| As an important regulator of plant production,soil microorganisms play an important role in maintaining soil fertility,improving crop yield and enhancing stress resistance.At the same time,plants can also use root exudates to shape beneficial rhizosphere microbial communities to adapt to the environment.At present,more and more attention has been paid to the agricultural management measures of using soil microorganisms to promote the sustainable and healthy development of agricultural ecosystem.Earthworms can directly or indirectly affect soil microorganisms and change the growth of plants or the interaction between plants and other organisms from bottom to top.However,whether the effect of earthworm on plants will be affected by the type of fertilization has not been reported.Therefore,this study planted maize in the Wuhan and Daye with different kinds of fertilizers(organic fertilizer and chemical fertilizer),and explored the effects of Pheretima guillelmi activity on maize growth,aboveground insect community,soil physical and chemical properties,microbial community and maize root exudates,in order to provide reference for exploring the ecological adaptation mechanism of earthworm activity that affecting soil microorganisms to regulate plants.The main results are as follows:1.The effect of earthworm activity on maize growth and yield is related to the type of fertilizationBy measuring the relevant indexes of maize growth,it was found that earthworm activity could increase the maize yield in Wuhan and Daye by 6.26% and 18.57%respectively under the condition of applying organic fertilizer;When chemical fertilizer was applied,earthworm activity could increase the maize yield in Wuhan and Daye by19.71% and 15.00% respectively.Under the application of different kinds of fertilizers,earthworm activities can significantly improve the SPAD value,plant height,leaf area,shoot biomass and root biomass of maize plants in Daye,but have no significant effect on the growth indexes of maize plants in Wuhan.2.The effect of earthworm activity on aboveground insect community of maize plant is related to the type of fertilizationBy investigating the aboveground insect community of maize,it was found that earthworm activity affected the aboveground insect community of maize plants in Wuhan and had no significant effect on the aboveground insect community structure of maize in Daye under the condition of applying organic fertilizer,but the diversity of aboveground insect community of maize in Wuhan and Daye increased significantly;When chemical fertilizer was applied,earthworm activity had no significant effect on the aboveground insect community of maize in Wuhan and Daye,but the diversity of aboveground insect community of maize plants increased significantly after earthworm was added to Daye.After counting the number of chewing and piercing-sucking mouthparts herbivorous insects on maize plants,it was found that earthworm activity led to a significant increase in the number of chewing mouthparts herbivorous insects on maize in Daye under the application of different kinds of fertilizers.When organic fertilizer was applied,earthworm activity could significantly reduce the number of herbivorous insects in piercing-sucking mouthparts in Wuhan.3.The effects of earthworm activities on soil carbon and nitrogen content and soil microbial composition are related to fertilization typesAfter measuring the physical and chemical properties of soil,it was found that the earthworm activity could significantly increase the contents of total nitrogen and total carbon in the soil of Wuhan by 30.30% and 15.30% respectively compared with the field without earthworm under the condition of applying organic fertilizer,and the content of total carbon in the soil of Daye by 12.01%;When chemical fertilizer was applied,earthworm activity could significantly increase the content of total carbon of Wuhan and Daye by 9.67% and 14.23% respectively.The species composition,community structure and potential functions of soil bacteria,fungi and protist under different treatments were studied and analyzed by high-throughput sequencing.The results show that although earthworm activity has no significant impact on the dominant microbiomes of soil in the bulk soil,it can change the community structure of soil bacteria,fungi and protist,and the soil bacterial community is more sensitive to earthworm activity.Through the functional prediction of differentially ASV changed by earthworm activities,it is found that when organic fertilizer is applied,earthworm activities can significantly increase the abundance of microorganisms participating in carbon cycle and nitrogen cycle in Wuhan,microorganisms participating in carbon cycle in Daye and consumers.Soil total carbon,total nitrogen,p H and water content comprehensively affect the community structure of soil microorganisms in bulk soil.When applying chemical fertilizer,earthworm activity can significantly increase the abundance of microorganisms participating in carbon cycle,saprotroph and arbuscular mycorrhizal fungi in Daye.Soil moisture content is the main environmental factor affecting soil microbial community in bulk soil.4.The effects of earthworm activities on maize root exudates and rhizosphere microbial composition were related to the type of fertilizationThe species composition,community structure and potential functions of bacteria,fungi and protist in maize rhizosphere under different treatments were studied and analyzed by high-throughput sequencing.Earthworm activity has a significant impact on the community structure of bacteria,fungi and protist in maize rhizosphere,and can significantly increase the abundance of microorganisms participating in carbon cycle,saprotroph and plant pathogens in maize rhizosphere.Under the application of different kinds of fertilizers,earthworm activities led to a significant decrease in the abundance of microorganisms participating in nitrogen cycle in the rhizosphere of maize in Wuhan,and a significant increase in the abundance of microorganisms participating in nitrogen cycle and arbuscular mycorrhizal fungi in the rhizosphere of maize plants in Daye.42 maize root exudates were analyzed and identified.Earthworm activities can promote the secretion of maize root exudates under the application of different kinds of fertilizers.Mantel test found that under the condition of applying organic fertilizer and chemical fertilizer,the main factors affecting the microbial community structure in maize rhizosphere were phenolic and organic acid respectively.5.Soil microorganisms mediated the effects of Earthworm Activities on maize plant growthThe effects of earthworm and fertilizer on maize growth were evaluated by indoor greenhouse experiment when maize planted in non-sterilized soil and sterilized soil.The results of two-way ANOVA showed that earthworm activity significantly affected the SPAD,stem diameter and shoot biomass of maize when maize was planted in non-sterilized soil;When planting maize in sterilized soil,it was found that earthworm activity only had a significant effect on the plant height of maize,and the promoting effect on other growth indexes of maize plant was weakened.The results showed that the effect of earthworm activity on maize plant growth was mediated by soil microorganisms.In conclusion,earthworm activity can significantly affect soil physical and chemical properties,microbial composition and function,and further improve plant yield,which is affected by fertilization types.The results provide an theoretical basis for exploring the effect of earthworm activities on soil microorganisms and further the ecological mechanism of regulating plant. |
PDF Full Text Request