Wang Cong, Wu Ne, Hou Hai-Jun, Tang Ya-Fang, Shen Jian-Lin, Qin Hong-Ling
Public Service Technology Center, Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Huan Jing Ke Xue. 2016 Nov 8;37(11):4372-4379. doi: 10.13227/j.hjkx.201604220.
Fertilizer applications have important effects on soil microbial abundance and community structure. In this study, total soil microbial DNA and RNA were directly extracted from paddy soils of N0 (control treatment, no nitrogen fertilizer), NPK (balanced fertilization), NPK+LS (balanced fertilization with additional 3.0 t·hm rice straw incorporation) and NPK+HS (balanced fertilization with additional 6.0 t·hm rice straw incorporation) treatments in a long-term fertilization experiment of double rice cropping system in Changsha County, Hunan Province. Soil bacteria community structures were evaluated by analyzing the 16S rRNA gene fragments at DNA and cDNA levels with Terminal Restriction Fragment Length Polymorphism (T-RFLP) and quantitative PCR techniques. Balancing fertilization with chemical fertilizers and rice straw incorporation significantly changed the composition of bulk (DNA-based) and potentially active (mRNA-based) soil bacterial community as shown in T-RFLP profiles, and also reduced the bulk soil microbial diversity, but not the potentially active ones, as compared with the control treatment. The DNA-based abundance of 16S rRNA gene was on average 377 times as many as the m-RNA based population size. Compared to N0,balanced fertilization with rice straw incorporation (NPK+LS and NPK+HS) increased the bulk and active copy numbers of 16S rRNA gene, but not for balanced fertilization (NPK). The abundance and microbial community structure were not significantly different between the NPK+LS and NPK+HS treatments. Redundancy analysis (RDA) showed that soil ammonium was the key environmental factor determining the bulk and active soil microbial community structure among the treatments. In conclusion, the effect of fertilization on soil microbial abundance and community structure could be indicated at both DNA and cDNA levels; the cDNA information could better reflect the adaptability of bacterial community to the environmental stress.
施肥对土壤微生物丰度和群落结构具有重要影响。本研究从湖南省长沙县双季稻种植系统长期施肥试验中的N0（对照处理，不施氮肥）、NPK（平衡施肥）、NPK+LS（平衡施肥并额外添加3.0 t·hm稻草还田）和NPK+HS（平衡施肥并额外添加6.0 t·hm稻草还田）处理的稻田土壤中直接提取了总土壤微生物DNA和RNA。通过采用末端限制性片段长度多态性（T-RFLP）和定量PCR技术，在DNA和cDNA水平分析16S rRNA基因片段，对土壤细菌群落结构进行了评估。如T-RFLP图谱所示，化肥与稻草还田的平衡施肥显著改变了大量（基于DNA）和潜在活性（基于mRNA）土壤细菌群落的组成，与对照处理相比，还降低了大量土壤微生物多样性，但未降低潜在活性土壤微生物多样性。基于DNA的16S rRNA基因丰度平均是基于mRNA的群体大小的377倍。与N0相比，稻草还田的平衡施肥（NPK+LS和NPK+HS）增加了16S rRNA基因的大量和活性拷贝数，但平衡施肥（NPK）则未增加。NPK+LS和NPK+HS处理之间的丰度和微生物群落结构没有显著差异。冗余分析（RDA）表明，土壤铵是各处理中决定大量和活性土壤微生物群落结构的关键环境因素。总之，施肥对土壤微生物丰度和群落结构的影响可在DNA和cDNA水平上体现；cDNA信息能更好地反映细菌群落对环境胁迫的适应性。
