孙鹏洲, 罗珠珠, 李玲玲, 牛伊宁, 王晓菲, 田建霞, 刘家鹤. 黄土高原紫花苜蓿种植对土壤反硝化细菌群落的影响[J]. 中国生态农业学报 (中英文), 2023, 31(1): 67−78. DOI: 10.12357/cjea.20220250
引用本文: 孙鹏洲, 罗珠珠, 李玲玲, 牛伊宁, 王晓菲, 田建霞, 刘家鹤. 黄土高原紫花苜蓿种植对土壤反硝化细菌群落的影响[J]. 中国生态农业学报 (中英文), 2023, 31(1): 67−78. DOI: 10.12357/cjea.20220250
SUN P Z, LUO Z Z, LI L L, NIU Y N, WANG X F, TIAN J X, LIU J H. Effects of Medicago sativa cultivation on soil denitrifying bacterial community in the Loess Plateau[J]. Chinese Journal of Eco-Agriculture, 2023, 31(1): 67−78. DOI: 10.12357/cjea.20220250
Citation: SUN P Z, LUO Z Z, LI L L, NIU Y N, WANG X F, TIAN J X, LIU J H. Effects of Medicago sativa cultivation on soil denitrifying bacterial community in the Loess Plateau[J]. Chinese Journal of Eco-Agriculture, 2023, 31(1): 67−78. DOI: 10.12357/cjea.20220250

黄土高原紫花苜蓿种植对土壤反硝化细菌群落的影响

Effects of Medicago sativa cultivation on soil denitrifying bacterial community in the Loess Plateau

  • 摘要: 研究依托布设于黄土高原的长期定位试验, 以紫花苜蓿(Medicago sativa)不同种植年限(2年、9年和18年)土壤为研究对象, 玉米(Zea mays)地为对照, 基于高通量测序技术和荧光定量PCR技术, 结合冗余分析和分子生态网络构建, 通过微生物标志物(nirKnirS)对黄绵土区玉米农田和长期种植紫花苜蓿土壤反硝化细菌群落结构和多样性展开研究。结果表明, 黄绵土区nirK基因丰度明显高于nirS基因丰度, 具有nirKnirS基因的反硝化细菌主要隶属于变形菌门(Proteobacteria)。nirK型反硝化细菌已分类优势属为副球菌属(Paracoccus, 1.10%~39.94%)、无色杆菌属(Achromobacter, 0.07%~12.50%)和中华根瘤菌属(Sinorhizobium, 0.50%~7.60%), 且紫花苜蓿地副球菌属相对丰度显著高于玉米农田(P<0.05), 随紫花苜蓿种植年限延长相对丰度逐渐增加; 无色杆菌属相对丰度表现为紫花苜蓿地显著低于玉米农田(P<0.05), 丰度随苜蓿种植年限的延长逐渐降低; nirS型反硝化细菌优势属为罗河杆菌属(Rhodanobacter, 1.42%~5.20%)。相关性分析表明, nirK反硝化基因丰度变化对土壤环境因子无明显响应, 而nirS反硝化基因丰度与土壤有机碳、全氮和微生物量碳含量呈显著正相关, 与土壤水分和有效磷含量呈显著负相关。冗余分析结果表明, 土壤水分(P=0.002)和有机碳(P=0.020)是nirK型反硝化细菌群落组成变化的主导因子, 土壤有效磷(P=0.006)是nirS型反硝化细菌群落结构产生变化的主导因子。分子生态网络分析表明, 黄绵土区nirK型和nirS型反硝化细菌的群落之间均以协同合作关系为主。长期种植苜蓿显著影响土壤中反硝化细菌的群落组成, 研究结果可为深入探索半干旱区土壤反硝化过程中的微生物机制提供重要科学依据。

     

    Abstract: Microorganisms with nitrite reductase genes can reduce nitrite to nitric oxide (NO), which is an important influence in the biological nitrogen cycle. A field study was conducted to investigate soil denitrifying bacteria (nirK- and nirS-type) communities and diversity in a farmland (Zea mays field) and Medicago sativa land established based on different times (2, 9, and 18 years, respectively expressed as L2019, L2012 and L2003). Illumina MiSeq high-throughput sequencing and real-time fluorescent quantitative PCR technology were used to investigate the structure and diversity of denitrifying bacterial communities under four treatments (Farmland, L2003, L2012 and L2019). Redundancy analysis and molecular ecological network analysis were used to evaluate the relationship between soil physical and chemical properties and denitrifying bacterial community. The results indicated that the abundance of nirK gene was significantly higher than that of nirS gene. The abundance of nirK gene varied from 4.91×107 to 6.33×107 copies∙g−1, whereas the abundance of nirS gene varied from 1.02×107 to 1.86×107 copies∙g−1. The years of M. sativa cultivation did not affect the diversity of nirK- and nirS-type denitrifying bacteria. Proteobacteria had the highest abundance in the denitrifying bacterial community. The dominant genera of the nirK-type denitrifying bacteria were Paracoccus (1.10%–39.94%), Achromobacter (0.07%–12.50%), and Sinorhizobium (0.50%–7.60%). The relative abundance of Paracoccus in M. sativa soil was significantly higher than that in maize soil (P<0.05), and the relative abundance gradually increased with increasing age of M. sativa stands. The relative abundance of Achromobacter in M. sativa soil was significantly lower than that in maize soil (P<0.05), and the abundance decreased gradually with increasing age of the M. sativa stand. The dominant genus of nirS-type denitrifying bacteria was Rhodobacter (1.42%–5.20%). There was no significant difference in Rhodobacter abundance between the maize fields and M. sativa fields. Correlation analysis showed that the abundance of nirK-type denitrifying bacteria had no significant response to soil environmental factors, but the abundance of nirS-type denitrifying bacteria had a significant positive correlation with soil organic carbon (r=0.762), total nitrogen (r=0.776), and microbial biomass carbon (r=0.622) and a significant negative correlation with soil water (r=–0.678) and available phosphorus (r=–0.628). RDA analysis indicated that soil water (P=0.002) and organic carbon (P=0.020) were the main environmental factors affecting the community structure of nirK-type denitrifying bacteria, and soil available phosphorus (P=0.006) was the main environmental factor affecting the community structure of nirS-type denitrifying bacteria. The proportion of positively correlated edges in the nirK-type denitrifying bacterial ecological network was 98.37%, and the proportion of negatively correlated edges was 1.63%; however, all edges in the nirS-type denitrifying bacterial ecological network were positively correlated. This indicated that the relationship between bacterial communities of both types of denitrifying bacterial was mainly synergistic. In summary, long-term planting of M. sativa significantly affected the composition of soil denitrifying bacterial community. Our results provide a scientific basis for further studies on the microbial mechanism of denitrification in the Loess Plateau after years of M. sativa planting.

     

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