Abstract: The community structure of soil nematodes serves as a crucial indicator for the changes in soil environmental conditions and ecosystem functioning. Based on Illumina Miseq sequencing technology, we examined the effects of different fertilization modes on the community structure and diversity of soil nematodes in newly-built honey peach orchards in Chengdu Plain and explored the primary influencing factors. The treatments were conventional management (HCK), the incorporation of rapeseed meal cake fertilizer (HB), planting a green manure crop (Vicia villosa var. glabrescens, HG), application of selenium fertilizer (HX), a combination of green manure and rapeseed meal cake fertilizer (HGB), and a blend of selenium and rapeseed meal cake fertilizers (HXB). The results showed that soil nematode species in the peach orchards encompassed 17 classes, 92 families, and 133 genera, with Colpoda and Acrobeloides being the dominant nematode groups (the average relative abundance was 38.16% and 20.77%, respectively). The selenium fertilizer treatment yielded the highest relative abundance of these dominant groups, whereas green manure treatment exhibited the lowest. The ACE richness index of soil nematodes did not differ among different fertilization modes. Shannon diversity index was significantly higher in green manure treatment (HG) than other treatments, particularly in the green manure + rapeseed meal cake fertilizer treatment (HGB). Additionally, rapeseed meal cake fertilizer (HG), selenium fertilizer (HX), and selenium fertilizer + rapeseed meal cake fertilizer (HXB) treatments exhibited significantly higher Shannon diversity indices than the green manure + rapeseed meal cake fertilizer treatment (HGB). Cluster analysis categorized the soil nematode communities under the six fertilization schemes into two groups: one group comprising rapeseed meal cake fertilizer (HB), green manure (HG), and green manure + rapeseed meal cake fertilizer (HGB), and the other group including other three fertilization schemes. Soil pH and nitrate nitrogen (NO₃^--N) content were the primary factors influencing the structure of soil nematode communities in the honey peach orchards. Thus, fertilization modes regulate community composition and diversity of soil nematodes by influencing soil physicochemical properties, especially pH and nitrate nitrogen levels.

Key words: soil nematode, community structure, high-throughput sequencing, fertilization measure, peach orchard