Changes in Cucumber Rhizosphere Bacillus spp. Abundance and Community Structure During Long-Term Continuous Monocropping
Muhammad Khashi u Rahman 1, 2  
,   Changli Ma 1, 2  
,   Fengzhi Wu 1, 2  
,   Xingang Zhou 1, 2  
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Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Northeast Agricultural University, Harbin, China
College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin, China
Xingang Zhou   

Northeast Agricultural University, China
Submission date: 2020-01-12
Final revision date: 2020-03-25
Acceptance date: 2020-04-02
Online publication date: 2020-11-26
Continuous monocropping has been a traditional way of cropping system in most parts of the world. It is important to study its effects on soil microbial communities, which are important element of any agroecosystem functioning and for both plant and soil health. In this study, we used real-time PCR and PCR-denaturing gel electrophoresis (PCR-DGGE) techniques to analyze changes in Bacillus spp. abundance, diversity and community structure in continuously monocropped cucumber (Cucumis sativus L.) rhizosphere during nine cropping seasons (after every 2 seasons i.e. 1, 3, 5, 7, 9). Results showed that continuous monocropping significantly changed the Bacillus spp. abundance, diversity and community structure, and the effect was in course of time. The abundance of Bacillus spp. increased up to 5th cropping season and then decreased in following cropping seasons. The number of DGGE bands, Shannon-Wiener Index and Evenness indexes decreased during 3rd cropping season and, after that, increasing trend was observed up to 9th cropping season. These results suggest that the diversity of crop specific Bacillus spp. might start increasing but overall abundance of those keep decreasing after a specific period of time during long-term cucumber continuous monocropping.