Changes in Rhizosphere Microbial Community of Potato under Farmland with Different Cultivation Years in Alpine-cold Region

Soil quality and microbial community structure are highly responsive to tillage-induced feedback. Prolonged tillage inevitably leads to soil degradation and alterations in the rhizosphere microbial community. However, the impacts of tillage duration and soil quality on microbial communities in Alpine-cold regions remain insufficiently explored. To address this, farmlands with 0, 5, 20, and 60 years of tillage were selected, and a "space-for-time" approach was employed to examine the dynamic changes and functional shifts in rhizosphere microbial communities across varying tillage durations. The results revealed that bacterial community diversity initially increased, then decreased, and subsequently increased again with longer tillage periods, while community richness exhibited a pattern of initial decline followed by recovery. Fungal community abundance consistently decreased with prolonged tillage, eventually stabilizing. The abundance of Proteobacteria showed a positive correlation with soil nutrient changes (an increase of 111%), whereas Actinobacteria displayed a negative correlation (a decrease of 59.14%). Distinct bacterial biomarkers were identified at different tillage durations, while fungal biomarkers rapidly declined with extended tillage. Soil available potassium (AK) emerged as the primary environmental factor influencing both bacterial and fungal communities. Long-term tillage significantly elevated the abundance of aerobic chemoheterotrophs, chemoheterotrophs, urea-decomposing bacteria, organic matter-decomposing bacteria, fungal plant pathogens, and endophytic fungi. Variance partitioning analysis (VPA) revealed that soil quality and tillage duration had a more substantial impact on bacterial communities than on fungal ones. Overall, the findings suggest that long-term tillage profoundly affects rhizosphere microbial communities and their functional potential, with a more pronounced influence on bacterial than fungal communities.