Bio-effects And Mechanisms Of Several Nano-oxide Materials

Nanomaterials (NMs) will inevitably enter into the environment via air, water and soil pathway, during their production application in industry and agriculture. NMs may be potentially harmful to the ecological environment due to their unique physicochemical properties.Therefore; more caution should be paid on the environmental and ecological effects ofthe NMs.In this paper, we studied three nanomaterialsincluding nano ceria oxide, nano silicon oxie and nano iron oxide. The tested plants are lettuce, cherry radish and ricecultured in the greenhouse to study nanomaterials effect on growth, uptake, biotransformation, physicology, microbial community structure enzyme activty, hormone.The main works and results are as follows:(1) Butterhead lettuce were germinatedand grown in potting soil for 30 days cultivation with treatments of 0,50,100,1000 mg CeO2 NPs per kg soil. Results showed that lettuce in 100 mg/kg treated groups grew significantlyfaster than others, but significantly increased nitrate content. The lower concentrations treatment had no impact on plant growth, compared with the control. However, the higher concentration treatment significantly deterred plant growth and biomass production. The stress response of lettuce plants, such as Superoxide dismutase (SOD), Peroxidase (POD), Malondialdehyde (MDA) activity was disrupted by 1000 mg/kg CeO2 NPs treatment. In addition, the presence of Ce (III) in the roots of butterhead lettuce explained the reason of CeO2 NPs phytotoxicity. These findings demonstrate CeO2 NPs modification of nutritional quality, antioxidant defense system, the possible transfer into the food chain and biotransformation in vivo.(2) To test, we cultivated radish in CeO2 NPs-amended soils across series of concentrations treatment (control,10 mg/kg,50 mg/kg,100 mg/kg CeO2 NPs). Following cultivation, the results implied that CeO2 NPs accelerating the production of radish plant and enhancing the relative chlorophyll content during 40 and 50 cultivation days. Moreover, the diversity of soil bacterial community was altered by CeO2 NPs-amended soil, especially a new species of bacteria (Bacillus megaterium) emerged, which could dissolve organic phosphorus, we inferred the essence of the bacteria that cherry radish root absorbed phosphorus, promoting the growth. CeO2 NPs mostly absorbed by root, andimproved the activity of antioxidant enzyme system to scavenge the damage of free radicals in radish root and leaf.(3)Under solution culture amended different concentration of nano SiO2 and bulk SiO2 (50 mg/L, 250 mg/L and 1000 mg/L), no effects on growth were observed,the biomass and chlorophyll relativecontent was not significant changed. Rice root epiderinis was adsorbed by concentration of 1000 mg/L nano SiO2, while 1000 mg/L nano SiO2 and bulk SiO2 have significantly decreased the content of ABA, delay the plant aging, but the IAA content was not significantly changed.(4) Under solution culture amended different concentration of γ-Fe2O3 nanomaterials (2 mg/L,20 mg/L and 200 mg/L), the results suggested LRK1 transgenic and non-transgenic 93-11 rice plants were not influenced by the nanomaterials. The biomass and chlorophyll relativecontent was not significant changed, butenzyme activityand the concentration of two phytohormones, abscisic acid (ABA) andindole-3-acetic acid (IAA) generated change, Root phytohormone inhibition was positively correlated with Fe2O3 NP concentrations, indicating that Fe2O3 had a significant influence on the production of these hormones. LRK1 transgenic was more sensitive than non-transgenic 93-11 rice plants. The activities of antioxidant enzymes were significantly higher as afactor of low Fe2O3 NP treatment concentration and significantly lower at high NP concentrations, but only among transgenic plants. The lipid peroxide was not significantly accumulated.