provided big opportunities for a wide variety of applications in the fields of physics,chemical industry,feed industry,coating industry and textile industry.However,with the increasing application in life,ZnO NPs will have more opportunities to contact with the animals,plants and human.Some studies have shown that ZnO NPs has obvious toxicity to bacteria,animals and plants,so it is necessary to study and evaluate the biological safety of ZnO NPs.Previous reports have shown the biological toxicity of ZnO NPs but there are no reports about the toxicity of ZnO NPs to different growth stages of wheat.In addition,it is also need a lot of research datas and reasonable research methods to provide help for the toxicity mechanism of ZnO NPs which is not clear.In this paper,the wheat related to human closely was choosen as the object of ZnO NPs.At first,the effects of ZnO NPs(particle size of 5 nm)on the root length,seedling height,growth rate and morphology of wheat root were studied.We found that ZnO NPs had significant toxicity to root length,plant height and root length.When the concentration of ZnO was 20 mg/L,there was a significant inhibitory effect on root length of wheat.The ZnO NPs in high concentration showed effect on the root length,plant height and the root growth rate of wheat significantly.In addition,the toxicity of Zn O NPs to different growth stages of wheat was studied.The ZnO NPs was applied with three growth stages which are imbibition stage,protrusion stage and germination stage separately.We found that ZnO NPs had the highest toxicity to wheat in germination stage and the lowest toxicity in imbibition stage.This is a result of the ZnO NPs absorbed on the epidermis of wheat seed and the aggregation of ZnO NPs.The toxicity of ZnO NPs was different with filter paper and without filter paper.With the filter paper in culture medium,the toxicity of ZnO NPs was almost disappeared,which indicated that the culture environment had a great influence to the toxicity of ZnO NPs.Nevertheless,there is no obvious relationship between the filter paper and the toxicity of ZnSO4-7H2 O to wheat.This shows that the toxicity mechanism of the ZnO NPs is not related to the Zn2+ released by ZnO NPs,but the properties of the particle itself.