Seasonal and Depth-wise variation in Microfungal Population Numbers in Nameri forest soil, Assam, Northeast India

Soil microflora was isolated by serial dilution plate method using different culture media. The highest fungal population was recorded in spring at the topsoil (1–9 cm), and decreased in other seasons with increasing depths. Twenty-one fungal species belonging to 14 genera were recovered from all depths throughout the seasons with the highest population and relative abundance of Aspergillus flavus (8.4%), followed by Penicillium chrysogenum (8.0%) and lowest by Rhizopus oryzae, R. nodosus and Trichophyton sp. (2.8% each). Phycomycetes (80.1%) were dominant in the study site followed by Zygomycetes (14.1%), Ascomycetes (3.7%) and sterile mycelia (2.1%). Soil pH, moisture content, organic C (Corg), total N concentration (Ntot) and available K had positive correlations (p<0.05 and <0.01) with the fungal colony forming unit. Difference in soil depth and seasonal variation have an influence on the microfungal population numbers as well as their species composition in Nameri forest soil.本研究采用系列稀释平板法，结合多种培养基对土壤微生物区系进行分离培养。表层土壤（1~9 cm）的真菌群落数量在春季达到峰值，其余季节的真菌群落数量则随土层深度增加而逐渐降低。本研究在各季节的各土层中共分离得到隶属于14个属的21种真菌，其中黄曲霉（Aspergillus flavus）的群落数量与相对丰度最高，占比达8.4%；其次为产黄青霉（Penicillium chrysogenum），占比8.0%；占比最低的为米根霉（Rhizopus oryzae）、结节根霉（Rhizopus nodosus）和毛癣菌属（Trichophyton sp.），三者占比均为2.8%。研究区域内的真菌类群以藻菌纲（Phycomycetes）占绝对优势，占比达80.1%；其次为接合菌纲（Zygomycetes，14.1%）、子囊菌纲（Ascomycetes，3.7%）和无孢菌丝体（sterile mycelia，2.1%）。土壤pH值、含水量、有机碳（Corg）、总氮浓度（Ntot）以及速效钾含量均与真菌菌落形成单位呈显著正相关（p<0.05及p<0.01）。土层深度差异与季节变化均会影响纳梅里（Nameri）森林土壤中的微真菌群落数量及其物种组成。