Long-Term Monoculture Negatively Regulates Fungal Community Composition and Abundance of Tea Orchards

Continuous cropping frequently leads to soil acidification and major soil-borne diseases in tea plants, resulting in low tea yield. We have limited knowledge about the effects of continuous tea monoculture on soil properties and the fungal community. Here, we selected three replanted tea fields with 2, 15, and 30 years of monoculture history to assess the influence of continuous cropping on fungal communities and soil physiochemical attributes. The results showed that continuous tea monoculture significantly reduced soil pH and tea yield. Alpha diversity analysis showed that species richness declined significantly as the tea planting years increased and the results based on diversity indicated inconsistency. Principal coordinate analysis (PCoA) revealed that monoculture duration had the highest loading in structuring fungal communities. The relative abundance of Ascomycota, Glomeromycota, and Chytridiomycota decreased and Zygomycota and Basidiomycota increased with increasing cropping time. Continuous tea cropping not only decreased some beneficial fungal species such as Mortierella alpina and Mortierella elongatula, but also promoted potentially pathogenic fungal species such as Fusarium oxysporum, Fusarium solani, and Microidium phyllanthi over time. Overall, continuous tea cropping decreased soil pH and potentially beneficial microbes and increased soil pathogenic microbes, which could be the reason for reducing tea yield. Thus, developing sustainable tea farming to improve soil pH, microbial activity, and enhanced beneficial soil microbes under a continuous cropping system is vital for tea production.