Different responses of rhizosphere and non-rhizosphere soil microbial communities to consecutive Piper nigrum L. monoculture.

Zhigang Li,Chao Zu,Huasong Wu,Jianfeng Yang,Can Wang,Huan Yu

doi:10.1038/srep35825

Abstract

Soil microorganisms have important influences on plant growth and health. In this study, four black pepper fields consecutively monocultured for 12, 18, 28 and 38 years were selected for investigating the effect of planting age on rhizosphere and non-rhizosphere soil microbial communities and soil physicochemical properties. The results revealed that the relative abundance of the dominant bacterial phyla in rhizosphere soil increased considerably with long-term consecutive monoculture but decreased in non-rhizosphere soil with a significant decline in Firmicutes. For fungi, an increasing trend over time was observed in both rhizosphere and non-rhizosphere soils, with the abundance of the pathogenic fungi Fusarium increasing significantly accompanied by a decrease in the bacteria Pseudomonas and Bacillus that is beneficial for black pepper. Consecutive monoculture, especially for 38 years, considerably decreased soil microbial diversity. Additionally, the rhizosphere soil pH and organic matter and available K contents decreased with increasing planting duration, though available N and P increased. All soil nutrient contents and microbial diversity indices were higher in rhizosphere soil compared to non-rhizosphere soil. The results suggest that long-term consecutive monoculture leads to variations in soil microbial community composition and physicochemical properties in both rhizosphere and non-rhizosphere soils, thus inhibiting the black pepper growth.

Highlights

Soil microorganisms have important influences on plant growth and health
After filtering reads according to basal quality control and singleton operational taxonomic unit (OTU) removal, 1,477,241 sequences comprising 9,665 of bacterial OTUs were obtained from 24 samples
Nitrospira, Armatimonadetes, Cyanobacteria and WS3 were present in most soils but at relatively low abundance (ARA: 0.1–1%)

Summary

Introduction

Four black pepper fields consecutively monocultured for 12, 18, 28 and 38 years were selected for investigating the effect of planting age on rhizosphere and non-rhizosphere soil microbial communities and soil physicochemical properties. The results suggest that long-term consecutive monoculture leads to variations in soil microbial community composition and physicochemical properties in both rhizosphere and non-rhizosphere soils, inhibiting the black pepper growth. Hainan Province, the major producer and exporter in China, cultivates 22,000 ha of P. nigrum and produces 3.6 × 107 kg of dried peppercorns annually, comprising 90% of the pepper production in China This constitutes an important tropical crop industry in China, with an output value of more than 15 million USD6. Slow decline/wilt, Phytophthora foot rot disease and root-knot nematodes are the major black pepper diseases These three kinds of diseases occur and spread more frequently in long-term consecutive monocultured black pepper fields[5,7]. Changes of the abundance of the pathogenic fungus Fusarium and the antagonistic bacteria Pseudomonas and Bacillus in the black pepper soil with the planting age has not been reported

Methods

Results

Conclusion