Effects of Reduced ChemicalFertilizer Applications on Fungal Community and Functional Groups in Tea PlantationSoil

Characteristics of fungalcommunity and functional groups in the soil at tea plantations in Wuyishan Cityunder various treatments designed to reduce the use of chemical fertilizers werestudied. Illumina high-throughput sequencing and FUNGuild were employed todetermine the fungal community structure and functional group composition. Thefertilization treatments included applications of non-fertilizer (CK),conventional fertilization (CF), organic fertilizer replacement (OF, with a50.7% reduction on chemical fertilizer), slow release fertilizers (SRF, with a34.4% reduction on chemical fertilizer), and biochar-based formula fertilizer(BF, with a 30.3% reduction on chemical fertilizer). At phylum level,Ascomycota and Basidiomycota accounting for 42.24-48.79% and 21.65-36.11%of total, respectively, were the dominant fungi inthe community. Compared to CF, OF and BF produced significantly higher relativeabundance on Mortierellomycota (P<0.05), and OF significantly loweron Basidiomycota (P<0.05). There were nosignificant differences on other phyla and classes among the soils under the 5treatments. At class level, the relative abundance of Microbotryomycetes underOF was significantly lower than that under CF, but the proportion ofAgaricomycetes significantly higher (P<0.05). The relative abundanceof Mortierellomycetes only was higher under BF than under CF. The diversityindices including Sobs and Shannon were all significantly increased by OF overCF. Saptrotroph was identified as the dominant trophic group in the soils at 37.74-61.56%of total. Compared to CF, OF significantly reduced the proportion of pathotrophgroup by 37.72% due to the addition of organic matters. The increase by 42.27%on the proportion of saprotroph fungi (i.e., mainlythe endophyte-litter saprotroph-soil saprotroph-undefined saprotrophs,ectomycorrhizal-fungal parasites, and fungal parasites) materially alleviatedthe risk of disease spreading at the plantations. A redundancyanalysis attributed organic matters and available potassium in soil to bethe major factors that affected the fungal community structure and functional groups.It appeared that the alpha diversity and abundance index of soil fungi slightlydeclined by chemical fertilization, on the other hand, the incorporation oforganic fertilizer would help maintain a healthy ecosystem in the soil at teaplantations with the increased fungal diversity and proportion of saprotrophs.