Elevated N2O emission by the rice roots: based on the abundances of narG and bacterial amoA genes
2017
Zhang, Zhenxing | Zhang, Wenzhao | Yang, Huicui | Sheng, Rong | Wei, Wenxue | Qin, Hongling
Rice fields are an important source of nitrous oxide (N₂O), where rice plants could act as a key factor controlling N₂O fluxes during the flooding-drying process; however, the microbial driving mechanisms are unclear. In this study, specially designed equipment was used to grow rice plants and collect emitted N₂O from the root-growing zone (zone A), root-free zones (zones B, C, and D) independently, at tillering and booting stages under flooding and drying conditions. Soil samples from the four zones were also taken separately. Nitrifying and denitrifying community abundances were detected using quantitative polymerase chain reaction (qPCR). The N₂O emission increased significantly along with drying, but the N₂O emission capabilities varied among the four zones under drying, while zone B possessed the highest N₂O fluxes that were 2.7~4.5 times higher than those from zones C and D. However, zone A showed N₂O consumption potential. Notably, zone B also harbored the highest numbers of narG-containing denitrifiers and amoA-containing nitrifiers under drying at both tillering and booting stages. This study demonstrates that drying caused significant increase in N₂O emission from rhizosphere soil, in which the higher abundance of AOB would help to produce more nitrate and significantly higher narG-containing microbes would drive more N₂O production and emission.
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