Spatial Differentiation and Influencing Factors of Hongju Germplasm Resources in Zizhong County Based on GeoDetector

Based on 21,321 valid survey records representing 108,411 Hongju (Citrus reticulata Blanco) trees, GIS-based spatial analysis, 500-m grid statistics, and the GeoDetector model were used to examine spatial differentiation and the explanatory power of environmental factors. The records were distributed across 2,027 non-empty grid cells and showed a core–periphery pattern, with high-value grids concentrated in western and central Zizhong County. Under the five-class main scheme, elevation had the highest explanatory power (q=0.1043, P=0.001), slope had weak but significant explanatory power (q=0.0058, P=0.024), and distance to rivers showed no significant independent effect (q=0.0032, P=0.141); the interaction between elevation and slope had the highest explanatory power (q=0.1316). Sensitivity analysis indicated that elevation and elevation-related interactions were relatively stable. Survey attributes showed that 62% of the resources originated from legacy plantings, 99.88% were maintained by smallholders, and 80% occurred in homesteads, courtyards, orchards, or cropland. These results provide a basis for the spatially targeted conservation of local citrus germplasm resources.