Abstract
The continuous cropping of plants can result in the disruption of the soil microbial community and caused significant declines in yields. However, there are few reports on the effects of continuous cropping of sugarcane on the microbial community structure and functional pathway. In the current study, we analyzed the structural and functional changes of microbial community structure in the rhizospheric soil of sugarcane in different continuous cropping years using Illumina Miseq high-throughput sequencing and metagenomics analysis. We collected rhizosphere soils from fields of no continuous cropping history (NCC), 10 years of continuous cropping (CC10), and 30 years of continuous cropping (CC30) periods in the Fujian province. The results demonstrated that continuous sugarcane cropping resulted in significant changes in the physicochemical properties of soil and the composition of soil bacterial and fungal communities. With the continuous cropping, the crop yield dramatically declined from NCC to CC30. Besides, the redundancy analysis (RDA) of the dominant bacterial and fungal phyla and soil physicochemical properties revealed that the structures of the bacterial and fungal communities were mainly driven by pH and TS. Analysis of potential functional pathways during the continuous cropping suggests that different KEGG pathways were enriched in different continuous cropping periods. The significant reduction of bacteria associated with rhizospheric soil nitrogen and sulfur cycling functions and enrichment of pathogenic bacteria may be responsible for the reduction of effective nitrogen and total sulfur content in rhizospheric soil of continuous sugarcane as well as the reduction of sugarcane yield and sugar content. Additionally, genes related to nitrogen and sulfur cycling were identified in our study, and the decreased abundance of nitrogen translocation genes and AprAB and DsrAB in the dissimilatory sulfate reduction pathway could be the cause of declined biomass. The findings of this study may provide a theoretical basis for uncovering the mechanism of obstacles in continuous sugarcane cropping and provide better guidance for sustainable development of the sugarcane.
Highlights
Soil microorganisms are essential and play critical roles in soil organic matter decomposition, nutrient availability, and cycling, and in some instances, improve stress tolerance or suppress pathogens to regulate the soil-borne diseases (Van Der Heijden et al, 2008; Sun et al, 2015)
We have shown that continuous cropping in sugarcane cultivation led to significant declines in soil pH, organic matter (OM), total nitrogen (TN), total sulfur (TS), TK, and Available nitrogen (AN) contents
The metagenomic sequencing and analysis confirmed our proposed hypothesis that continuous cropping reduces the diversity of bacterial and fungal communities and that soil microbial community structure and function were significantly affected by the continuous sugarcane cropping system
Summary
Soil microorganisms are essential and play critical roles in soil organic matter decomposition, nutrient availability, and cycling, and in some instances, improve stress tolerance or suppress pathogens to regulate the soil-borne diseases (Van Der Heijden et al, 2008; Sun et al, 2015). This complex plant-associated microbial community, is referred to as the second genome of the plant (Berendsen et al, 2012). The study on soil microorganisms has a great potential to provide essential new insights into the impact of microbial diversity on plant growth and soil ecosystem functioning
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