| Arbuscular mycorrhizal fungi (AM) exist widely in agricultural system, which may be associated with the vast majority of crop to be arbuscular mycorrhiza formation. AM can improve nutrient and water absorption of the crops, and can increase crop yield, improve crop resistance to biotic and abiotic factors and soil structure.The paper focued on the effects of agricultural farming practices including tillage,no-tillage,tillage+stubble return and no-tillage+stubble return on the function, infection rate and the biodiversity of AM fungi.The experiment was proceeded in the glasshouse,and experimental soil was derived from the above four kinds of soil.Those soil was divided into two parts,One keeped untreatment (fungi treatment),and the other part was sterilizated (sterilized treatment).Both of fungi treatment and sterilized treatment soils were mixed with steriled sand by the weight of 10:0,4:6 and l:9.Alfafa of Longdong was then sowed in the pots.The results as follows:(1)AM fungi promoted the growth of alfafa(the number of leaves,height,bioma-ss) in the four farming practices with different degrees, especially in the soil of 10:0. But the promotion of growth is limited to the soil of 1:9,which indicate the inoculati-on qulity of AM fungi is important to increase the growth of plant.Function of AM fungi is significantly related with farming practices,the biomass of alfalfa from high to low were:NT>NTS>TS>T.Alfalfa grown in sterilized treatment soil given similar biomass among the four agricultural practices. There is a positive correlation between the inoculation amount and the growth of alfafa, and the biomass ranked from high to low under the same farming practice were:10:0>4:6>1:9.(2)AM fungi promoted plant P absorption under the different farming practices and the P content in fungi treatment soils were significaly lower than that in sterilized treatment soils.The 10:0 soil had higher P content than other two both before and after the harvest and also the plant grown in 10:0 soil had higher P content than that the other two.However plant in the three type soils given the similar trend in P content,the shoot P of alfalfa ranked from high to low were TS>NTS>NT>T;the root P content ranked from high to low were NTS>NT>TS>T. sterilized treatment given the similar P content both in shoots and roots.Plant total P ranked from high to low under the same farming practice were:10:0>4:6>1:9.(3)AM fungi increased the formation of the soil aggregate range from 2 to 0.25mm,and the stubble return mainly influence the soil aggregate of 2mm diameters.(4)Alfalfa had higher AM colonization in 10:0 soil than that in 4:6 and 1:9 soil. AM colonization from high to low was NT>TS>T>NTS in 10:0 soil,while NT>TS>NTS=T in 4:6 soil and the 1:9 soil.Stubble return only increased AM fungi infection under traditional tillage in the 10:0 soil.(5)Total of 12 AM fungi species belongs to 4 genera were isolated in the four farming practices under greenhouse experiment, of which no tillage (NT) given the highest AM fungi diversity including 10 species belong to Diversispora, Glomus, Gigaspora and Sculellospora, while traditional tillage (T) given the lowest AM fungi diversity which includes 3 species belongs to Glomus and Gigaspora.Low temperature in winter decreased AM fungi diversity compared with greenhouse,11 species belongs to 3 genera AM fungi were isolated in the field soil after winter. NT and T had the highest and lowest AM fungi diversity which had 9 species belongs to Glomus,Gigaspora,Scutellospora and 3 species belongs Glomus,Gigaspora respectively.AM fungi diversity ranked from high to low were NT>NTS>TS>T both in the greenhouse and field.Glomus was the dominant specie in the soil of greenhouse experiment and field. |
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