高寒草原优良牧草根际土壤细菌数量及分布特征研究

Study on Quantities and Distribution Characteristics of Bacteria in Pasture Rhizosphere Soil of Alpine Prairie

为了研究高寒草原植物根际土壤微生物的分布变化特征,本研究选择藏北高原西藏阿里地区四种草地优良牧草披碱草(Elymus dahuricus)、燕麦(Avena sterilis Linn)、紫花苜蓿(Medicago sativa)和草地早熟禾(Poa pretensis)。采集植物根际土壤样品,采用培养皿法研究了植物根际四个区域细菌的数量,同时测定了土壤的理化性质,并分析了根际土壤细菌的分布特征及与土壤理化性质的相关关系。结果表明,四种植物根际土壤养分含量较低,土壤总体有效养分的供给能力较弱,根际分布细菌的数量偏低,不同植物根际土壤养分含量及细菌的数量差异显著,植物根际土壤的理化性质和养分含量与细菌的数量间存在一定的相关性。其中,土沙比与细菌数量间存在极显著性负相关关系(P<0.01),土壤的pH值与细菌数量间存在显著性负相关关系(P<0.05),而土壤的有机质、速效氮、速效磷、速效钾含量与细菌数量间存在极显著性正相关关系(P<0.01),土壤全氮、全磷、全钾、有效锰与细菌数量间存在显著性正相关关系(P<0.05),土壤性质、气候环境、植被环境综合因素对植物根际土壤微生物的影响有待进一步研究。

To explore the distribution characteristics of plant rhizosphere soil microorganisms in the Alpine prairie,in this study,four grassland species,Elymus dahuricus,Avena sterilis Linn,Medicago sativa,and Poa pretensis,were selected from four grassland species in the Ali region of the northern Tibet Plateau.Plant rhizosphere soil samples were collected,the petri dish method was used to study the number of bacteria in four areas of the plant rhizosphere,physical and chemical properties of soil were also determined,and the correlation between distribution characteristics of rhizosphere soil bacteria and soil physical and chemical properties were analyzed.The results showed that nutrient content in rhizosphere soil of four plants is low,supply capacities of soil overall effective nutrients were weaker,numbers of bacteria in rhizosphere were lower,there were significant differences between nutrient content and bacteria in rhizosphere soil of different plants,there was a certain correlation between the physical and chemical properties and nutrient content of the rhizosphere soil and the numbers of bacteria.Particularly,there was a very significant negative correlation between the soil-sand ratio and the numbers of bacteria(P<0.01),there were a significant negative correlation between soil pH and numbers of bacterial(P<0.05),however,There was a very significant positive correlation between soil organic matter,available nitrogen,available phosphorus,available potassium and the number of bacteria(P<0.01),There was a significant positive correlation between soil total nitrogen,total phosphorus,total potassium,available manganese and the number of bacteria(P<0.05),the effects of comprehensive factors of soil properties,climatic environment and vegetation environment on plant rhizosphere soil microorganisms need to be further study.