摘要:生物固氮是马尾松林地土壤氮素的重要来源，固氮微生物群落组成和数量的变化对土壤氮素供应和地力维持起重要作用。采用池栽试验，应用荧光定量PCR（聚合酶链式反应，Polymerase Chain Reaction）技术，借助Illumina Miseq高通量测序平台，以nifH基因为标靶，研究四类母岩（变余砂岩、长石石英砂岩、石英砂岩和玄武岩）发育马尾松土壤固氮菌群落结构和丰度的差异及其与土壤化学性质之间的关系。结果表明：（1）玄武岩土壤的有机碳、全氮、碱解氮、微生物量氮、马尾松株高和地径均显著高于其他母岩（P < 0.05）。（2）四类母岩土壤nifH基因丰度差异显著，玄武岩土壤nifH基因丰度分别是变余砂岩、石英砂岩和长石石英砂岩的3.75倍、7.89倍和4.41倍。（3）四类母岩土壤固氮菌群落α多样性指数（丰富度和多样性）差异显著，且玄武岩显著高于其他母岩。四类母岩发育土壤共获得有效序列159231条，分属于6个门、14个纲、41个目、69个科和122个属。门水平上，变形菌门和蓝藻门为主要优势类群。属水平上，慢生根瘤菌属、眉藻属、根瘤菌属和固氮螺菌属为主要优势属。玄武岩土壤变形菌门、慢生根瘤菌属、根瘤菌属和固氮螺菌属相对丰度显著高于其他母岩。层次聚类和非度量多维尺度（NMDS）分析结果表明，石英砂岩和长石石英砂岩土壤固氮菌群落结构相似，玄武岩与其他母岩固氮菌群落结构差异较大。（4）土壤有机碳、全氮、碱解氮和微生物量氮是固氮菌丰度、α多样性及群落结构的主要影响因子。综上，玄武岩土壤肥力高，提高了土壤固氮菌数量和群落多样性，有利于马尾松生长。研究从微生物学角度为马尾松适地造林和氮素调控提供了科学依据。



Abstract:Biological nitrogen fixation is the major source of nitrogen in Pinus massoniana areas, and the nitrogen supply and soil fertility maintenance can be largely affected by the composition and quantity of the nitrogen-fixing bacterial community. In this study, pool cultivation experiments were conducted to analyze the relationship between the soil chemical behavior and structure and abundance of the nitrogen-fixing bacterial community in Pinus massoniana soil developed from different parent rocks (blastopsammite, quartzose sandstone, feldspathic quartz sandstone, and basalt). The fluorogenic quantitative real-time PCR technique was adopted in the experiments using the high-throughput sequencing platform Illumina Miseq to target the nifH gene. The results showed that: (1) the Basalt had higher amounts of organic carbon, total nitrogen, alkaline nitrogen, and microbial biomass nitrogen with larger plant height and diameter compared with other types of parent rocks(P < 0.05). (2) The abundances of the nifH gene varied significantly for the four types of parent rocks; more specifically, the nifH gene abundances of basalt were 3.75, 7.89, and 4.41 times higher than those of blastopsammite, quartzose sandstone, and feldspathic quartz sandstone, respectively. (3) The diversity index α (abundance and diversity) of the four types of parent rocks was significantly different, and basalt showed a considerably higher α than that of other parent rocks. In total, 159,231 valid sequences, which belong to 6 phyla, 14 classes, 69 orders, and 122 genera, were obtained from the soil of the four parent rocks. Proteobacteria and Cyanobacteria were the dominant phyla, whereas Bradyrhizobium, Calothrix, Rhizobium, and Azospirillum were the dominant genera. Compared with other parent rocks, basalt had higher abundances of Proteobacteria, Calothrix, Rhizobium, and Azospirillum. The results from hierarchical clustering and non-metric multidimensional scaling (NMDS) showed that for the nitrogen-fixing bacterial community, quartzose sandstone and feldspathic quartz sandstone shared a similar structure, whereas basalt had a different structure compared with the other types of parent rocks. (4) The amounts of organic carbon, total nitrogen, alkaline nitrogen, and microbial biomass nitrogen were the main factors for the abundance of nitrogen-fixing bacteria, the diversity of α, and the structure of the bacterial community. In general, basalt soil had a high fertility, increased the amount of nitrogen-fixing bacteria, and enhanced the diversity of the bacterial community, thereby facilitating the growth of Pinus massoniana. Our study provides a scientific basis for selecting the appropriate growth environment and nitrogen adjustment for Pinus massoniana from a microbiological point of view.





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