连作与轮作对杨树人工林土壤解磷微生物类群特征及磷代谢的影响

发布时间：2018-08-24 13:03

【摘要】：土壤养分循环障碍是人工林地力衰退的重要成因,土壤微生物群落在土壤养分循环中发挥重要作用。磷是植物重要的矿质营养成分,对植物的生长和发育发挥重要作用。研究土壤解磷微生物类群演变动态,有助于阐明连作和轮作对杨树人工林土壤磷循环影响的微生态机制,为科学经营人工林提供理论依据。本研究基于宏基因组测序技术,分析了杨树人工林Ⅰ代林地和连作Ⅱ代林地的根际土和非根际土、Ⅱ代林地主伐后轮作花生地和轮荒地土壤中解磷微生物类群及磷代谢随不同连作和轮作方式的变化规律。研究结果如下:(1)在杨树人工林不同连作和轮作方式土壤中共检测出5种酚酸物质,分别为对羟基苯甲酸、苯甲酸、阿魏酸、香草醛和肉桂酸,酚酸类物质总量表现为Ⅱ代林Ⅰ代林轮作花生地轮荒地。土壤理化性质在不同土壤样品中变化规律表现不同,pH、有机质和有效钾含量显著差异,全磷、有效磷、有效氮含量无显著性差异。(2)土壤样品中共检测到细菌域微生物类群8个门,分属厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)、拟杆菌门(Bacteroidetes)、绿弯菌门(Chloroflexi)、疣微菌门(Verrucomicrobia)和浮霉菌门(Planctomycetes)。厚壁菌门丰度最高,其次是变形菌门和放线菌门。轮作降低了微生物群落多样性,Ⅱ代林土壤微生物群落多样性低于Ⅰ代林但差异并未达到显著水平。与Ⅰ代林相比,土壤微生物在属分类水平变化明显,Ⅱ代林、轮作花生地和轮荒地土壤中微生物种类减少,微生物群落结构发生改变。功能基因总丰度表现为Ⅰ代林轮荒地Ⅱ代林轮作花生地。人工林连作后,参与复制、重组与修复,翻译、核糖体结构与生物合成功能的基因丰度降低。Ⅱ代林主伐轮作后,总体上功能基因丰度无显著变化。(3)杨树人工林不同连作和轮作方式土壤中共检测出9属解磷微生物。其中:细菌7属,分别为芽孢杆菌属(Bacillus)、假单胞菌属(Pseudomonas)、黄杆菌属(Flavobacterium)、类芽孢杆菌属(Paenibacillus)、慢生根瘤菌属(Bradyrhizobium)、泛生菌属(Pantoea)、沙雷氏菌属(Serratia);放线菌2属,为链霉菌属(Streptomyces)和节杆菌属(Arthrobacter)。芽孢杆菌属和假单胞菌属为优势菌群。泛生菌属、类芽孢杆菌和沙雷氏菌属分别为Ⅰ代林地、Ⅱ代林地和轮荒地独有菌群,但所占比例均低于0.1%。(4)杨树人工林连作、轮作和轮荒后,Ⅰ代林地和Ⅱ代林地解磷微生物占各样地解磷微生物总丰度的22.4%和23.1%,轮作花生地和轮荒地解磷微生物占各样地解磷微生物总丰度的26.8%和27.7%,与连作相比,轮作可以增加解磷微生物的数量。与Ⅰ代林地相比,Ⅱ代林地土壤中各属共有解磷微生物丰度均有不同程度增加。与Ⅱ代林地相比,主伐更新后轮作花生地和轮荒地土壤中芽孢杆菌属和假单胞菌属丰度分别增加19.9%和30.3%、20.4%和71.4%,而节杆菌属、慢生根瘤菌属、链霉菌属丰度则降低,且降幅均在50%以上。(5)杨树人工林根际解磷微生物总丰度显著低于非根际,芽孢杆菌属和假单胞菌属细菌在杨树根际土壤中显著低于非根际土壤,R/S值分别为0.6~0.7:1和0.4~0.7:1,而节杆菌属、慢生根瘤菌属、链霉菌属的丰度显著高于非根际土壤,细菌R/S值为4~7:1,放线菌R/S值为2~6:1。(6)在不同土壤中磷酸酶基因总丰度表现为Ⅰ代林地轮荒地Ⅱ代林地轮作花生地。Ⅱ代林地主伐更新后,轮荒地磷酸酶基因总丰度升高,轮作花生地为各样本中最低。根际与非根际之间,Ⅰ、Ⅱ代林土壤磷酸酶R/S值分别为1.39和1.09,在Ⅱ代林中根际与非根际土壤磷酸酶丰度差异缩小,部分磷酸酶丰度甚至低于非根际土壤。Ⅱ代林根际土壤各磷酸酶丰度低于Ⅰ代林根际土壤。(7)与Ⅰ代林相比,Ⅱ代林土壤中有机磷转化作用强度降低16.63%,人工林连作降低土壤可利用磷的含量。Ⅱ代林主伐后,轮作花生地土壤中有机磷转化作用强度比Ⅱ代林升高32.36%,轮荒地土壤中有机磷转化作用强度比Ⅱ代林升高25.44%。轮作和撂荒可以增加土壤中可利用磷的供应,改善林地生产力。
[Abstract]:The disturbance of soil nutrient cycling is an important cause of soil fertility decline in artificial forests. Soil microbial communities play an important role in soil nutrient cycling. Phosphorus is an important mineral nutrient component of plants and plays an important role in the growth and development of plants. The microecological mechanism of phosphorus cycling in soils of poplar plantations provides a theoretical basis for the scientific management of plantations. Based on the macrogenomic sequencing technique, the rhizosphere and non-rhizosphere soils of the first and second generation plantations of poplar plantations, the phosphorus-solubilizing microbial groups in the soils of peanut and wasteland after the second generation plantations were analyzed. The results were as follows: (1) Five phenolic acids were detected in the soil of Poplar Plantations under different successive cropping and rotation patterns, namely, p-hydroxybenzoic acid, benzoic acid, ferulic acid, vanillin and cinnamic acid. The total phenolic acids were found to be in the second-generation rotation of peanut fields. (2) Eight phyla of bacterial microflora, belonging to Firmicutes, Proteobacteria, Actinomycetes, were detected in soil samples. Actinobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, Verrucomicrobia