State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, East Beijing Road No. 71, Nanjing 210008, China; University of Chinese Academy of Sciences, Yuquan Road No. 19A, Beijing 100049, China.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, East Beijing Road No. 71, Nanjing 210008, China.
Sci Total Environ. 2019 Feb 1;649:686-694. doi: 10.1016/j.scitotenv.2018.08.318. Epub 2018 Aug 24.
Molybdenum (Mo) deficiency in the farmland of China may limit biological nitrogen fixation (BNF), however, the impact of Mo application on BNF capacities and diazotrophic communities in rice-soil systems is unclear. In this experiment, treatments in a 6.7 atom% N-labelling field-based growth chamber for 74 days and treatments in a 99 atom% N-labelling microcosm experiment for 40 days combined with 16S rRNA gene sequencing and DNA-stable isotope probing (SIP) were used to investigate the impacts of Mo application on BNF and diazotrophic communities. Our results showed that under the condition that no nitrogen (N) fertilizer was applied, Mo application (500 g sodium molybdate ha) significantly increased N fixation in a rice-Inceptisol system, from 22.3 to 53.1 kg N ha. Mo application significantly increased the number of nifH gene copies and the relative abundance of cyanobacteria in both growth chamber and microcosm experiments. Among cyanobacteria, the relative abundances of the most abundant genera Leptolyngbya and Microcoleus were significantly increased by Mo application. N-DNA-SIP further demonstrated that Leptolyngbya and Microcoleus incorporated N Mo application greatly increased BNF in Mo-deficient paddy field (≤0.068 mg kg) and stimulated the growth of cyanobacteria. These results indicated that Mo application in Mo-deficient paddy field could be a useful measure to increase soil N input under no N fertilization.
中国农田缺钼可能会限制生物固氮（BNF），然而，钼施用量对水稻-土壤系统中 BNF 能力和固氮微生物群落的影响尚不清楚。本研究通过田间 6.7%原子丰度氮标记生长箱 74 天和 99%原子丰度氮标记微宇宙实验 40 天的联合处理，结合 16S rRNA 基因测序和 DNA 稳定同位素探针（SIP）技术，研究了钼施用量对生物固氮和固氮微生物群落的影响。结果表明，在不施氮肥的情况下，钼施用量（500g 钼酸钠/公顷）显著增加了水稻-潮土系统的固氮量，从 22.3 增至 53.1kgN/公顷。钼施用量显著增加了生长箱和微宇宙实验中 nifH 基因拷贝数和蓝细菌的相对丰度。在蓝细菌中，Leptolyngbya 和 Microcoleus 的相对丰度因钼施用量的增加而显著增加。N-DNA-SIP 进一步表明，Leptolyngbya 和 Microcoleus 大量掺入 Mo 应用极大地增加了 Mo 缺乏的稻田（≤0.068mg/kg）的生物固氮，并刺激了蓝细菌的生长。这些结果表明，在 Mo 缺乏的稻田中施用钼可以作为一种在不施氮肥的情况下增加土壤氮输入的有效措施。
