丛枝菌根真菌(AMF)增加植物从土壤中获得氮(N)的能力,因此会影响一氧化二氮(N2O)的排放,一种长寿命的强效温室气体。然而,AMF对N2O排放影响的潜在机制仍然知之甚少,特别是在具有不同形式的氮肥投入的农业生态系统中。利用野外的中观实验,我们使用15N同位素示踪剂研究了AMF对N2O排放的影响,通过对氨和硝酸盐肥料输入下玉米根系性状和反硝化微生物的影响。在这里,我们表明,单独的AMF或玉米根和AMF的存在增加了玉米生物量和它们的15N吸收,根长,根表面积,和根卷,但导致两种N输入形式下N2O排放量的减少。随机森林模型表明,根长和表面积是N2O排放的最重要预测因素。此外,AMF的存在通过增加氨输入的nirS-缓生根瘤菌和Rubrivivax的相对丰度来降低(nirKnirS)/nosZ比率,但是减少nosZ-偶氮螺旋体,两种肥料输入下的铜和红假单胞菌。Further,N2O排放与NosZ型无螺螺旋菌呈显著正相关,铜和红假单胞菌,但与nirS型缓生根瘤菌和红藻呈负相关。这些结果表明,AMF通过增加根长来探索N养分并改变反硝化氮的群落组成,从而减少了N2O的排放。表明有效管理与根际微生物组相互作用的氮肥形式可能有助于减轻未来氮素输入情景下的N2O排放。
Arbuscular mycorrhizal fungi (AMF) increase the ability of plants to obtain nitrogen (N) from the soil, and thus can affect emissions of nitrous oxide (N2O), a long-lived potent greenhouse gas. However, the mechanisms underlying the effects of AMF on N2O emissions are still poorly understood, particularly in agroecosystems with different forms of N fertilizer inputs. Utilizing a mesocosm experiment in field, we examined the effects of AMF on N2O emissions via their influence on maize root traits and denitrifying microorganisms under ammonia and nitrate fertilizer input using 15N isotope tracer. Here we show that the presence of AMF alone or both maize roots and AMF increased maize biomass and their 15N uptake, root length, root surface area, and root volume, but led to a reduction in N2O emissions under both N input forms. Random forest model showed that root length and surface area were the most important predictors of N2O emissions. Additionally, the presence of AMF reduced the (nirK + nirS)/nosZ ratio by increasing the relative abundance of nirS-Bradyrhizobium and Rubrivivax with ammonia input, but reducing nosZ-Azospirillum, Cupriavidus and Rhodopseudomonas under both fertilizer input. Further, N2O emissions were significantly and positively correlated with the nosZ-type Azospirillum, Cupriavidus and Rhodopseudomonas, but negatively correlated with the nirS-type Bradyrhizobium and Rubrivivax. These results indicate that AMF reduce N2O emissions by increasing root length to explore N nutrients and altering the community composition of denitrifiers, suggesting that effective management of N fertilizer forms interacting with the rhizosphere microbiome may help mitigate N2O emissions under future N input scenarios.