Analysis Of Rhizosphere Effect Of Different Mycorrhizal Tree Species In Typical Black Soil Area

Using Picea koraiensis,Betula platyphylla,and Pinus sylvestris var.Mongolica,Armeniaca sibirica,Acer negundo,Amygdalus triloba,and Viburnum sargenti that growing in the black soil area of northeast China as research material,the difference in root exudation rate and rhizosphere effect between different mycorrhizal tree species were analyzed,and evaluate its effect on soil improvement.The main results were as follow:1.The results showed that therewere significant differences among 7 tree species(p<0.05),and the root exudation rate of ECM(ectomycorrhizal)tree species(P.koraiensis,B.platyphylla.and P.sylvestris var.Mongolica)was significantly higher than that of AM(arbuscular mycorrhizal)tree species(A.triloba,V.sargenti,A.negundo,and A.sibirica)(p<0.05).2.The soil nutrients are significantly affected by the rhizosphere effect of tree species.Relative to bulk soil,the rhizosphere soil pH of V.sargenti,A.sibirica and A.saccharum was increased 0.32-5.79%,and was decreased by 1.91-5.21%in A.triloba,P.koraiensis,B.platyphylla,and P.sylvestris var.Mongolica rhizosphere soil.Rhizosphere effects on soil total organic carbon(TOC),total nitrogen(TN),alkali-hydrolyzed nitrogen(ALN),total phosphorus(TP),and available phosphorus(AP)in the rhizosphere soil of the 7 tree species were greater 23.4-238.6%,8.8-145.2%,5.2-23.3%,5.1-48.8%and 16-183.7%than in bulk soil,respectively.The rhizosphere effects of ECM trees on TOC,TN,and ALN were greater than in the AM trees,and the rhizosphere effects of soil TP and AP in the AM tree species was significantly greater than that of in the ECM tree species.3.Compared with to the bulk soil,the number of bacteria and actinomycetes in the rhizosphere soil of the 7 tree species increased 75.16-337.4%and 15.1%-190.8%.The abundance of fungi in the rhizosphere soil of A.sibirica and A.triloba was decreased by 22.2%and 0.45%,respectively,and was increased 44%-212.1%in the rhizosphere soil of other tree species.The rhizosphere effect on abundance of bacteria and fungi in the ECM trees was greater than that of in the AM trees(p<0.05),while the rhizosphere effect of actinomycetes was not significantly different between the AM and ECM tree species(p>0.05).4.The correlations among root exudation rate,microbial abundance and soil nutrients were significantly different between ECM and AM tree species.Among ECM tree species,the soil TP content was significantly correlated with root exudation rate and abundance of fungi and actinomycetes.And there was no significant between the other factors(p>0.05).In AM tree species,the degree of correlation among the factors is much more complex.In AM tree species,the root exudation rate was significantly positively correlated with abundance of bacteria,fungi and actinomycetes,as well as the content of AP.the root exudation rate was significantly correlated with the TN and TP content.Contents of TOC and AP were significantly correlated with abundance of bacteria,fungi and actinomycetes.The abundance of soil bacteria,fungi and actinomycetes was positively correlated with each other.5.The improvement effects on soil quality from high to low are P.koraiensis,P.sylvestris var.Mongolica,B.platyphylla,V.sargenti,A.saccharum,A.triloba and A.sibirica.The effect of ECM species on soil improvement is higher than that of AM tree species.In summary,there are significant differences between ECM and AM tree species in terms of root exudation rate,microbial quantity and soil quality,but both of the two mycorrhizal tree species can improve soil quality to a certain extent.From a comprehensive point of view,the three ECM tree species of P.koraiensis,P.sylvestris var.Mongolica and B.platyphylla have better soil improvement effects,and are more suitable as soil improvement tree species in the typical black soil area of Northeast China.