Effects Of Arbuscular Mycorrhizal Fungi On Root Characteristics Of Two Maize Varieties And Cadmium-lead Migration In Soil

Arbuscular mycorrhiza fungi(AMF)are symbiotic bacteria colonized in plant roots,which have significant effects on plant root growth,plant heavy metal accumulation and soil heavy metal migration.However,whether AMF affects soil plant system heavy metal migration through regulating root morphology remains unclear.The study selected two maize varieties with well-developed roots(Hongwei No.1)and underdeveloped roots(Zhouyu 0913)as the research subjects,and conducted indoor soil column culture and leaching experiments to analyze the effects of AMF inoculation on maize growth,root traits,plant Cd/Pb content,soil preferential flow distribution,and Cd leaching.The results indicate that:(1)Inoculation with AMF significantly improved the mineral nutrition,photosynthetic physiology,growth,and Cd/Pb content of two maize varieties,but the improvement effect varied among varieties.Among them,the inoculation of AMF resulted in an increase of24.0% and 26.1% of the phosphorus content in the aerial part of Hongwei 1 and the phosphorus content in the root of Zhouyu 0913,an increase of 24.4% and 72.3% of the net photosynthetic rate of Hongwei 1 and the transpiration of Zhouyu 0913,an increase of 24.7%and 41.8% of the biomass of Hongwei 1 and Zhouyu 0913,respectively,and a decrease of38.0% and 54.8% of the Cd content in the root of Hongwei 1 and Zhouyu 0913,respectively,but led to an increase of 12.7% of the Pb accumulation in the root of Hongwei 1.(2)Inoculation with AMF alters the spatial distribution characteristics of root traits in two maize varieties.In the vertical direction of the soil,the roots of the two corn varieties are mainly distributed in a soil layer of 30-40 cm.The roots of Hongwei 1 and Zhouyu 0913 account for 40.2% and 48.7% of the total root biomass,respectively;Inoculation with AMF resulted in an increase of 88.6% and 62.3% in the number of root tips of Hongwei No.1 and Zhouyu 0913 in a soil layer of 30-40 cm,respectively.At a horizontal distance from the corn plant,the corn roots are mainly distributed in a soil layer of 0-5 cm,with Hongwei No.1 and Zhouyu 0913 accounting for 55.3% and 50.4% of the total root biomass,respectively.In the soil layer,inoculation with AMF resulted in a 66.1% and 1.25 fold increase in the volume of Hongwei No.1 and Zhouyu 0913 roots within a range of 10-15 cm,respectively.(3)Inoculation with AMF significantly affects the distribution of soil preferential flow.The staining test found that solutions at different soil depths flow downward in a funnel or tree like manner,and the phenomenon of soil preferential flow is obvious.Inoculation with AMF resulted in a 5.1% increase in the staining area ratio of jade 0913 in a 0-10 cm soil layer.As the soil depth increased(10-20 cm),the staining area of Hongwei No.1 and Zhouyu 0913 decreased by 42.7% and 42.1% compared to the upper soil(0-10 cm),respectively.(4)Inoculation with AMF significantly reduced the Cd/Pb concentration and leaching loss of soil solution.Inoculation with AMF resulted in a 57.0% decrease in dissolved Cd concentrations in both Hongwei 1 and Zhouyu 0913,while the particulate Cd concentrations in Hongwei 1 and Zhouyu 0913 decreased by 98.4% and 1.02 times,respectively.Inoculation with AMF resulted in a 1.8 fold and 2.6 fold decrease in particulate Pb concentrations in Hongwei 1 and Zhouyu 0913,respectively.The loss of dissolved Pb in Zhouyu 0913 leaching solution decreased by 1.16 times,and the loss of dissolved Pb in Hongwei 1 and Zhouyu 0913 soil decreased by 32.6% and 57.7%,respectively.(5)The correlation analysis shows that the root length density is significantly positively correlated with the accumulation of Pb in the root system within the range of 0-5 cm,5-10 cm,and 10-15 cm horizontally from corn,and significantly negatively correlated with the loss of dissolved and particulate Cd in the leaching solution within the range of 0-5 cm and 10-15 cm.The root surface area density is significantly correlated with the accumulation of Cd/Pb in the root system and the loss of dissolved and particulate Cd in the solution in a vertical soil layer of 20-30 cm.AMF inoculation significantly reduced Cd/Pb content and increased Cd/Pb accumulation through improving mineral nutrition,photosynthetic physiology and growth of the two maize varieties.The simultaneous inoculation of AMF increased the spatial distribution characteristics of root characters of two maize varieties,affected the distribution characteristics of priority flow in soil,and reduced the leaching of Cd.