Effect of continuous cropping of hot pepper on soil bacterial community

Abstract:

[Objective] Soil microorganisms are essential for the long-term sustainability of agricultural ecosystems. This study aims to explore the effects of continuous cropping of hot pepper on the structure and function of soil bacterial community. [Methods] We employed high-throughput sequencing of 16S rRNA and PICRUSt-based functional prediction to investigate the bacterial abundance, diversity, community composition, and potential functional component in the soils with continuous cropping of hot pepper for 1, 3, 5, and 10 years (1Y, 3Y, 5Y, and 10Y, respectively). [Results] The Shannon index and co-occurrence network complexity of soil bacteria decreased with the extension of continuous cropping years. The bacterial community structure was markedly affected by the years of continuous cropping, and different bacterial populations had varied responses to continuous cropping. Long-term continuous cropping increased the relative abundance of Proteobacteria and Bacteroidetes, while decreasing that of Chloroflexi, Acidobacteria, Firmicutes, and Patescibacteria. Furthermore, PICRUSt-based functional prediction showed that the continuous cropping changed the overall nitrogen and phosphorus metabolism of soil bacteria. After long-term continuous cropping, the functional genes in energy metabolism, amino acid metabolism, and carbohydrate metabolism showed reduced relative abundance, while those involved in folding, classification and degradation, replication and repair, membrane transport, and cell growth and death had increased relative abundance. The results of redundancy analysis indicated that soil organic matter and available phosphorus were the key factors associated with the migration and functional changes of soil bacteria. [Conclusion] After long-term continuous cropping of hot pepper, the change of community structure and the decline of diversity to the dysfunction of soil microbial community, which may be one of the reasons for the continuous cropping obstacles of hot pepper.