| Cadmium pollution in the environment is becoming more and more serious,especially due to the use of chemical fertilizers and pesticides,sewage discharge and other reasons,so the situation of cadmium pollution in the soil is getting more and more attention.Rice is one of the major food products in China and one of the major crops that can easily absorb and accumulate cadmium.Due to the influence of cadmium pollution in soil and water,cadmium pollution in rice is still a serious problem.Nanotechnology has been applied more and more widely in agricultural production.Nanoparticles and nano powders have been used to control toxic heavy metals.The repair of cadmium by zinc oxide nanoparticles has also received increasing attention and research from scholars.Taking rice Liangyou 8106 as test materials,by nutrient solution culture and soil pot experiment in two ways.Add different concentrations of zinc oxide nanoparticles e to the cadmium-containing nutrient solution and soil to study the growth physiological status of rice,the change of heavy metal content,the change of cadmium form in soil and its mechanism of action.Provide reference and scientific basis for the treatment of cadmium pollution in rice in cadmium-contaminated areas.The main research contents and results are as follows:1.The effect of zinc oxide nanoparticles on alleviating cadmium stress in early growth of rice seedlings was studied by nutrient solution culture.Under the condition of cadmium pollution(5mg/L),rice seedlings were treated for seven day with different concentrations of zinc oxide nanoparticles(10mg/L,20mg/L,50mg/L,100mg/L and 200mg/L).The results showed that 5mg/L cadmium was toxic to rice,which was proved by its biomass and antioxidant enzyme activity.The addition of 50mg/L zinc oxide nanoparticles increased the dry weight of overground part of rice seedlings,and the addition of 100mg/L and 200mg/L zinc oxide nanoparticles increased the dry weight of overground part and root of rice seedlings.Compared with cadmium treatment alone,adding zinc oxide nanoparticles can improve superoxide dismutase(SOD)activity(50mg/L,100mg/L and 200mg/L zinc oxide nanoparticles treatment)and catalase(CAT)activity(20mg/L,50mg/L,100mg/L and 200mg/L zinc oxide nanoparticles treatment)in rice leaves,increasing 21.21% to 37.69% and 13.79% to 66.09%,respectively,while reducing malondialdehyde(MDA)content in leaves.In addition,the addition of 10-200mg/L zinc oxide nanoparticles reduced the cadmium content in the root of rice seedlings(10.12%-34.82%),and the addition of zinc oxide nanoparticles(50mg/L,100mg/L and 200mg/L zinc oxide nanoparticles)also reduced the cadmium content in the overground part(26.97%-60.86%),and the zinc concentration in rice seedlings increased with the increase of zinc oxide nanoparticles concentration.Therefore,a certain concentration of zinc oxide nanoparticles can alleviate the cadmium stress of rice.2.The results of nutrient solution culture test showed that zinc oxide nanoparticles had a mitigation effect on cadmium toxicity in rice.Therefore,based on the analysis of nutrient solution culture test results,soil pot experiment was conducted to study the influence of different concentrations of zinc oxide nanoparticles on cadmium absorption in rice and the change of cadmium morphology in soil.The results showed that the influence of zinc oxide nanoparticles on cadmium absorption in rice in seedling stage was greater than that in mature stage,and the addition of 10 to 100mg/kg zinc oxide nanoparticles could increase the biomass and chlorophyll content of rice in seedling stage and reduce the cadmium content in rice.With the accumulation of culture time,compared with the control group(CK),zinc oxide nanoparticles had no significant effect on dry weight of straw at the maturity stage of rice(p>,0.05),while 50mg/kg zinc oxide nanoparticles increased root dry weight,10mg/kg and 20mg/kg zinc oxide nanoparticles increased grain dry weight.Compared with CK,the addition of zinc oxide nanoparticles had no significant effect on the cadmium content in straw and roots(P>,0.05),while the cadmium content in grains was significantly reduced(P<0.05),with a decrease of 20.39-31.91%.By analyzing soil cadmium forms,of cadmium in soil is given priority to,the second,and the attitude of residue,iron,manganese oxidation state,carbonate state and proportion of the organic combination state minimum,zinc oxide nanoparticles influence on soil Eh value is bigger,the addition of zinc oxide nanoparticles reduced soil Eh value,make the active state of cadmium to residue state so as to reduce the accumulation of cadmium in rice grain.The results of this part of experiment are helpful for us to further understand the influence of zinc oxide nanoparticles on the environmental behavior of cadmium in agricultural soil. |
