Long-term orchard-floor mulching alters soil fungal assemblages, nutrient status, and peach fruit traits

Abstract

Orchard-floor mulching is widely used for weed suppression in perennial fruit systems, yet its effects on soil fungal communities and their links to soil nutrient status and fruit traits remain insufficiently understood. Here, we conducted a 6-year field experiment in a peach orchard to compare three orchard-floor management practices: barrier fabric (BF), hairy vetch (HV), and ryegrass (RG). Soil physicochemical properties, fruit traits at harvest, and soil fungal communities were evaluated, and treatment-responsive fungal modules were identified by integrating differential abundance analysis, indicator species analysis, and co-occurrence network analysis. Compared with the other treatments, HV was associated with higher fruit weight and a higher total sugar-to-total acid ratio (TS/TA). Mulching treatments significantly altered soil physicochemical properties and fungal community composition, whereas fungal alpha diversity showed limited overall responses. Three candidate treatment-responsive fungal modules were preferentially enriched under BF, HV, and RG, respectively, and differed in both taxonomic composition and their associations with soil nutrient variables. Fruit weight was positively correlated with soil NO 3 -- N and NH 4 + -N and negatively correlated with soil pH, whereas flavor-related traits were positively correlated with AN, NH 4 + -N, NO 3 -- N, and dissolved organic carbon (DOC). Overall, long-term mulching was associated with shifts in soil fungal assemblages, and these assemblages were linked to soil nutrient conditions and fruit traits. This study provides a fungal community perspective on how orchard-floor management may be associated with soil–plant interactions in peach orchards.