| Mercury(Hg)is the only heavy metal that can exist as a liquid at room temperature.Mercury is highly toxic and can be transported over long distances,which has been listed as a priority pollutant.China is rich in mercury resources,and at the same time,mercury mining has left serious environmental pollution problems.Rice is an important food crop and an important mercury-rich crop.Compared with total mercury(THg),methylmercury(Me Hg)is more likely to be concentrated in the edible rice parts of rice.Therefore,studying the migration law of mercury in rice is of practical significance to inhibit the migration of mercury to edible rice.In response to the above problems,a mercury pollution simulation greenhouse pot experiment was designed with rice as a host plant and a mixed strain of Glomus mosseae(BGC BJ05A)and Glomus etunicatum(BGC XJ04B)as the inoculum.The growth and physiological conditions of plants,the absorption and transport of mercury in various organs of rice,and the rhizosphere environment were studied by comparative experiments between the inoculated and uninoculated groups.Based on the pot experiment,the effect of arbuscular mycorrhizal fungi on the absorption and accumulation of mercury by rice were illustrated.The purpose of this study was to study the influence of soil microorganisms on the migration of mercury in rice-soil system,and to provide a theoretical basis for the study of arbuscular mycorrhizal fungi to reduce the risk of mercury exposure in rice.The main results of this study were as follows:(1)The greenhouse pot experiment found that under the condition of mercury pollution,rice could form a good symbiotic relationship with arbuscular mycorrhizal fungi,and the mycorrhizal infection rate was 15.54%～24.04%.(2)The effects of mercury on the growth and physiological characteristics of rice after inoculation with arbuscular mycorrhizal fungi were studied through pot experiments.The results showed that after inoculation with arbuscular mycorrhizal fungi,rice biomass and plant height increased by 14.37%～79.35% and 4.98%～10.13%,respectively.The chlorophyll content and photosynthetic rate of rice leaves increased by 5.33%～18.27% and 16.65%～50.40%,respectively.The content of nitrogen and phosphorus in rice leaves increased by 10.83%～66.90% and 2.38%～16.35%,respectively.The MDA content of rice reduced by 8.22% to 27.42%.The activities of SOD,CAT,POD,and APX in rice leaves increased by 3.99%～10.35%,5.44%～12.98%,5.90%～15.82%,and 2.84%～13.48%,respectively.The result showed that arbuscular mycorrhizal fungi can reduce the toxic effects of heavy metals on the growth of rice and affect the growth of rice.(3)The effects of arbuscular mycorrhizal fungi on the absorption and transport of mercury in rice were studied by pot experiment.The results showed that after inoculation with arbuscular mycorrhizal fungi,the contents of total mercury and methylmercury in rice reduced by 8.80%～93.02% and 42.93%～96.97%,respectively.The transfer coefficients of methylmercury from roots,stems,and leaves to paddy rice reduced by 87.73%～94.24%,96.02%～98.32%,and 95.94%～99.14%,respectively.The ratio of methylmercury in rice to total rice mercury decreased by 56.57%,35.63%,and7.26%,respectively.It showed that arbuscular mycorrhizal fungi inhibited the absorption of methylmercury in rice,and at the same time,arbuscular mycorrhizal fungi could inhibit the transfer of methylmercury to paddy rice.(4)The effect of inoculation of arbuscular mycorrhizal fungi on the physical and chemical properties of rice rhizosphere soil was explored through pot experiments.The results showed that: under the condition of mercury stress,after inoculation with arbuscular mycorrhizal fungi,the p H of rice rhizosphere soil increased by 2.52%～4.80%,which showed that arbuscular mycorrhizal fungi can change the effectiveness of mercury in the soil by changing the physical and chemical environment of the rhizosphere,thereby inhibiting the absorption of mercury by rice. |
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