Succession Pattern in Soil Micro-Ecology Under Tobacco (Nicotiana tabacum L.) Continuous Cropping Circumstances in Yunnan Province of Southwest China.

Dan Chen,Jiapan Lian,Mei Wang,Song Yu,Mehr Ahmed Mujtaba Munir,Xiaoe Yang,Kuai Dai,Yujie Zhou

doi:10.3389/fmicb.2021.785110

Abstract

Continuous cropping obstacle (CCO) is a common phenomenon in agricultural production and extremely threatens the sustainable development of agriculture. To clarify the potential keystone factors causing tobacco (Nicotiana tabacum L.) CCO, tobacco plants, topsoil, and rhizosphere soil were sampled from the fields with no, slight, and severe tobacco disease in Dali and Yuxi of Yunnan province in China. The physicochemical properties of topsoil and rhizosphere soil, the phenolic acids (PAs) contents in rhizosphere soil, and elemental contents in topsoil, rhizosphere soil, and tobacco plants were analyzed. Microbial diversity in rhizosphere soil was determined by the metagenomic sequencing method. The results showed that soil pH, texture, cation exchange capacity, organic matter, TC, TN, and available K contents showed a significant difference (p < 0.05) in soil physicochemical properties. There was a deficiency of B, K, Mg, and Mn contents in soil and/or tobacco plants. The contents of PAs, especially syringic acid in rhizosphere soil, varied significantly among the three sampling groups (p < 0.05). Meanwhile, microbial communities and functional genes changed from beneficial to harmful, showing an intimate correlation with soil pH and syringic acid content. It can be concluded that tobacco CCO could be allocated to the imbalance of soil micro-ecology, which possessed a regional feature at the two sampling sites.

Highlights

Continuous cropping (CC) in the same field has been widespread in China and even all over the world as the result of the limited soil resources, the driving of economic benefits, and the lack of reasonable cropping concept (Zhang et al, 2013; Yuan et al, 2014)
For the NO3-N content, there was no apparent pattern in the topsoil or rhizosphere soil from Dali or Yuxi
The available K content in the topsoil decreased apparently in the severely diseased groups. It showed an opposite trend in the rhizosphere soil from Dali and Yuxi

Summary

Introduction

Continuous cropping (CC) in the same field has been widespread in China and even all over the world as the result of the limited soil resources, the driving of economic benefits, and the lack of reasonable cropping concept (Zhang et al, 2013; Yuan et al, 2014). There are three main causes of CCO, namely, deterioration of soil physicochemical properties, accumulation of plant allelopathic substances (primarily phenolic acids), and altered soil microbial diversity, which can be collectively referred to as imbalance of soil micro-ecological environment (Zhou and Wu, 2012; Yin et al, 2016; Chen et al, 2018; Bai et al, 2019). Unique PAs can accumulate in the soil after year’s and year’s cropping of the same plant This phenomenon has been demonstrated in the rhizosphere soil of CC plants, such as tobacco (Bai et al, 2019; Chen et al, 2019). Soil microbial communities are crucial to plant establishment and normal growth (Epelde et al, 2010)

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