Effects of weed management methods on the ecological function of soil fungi in plum orchards and adjacent natural forests

【Objective】To explore impacts of weed management in plum orchards on soil fungal diversity to provide reference for soil health management.【Method】In Ziyun County of Anshun City, Guizhou Province, soil of natural growing grass and planted grass in plum orchards, soil with herbicide in plum orchards, and soil of adjacent natural Quercus aliena secondary forests were selected as research objects. Then soil fungal DNA was extracted from the soils and its ITS genes were amplified and sequenced with high-throughput sequencing to analyze the composition, relative abundance, diversity and ecological function categories of fungal species.【Result】The number of operational taxonomic unit(OTU) of soil in plum orchards and adjacent natural forests under different weed management methods ranged from 420 to 1039. Fungal categories included 14 phyla, 51 classes, 127 orders, 260 families and 492 genera. The number of OTU of soil in natural Q. aliena secondary forests was less than half of that of soil in plum orchards. Basidiomycota and Ascomycota were main fungi in the four treatmentss of soils. Compared with natural forests, Basidiomycota in plum orchards decreased, while Ascomycota increased. And the changing range of soil of planted grass in plum orchards was small, which were 36.79%and 32.85% respectively. Russula in the soil of natural forests occupied absolute advantages, with relative abundance reaching 54.44%. Saitozyma was the first dominant genus in different types of soils in plum orchards, with relative abundance ranging from 14.54% to 38.11%. The advantage of planted grass in plum orchards was obvious. In addition, the relative abundance of Kickxellomycota and Glomeromycota in the soil of planted grass in plum orchards was higher than that of other types. The diversity analysis showed that differences of α diversity among soil in natural forests and other soils in plum orchards were extremely significant(P<0.01, the same below). Under different weed management methods, the differences of Simpson index between planted grass and natural growing grass were extremely significant. According to the analysis of FUNGuild, Ectomycorrhizal was absolutely dominant in the soil of natural forests, while Saprotrophs and unknown fungi were the main fungi in the soil of plum orchards.【Conclusion】Planted grass(Vicia villosa Roth var.) in plum orchards is beneficial for the establishment of dominant genus Saitozyma, Kickxellomycota with low abundance and Glomeromycota communities. There is a few arbuscular mycorrhiza fungi(Glomeromycota) in plum orchards under different weed management methods. The plum orchards also lack dominant beneficial fungi, so more improvement is needed for the application of beneficial fungi in plum trees. The structure of dominant fungi leads to differences in ecological function of fungal communities under different treatments.