典型水稻土氧化亚氮排放能力与反硝化微生物群落结构和活性的耦合机制

Paddy soil is one of the important emission resources of nitrous oxide. The obvious differences in the ability of nitrous oxide emission in various paddy soil ecosystems were observed, whereas its microbial mechanism is unclear. To illuminate this hypothesis, the long-term original paddy soil pillar observation experiment in Taoyuan Agro-ecosystem Research Station, which was constituted with five kinds of different exogenous paddy soil pillars and three kinds of different soil parent materials, was utilized in this project. Using the molecular biological technology, such as real-time quantitative PCR, Geochip and Illumina sequencing, the inner link between the N2O emission and the physical and chemical properties in these paddy soils were investigated. The change in structure of denitrifying communities in different seasons and years and its relationship with N2O emissions were observed, and the coupling mechanism among the N2O production, consumption and emission, and the abundance and diversity of functional expression and the activities of the key enzymes of the denitrifying communities were also detected. These results will reveal the microbial mechanism and its core difference in the ability of N2O production, consumption and emission in regional representative paddy soils. The results will provide the important theoretical basis in efficient nitrogen utilization and management in paddy soils.

稻田是重要的N2O排放源，不同稻田生态系统N2O排放能力存在明显差异，但产生差异的机制和微生物作用机理尚不明确。本研究将依托我国南方不同母质发育原状水稻土置土试验，运用实时定量PCR、基因芯片和Illumina 测序等分子生物学技术，研究不同水稻土N2O排放特征与土壤物理化学性质的内在联系，置土后不同季节和年份土壤反硝化微生物的群落结构变化规律及其与N2O排放的关系，土壤反硝化微生物在N2O排放关键过程中表达丰度和多样性、关键酶活性及其与N2O产生、消纳和排放的耦合机理。系统揭示具有区域代表性稻田土壤N2O产生、消纳和排放能力的微生物作用机制与核心差别。研究结果对我国南方主要水稻土氮肥高效利用与管理提供重要理论依据。

稻田是重要的N2O排放源，不同稻田生态系统N2O排放能力存在明显差异，但产生差异的机制和微生物作用机理尚不明确。本研究在全国四个气候带采集砖红壤、第四纪红壤、河流冲积物和黑土四种典型母质发育水稻土，利用Illumina 测序等分子生物学技术，系统分析了土壤细菌群落、nirK/nirS、nosZ-I/nosZ-II反硝化功能种群的分布特征及核心驱动因子，明确了土壤母质决定了上述微生物群落结构的差异性，pH、环境温度等是核心驱动因子。同时，依托我国南方不同母质发育原状水稻土异地置土试验，运用Illumina 测序技术，探明了不同母质发育水稻土在置于同一田块后细菌和真菌群落结构随年份（2010-2016年）逐渐趋同；明确了在早稻生长时期砖红壤发育水稻土N2O排放通量相对最高，第四纪红壤母质发育水稻土次之，河流冲积物母质发育水稻土相对最低，nirK、nirS和nosZ功能种群应答迅速且显著受DOC和NO3-等影响因子驱动。在淹水期土壤N2O排放能力表现为砖红壤﹥第四纪红壤﹥河流冲积物，而在落干中后期土壤N2O排放能力表现为第四纪红壤﹥砖红壤﹥河流冲积物，不同母质水稻土narG反硝化功能种群在淹水落干过程应答灵敏，土壤水分、NH4+-N、NO3--N等是N2O排放的关键驱动因子。N2O的消纳能力表现为砖红壤＞河流冲积物＞第四纪红壤，0~5 cm土层淹水土柱对N2O的消纳能力更强，外源N2O添加显著改变各母质水稻土nosZ-I种群结构，但对nosZ-II种群结构影响相对较小。研究结果可为我国南方主要水稻土氮肥高效利用和N2O减排提供重要理论依据。