Effect Of Different Rotation System On Maize Phosphorus Uptake And Arbuscular Mycorrhizal Fungi In Maize Rhizosphere

The symbiont of arbuscular mycorrhizal and crop is one of the effective system to improving soil P utilization efficiency for crop and help to solve the agricultural phosphorus crisis.However,few studies focused on the relationship between phosphorus requirement of crop and phosphorus uptake of arbuscular mycorrhizal fungi under different rotation system.In this study,two rotation field experiments(corn-soybean,corn-soybean-hay)were conducted at Lishu County.In-site collection of hyphae was used to study the relationship between maize phosphorus requirement and phosphorus uptake by arbuscular mycorrhizal fungi under different rotation system.The collection of hyphae,which made by PVC pipes were inserted around maize roots,and phosphorus depletion and hyphae length density of soil in the PVC compartment were determined.Results and conclusions are as follows:1.Under two rotation systems,maize root colonization and hyphal length density increased with the increasing of shoot phosphorus uptake.These results indicated that rotation system enhanced the P utilization efficiency by AM fungi.2.Compare with the continuous corn cropping system,extraradical hyphae of AM fungi increased significantly under rotation system.The result suggested that P uptake of maize was more dependent on AM fungi in the rotation systems.3.Under two rotation systems,the increment of extraradical hyphae of AM fungi and soil P depletion had a significant correlation(y =-1.934 x + 13.05,r=0.92** in corn-soybean system and y =-1.694 x + 11.75,r = 0.83**in corn-soybean-hay system),but not in continuous corn cropping system.4.Under two rotation systems,the soil P depletion in the topsoil(0-20 cm,20-40cm)was significantly higher than those in deep soil layer(40-60 cm,60-80cm).However,this phenomenon was not found under continuous corn cropping system.5.In-situ,the density of AM hyphae under continuous corn cropping system was higher than that under two rotation systems,which demonstrated that AM fungi in deep soil layer had great contribution to shoot P uptake in continuous corn croppingsystem.