Composition of Archaeal Community in a Paddy Field as Affected by Rice Cultivar and N Fertilizer

Methanogenesis in paddy fields is significantly influenced by environmental and field management factors such as rice cultivar and nitrogenous fertilizer. However, it has been unclear whether such effects are reflected in the structure of methanogenic archaeal populations. In the present study, molecular analyses including cloning and sequencing and terminal restriction fragment length polymorphism (T-RFLP) fingerprinting of archaeal 16S rRNA genes were used to characterize the methanogenic archaeal assemblages and to identify the effect of environmental variables including rice cultivar and N fertilizer on archaeal community compositions in a Chinese paddy field soil. The correlation between methanogenic archaeal composition and environmental variables was explored by correspondence analysis. The results showed that the spatial or niche factor (rice roots versus rhizosphere, surface, and the deeper layer soils) had the greatest influence on the archaeal community composition. There was an obvious enrichment or selection of hydrogenotrophic as opposed to acetoclastic methanogens by rice roots. The archaeal community also changed, though slightly, between the rhizosphere and bulk soils and between the surface soil and the deeper layer soil. However, rice cultivar and N fertilizer appear to have an effect only on methanogens tightly associated with rice roots.