and Planctomycetes were the most abundant, followed by Proteus and Actinomycetes. Compared with the first-generation forest, the soil microbial species in the second-generation forest, rotation peanut land and rotation wasteland decreased and the microbial community structure changed. After continuous cropping, the abundance of genes involved in replication, recombination and restoration, translation, ribosomal structure and biosynthetic function decreased. There was no significant change in functional gene abundance after the second-generation rotation. (3) Nine genera of phosphorus-solubilizing microorganisms were detected in the soils of Poplar Plantations under different continuous cropping and rotation patterns. Bacillus, Pseudomonas, Flavobacterium, Paenibacillus, Bradyrhizobium, Pantoea, Serratia, Actinomyces, Streptomyces and Arthrobacter, Bacillus and Pseudobacterium (4) After continuous cropping, rotation and rotation, 22.4% and 23.1% of the total phosphorus-solubilizing microorganisms were found in the first and second generation of poplar plantations, respectively. Phosphorus-solubilizing microorganisms accounted for 26.8% and 27.7% of the total phosphorus-solubilizing microbial abundance in both raw and rotated wasteland. Compared with continuous cropping, rotation could increase the number of phosphorus-solubilizing microorganisms. The abundance of Bacillus and Pseudomonas increased by 19.9% and 30.3%, 20.4% and 71.4% respectively, while that of Arthrobacter, Bradyrhizobium and Streptomyces decreased by more than 50%. (5) The total abundance of P-solubilizing microorganisms in rhizosphere of poplar plantation was significantly lower than that of non-rhizosphere, Bacillus and Pseudomonas. The R/S values in poplar rhizosphere soil were 0.6-0.7:1 and 0.4-0.7:1, respectively. The abundance of Streptomyces in Arthrobacter, Bradyrhizobium and Streptomyces was significantly higher than that in non-rhizosphere soil. The R/S values of bacteria were 4-7:1 and the R/S values of actinomycetes were 2-6:1. The total abundance of phosphatase gene in the rotation wasteland was the lowest among the samples. The R/S values of phosphatase in the rhizosphere and non-rhizosphere were 1.39 and 1.09 respectively. The difference of phosphatase abundance between rhizosphere and non-rhizosphere soil in the second generation forest was narrowed, and the abundance of partial phosphatase was very high. Phosphatase abundance in rhizosphere soil of the second-generation forest was lower than that of the first-generation forest. (7) Compared with the first-generation forest, the transformation intensity of organic phosphorus in soil of the second-generation forest was reduced by 16.63%, and the content of available phosphorus in soil was decreased by continuous cropping of plantations. The conversion intensity of organic phosphorus increased by 32.36% in replaced forest and 25.44% in rotated wasteland compared with that in the second generation forest.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714;S792.11

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