Response of soil fungal community to pruning intensity in Rubus corchorifolius rhizosphere.

Elucidating the response of rhizosphere fungal communities to pruning intensity in Rubus corchorifolius is critical for refining branch-thinning practices and optimizing rhizosphere soil management. Taking 2-year-old branches of R. corchorifolius as research materials, we set three pruning intensities: no basal pruning (control), removal of 1/5 of primary lateral branches (light thinning), and removal of 1/3 of primary lateral branches (heavy thinning). We conducted pruning 15 days before the flowering period and collected rhizosphere soil at early flowering stage, early fruiting stage, and fruit ripening stage to analyze the changes in soil nutrient content and fungal community structure and function. The results showed that at early flowering and early fruiting, light thinning increased soil organic matter, organic carbon, total nitrogen, available nitrogen, and available potassium by 4.5%-44.1%, whereas heavy thinning decreased organic matter, organic carbon, total nitrogen, and available nitrogen by 2.5%-18.2%. At fruit ripening stage, all thinning treatments significantly elevated total phosphorus, organic matter, organic carbon, available nitrogen, available phosphorus, C/N, and C/P, with increases ranging from 9.2% to 136.8%. Thinning reduced fungal community diversity at early flowering and early fruiting, but increased richness at fruit ripening. Light thinning enriched Russula at early flowering and Mortierella and Archaeorhizomyces at early fruiting, while heavy thinning enriched Isaria at early flowering and Hydnum at fruit ripening. Redundancy analysis indicated that community composition under both thinning treatments was positively modulated by available potassium at early flowering and early fruiting stage, and by available nitrogen (light thinning) and available phosphorus (heavy thinning) at the ripening stage. Pruring increased the proportion of soil saprotrophs at fruit ripening stage and the mycorrhizal fungal fraction during early flowering and early fruiting stage. Overall, light thinning performed half a month before flowering could favor soil nutrient accumulation, improve fungal community structure, and increase the relative abundances of saprotrophs and mycorrhizal fungi, collectively exerting positive effects on soil nutrient cycling and growth of R. corchorifolius.