Abstract: Soil protozoa can regulate microbial community structure in the rhizosphere by preying on bacteria and fungi, and thus play a non-negligible role in plant growth. To understand the seasonal variations of the composition and diversity of the protozoan community in the rhizosphere soil of Actinidia arguta in the cold-region of Northeast China, we selected Actinidia arguta (LD133) germplasm resource orchard of Jiamusi University and collected the surface and subsurface soils of the rhizosphere of LD133 in March, June, September, and December 2023. Soil ciliate groups were cultivated and identified by non-flooding culture method and in vivo observation method. A total of 71 species of soil ciliates were identified, belonging to 3 classes, 11 orders, 29 families, and 46 genera. The dominant orders were Hypotrichida, Colpodida, and Hymenostomatida. The diversity indices of surface and subsurface soils in June were the highest. There were significant differences in the composition of ciliate communities in the subsurface soil in June and the surface soil in September, indicating the niche differentiation of ciliates. Soil pH varied among different seasons. Specifically, soil pH of the surface layer was the lowest in March (4.93), and soil pH of the subsurface layer was the highest in September (6.68). Most ciliates could survive within a relatively wide pH range. Soil organic matter, total nitrogen, NO₃^--N contents were correlated with evenness index (E), dominance index (D) and diversity index (H) of soil ciliate community. Our results clarified the complexity of the ciliate groups of protozoa in the rhizosphere soil of Actinidia arguta in different seasons, providing data support for in-depth understanding of the microecological balance of the rhizosphere soil of vines.

Key words: Actinidia arguta, rhizosphere, soil, ciliate, seasonal variation