Response of Soil Nematode Community Structure and Function to Monocultures of Pumpkin and Melon.

Dan Zhao,Hui Zhang,Yunhe Jia,Zuobiao Zhang,Hongyun Qu,Juan Wang,Yao Wang,Fan Yang,Yan Li,Ling Wen,Fengjuan Pan,Yixin Feng

doi:10.3390/life12010102

Abstract

It is well known that crop monoculture can induce negative effects on soil ecosystems and crop productivity. However, little is known about how vegetable monoculture affects the soil nematode community structure and its relationship with vegetable yields. In this study, the composition, abundance, metabolic footprint, and ecological indices of soil nematodes are investigated in monocultures of pumpkin and melon. The relationships between nematode community structure and yields of pumpkin and melon were analyzed by linear regression. Both monoculture soils of pumpkin and melon suppressed the relative abundance of bacterivores but increased the relative abundance of plant parasites. Pumpkin monoculture soils decreased soil nematode diversity but increased the maturity index of plant parasites. Monoculture soils of pumpkin and melon decreased the metabolic footprint of lower- and higher-level trophic groups of the soil food web, respectively. Pumpkin and melon monoculture soils increased the food web indices channel index (CI) but decreased the enrichment index (EI) and the structure index (SI). The monoculture soils of pumpkin and melon led to a more fungal-dominated decomposition pathway and degraded soil food web conditions. The abundance of bacterivores and food web indices EI and SI were positively correlated with soil nutrients and pH, while the abundance of plant parasites and CI were negatively correlated with soil nutrients and pH. Paratylenchus was negatively correlated with pumpkin and melon yields and could be the potential plant parasites threatening pumpkin and melon productions. Redundancy analysis showed that monocultures of pumpkin and melon altered the soil nematode community via soil properties; total N, total P, alkeline-N, and pH were the main driving factors.

Highlights

Monoculture is a very common practice in the intensive production of horticultural vegetables for profit-driving
The monoculture soils of pumpkin and melon increased the relative abundance of plant parasites and fungivores but decreased the relative abundance of bacterivores compared with 1-year cropping of pumpkin and melon, respectively (Figure 1)
Our findings suggest that vegetable monoculture soils shape the soil nematode community structure

Summary

Introduction

Monoculture is a very common practice in the intensive production of horticultural vegetables for profit-driving. Plant roots secrete the same exudates and provide the same straw degradant to the soil, resulting in changes in the soil physicochemical properties, microbial biomass and activity, and composition and function of soil biota and deeper changes in soil ecosystem function [1,2]. Harmful organisms are thought to build up over continuous monoculture, and this results in monoculture yield decline [3,4]. Previous studies on soil organisms in monoculture soils have mainly focused on pathogens [1]. Soil organisms are essential for maintaining soil health, which is one of the most important requirements for plant production in agricultural systems [5]. Increasing numbers of studies have reported that monoculture has

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