丛枝菌根真菌对褐土玉米氮素吸收和土壤N2O排放的影响OA北大核心CHSSCDCSTPCD

The aim of this study was to explore the influences of arbuscular mycorrhizal(AM)fungi on N2O emissions and nitrogen-transforming functional genes in maize-growing cinnamon soil under different nitrogen fertilizer rates,so as to provide the theoretical basis for clarifying the mechanism of AM fungi on N2O emissions in cinnamon soil.Two factorial pot experiments were established as follows:nitrogen fertilizer application rates(NⅠ:105 mg/kg;NⅡ:210 mg/kg)and AM fungi treatments(M0:no AM fungi inoculation;M1:Rhizophagus intraradices;M2:Funneliformis mosseae;M3:Rhizophagus intraradices+Funneliformis mosseae).Soil ammonium nitrogen,nitrate nitrogen,maize total nitrogen content,and soil N2O flux were measured.The abundance of soil nitrification functional genes(amoA-AOA and amoA-AOB)and denitrification functional genes(nirS,nirK and nosZ)were determined by using real-time fluorescence quota PCR.The results showed that all AM fungi treatments significantly reduced soil N2O emission fluxes and emission accumulations.The effect of AM fungi in reducing soil N2O emission accumulation was ranked as follows:M0＞M2＞M1＞M3.Soil N2O emission fluxes and emission accumulation of the same AM fungi treatment were higher at NⅡ input than at NⅠ input.AM fungi colonization of the same AM fungi treatment was lower at NⅡ input than at NⅠ input.Compared with M0 treatment,soil ammonium nitrogen content with M1,M2,and M3 treatments under the conditions of NⅠ input reduced by 24.5%,20.8%,and 45.3%,by 19.7%,14.9%,and 30.2%for nitrate nitrogen content,and increased by 16.3%,35.2%,and 59.6%for aboveground total nitrogen content,respectively.However,under the conditions of NⅡ input,soil ammonium nitrogen content with M1,M2,and M3 treatments reduced by 20.9%,24.8%,and 40.0%,by 36.3%,25.6%,and 45.2%for nitrate nitrogen content,and increased by 33.2%,43.9%,and 95.4%for aboveground total nitrogen content,respectively.Under both nitrogen fertilizer input rates,the AM fungi significantly reduced the abundance of nitrification functional genes(amoA-AOA and amoA-AOB)and increased the abundance of denitrification functional genes(nirS,nirK and nosZ).AM fungi was significantly negatively correlated with the soil N2O emission fluxes.Under the conditions of the present pot experiment,our study concluded that AM fungi could improve nitrogen absorption capacity of maize plants with two nitrogen fertilizer application rates,regulate nitrification and denitrification functional genes abundance and reduce N2O emission.The N2O emission reduction effect of two AM fungi mixed treatment was stronger than the single AM fungi inoculation.