Abstract
Marigold is reported to have antibacterial activity, and effectively protect crops against soil-borne diseases. However, it is not known whether and how tobacco bacterial wilt (TBW) could be mitigated via intercropping with marigold under field conditions. In this study, a field experiment was performed to measure and compare the occurrence of TBW, the soil chemical properties, and soil microbial composition and diversity between a tobacco-marigold intercropping system and a tobacco monocropping system. At 100 days (d) post-transplantation, the incidence (I) and disease index (DI) for the tobacco-marigold intercropping system were 30.12% and 58.25% lower than that for tobacco monocropping system, respectively. The results showed that Sobs, Shannon and Chao 1 index of soil bacterial communities in the tobacco-marigold intercropping system were 10.34%, 1.41% and 5.13% higher than that in the tobacco monocropping system at 100 d post-transplantation, respectively. It exhibited a higher richness and diversity of soil bacterial communities in the tobacco-marigold intercropping system. The relative abundance of some beneficial genera in tobacco-marigold intercropping system, such as Lysobacter, Burkholderia, Trichoderma, Mortierella, Chaetomium, Penicillium, was 1.50, 1.61, 3.35, 1.67, 4.40 and 4.50 fold higher than that in tobacco monocropping system. The presence of the intercropping system inhibited soil acidification and loss of soil calcium ions. The redundancy analysis (RDA) indicated that soil pH and exchange Ca2+ were the main environmental factors which seemed to influence the bacterial and fungal community. The results from this study provided valuable insight into the possible mechanisms enhancing soil health in the tobacco-marigold intercropping system.
Highlights
IntroductionMany studies have indicated that use of the monocropping system, a very common worldwide agricultural practice, can inhibit plant growth and is associated with the development of serious soil-borne diseases, bacterial wilt (Hiddink et al 2009; Larkin et al 2011; Yang et al 2012; Zhang et al 2013; Guo et al 2014; Liu et al 2014)
Tobacco bacterial wilt (TBW), caused by Ralstonia solanacearum phylotype I, is one of the major soil-borne diseases affecting cultivated tobacco (Nicotiana tabacum) (LiuElectronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.It was previously reported that the frequency of tobacco bacterial wilt (TBW) has increased with the persistence of monocropping (Shiomi et al 1999; Niu et al 2017)
Different capital letters in the same column represented the incidence and disease index of tobacco bacterial wilt showed significant differences at p < 0.01 based on T-test between C-field and I-field indicating that 3 years of intercropping effectively restrained the incidence and severity of TBW
Summary
Many studies have indicated that use of the monocropping system, a very common worldwide agricultural practice, can inhibit plant growth and is associated with the development of serious soil-borne diseases, bacterial wilt (Hiddink et al 2009; Larkin et al 2011; Yang et al 2012; Zhang et al 2013; Guo et al 2014; Liu et al 2014). By maintaining multiple crop species in an ecosystem, intercropping can help in increasing the activity and diversity of rhizosphere soil microorganisms (Li et al 2014), optimizing microbial community structure (Wu et al 2018; Tian et al 2019), and preventing crop. As a consequence, intercropping is more widely utilized in Asia, Latin America, America and Africa, and is roundly popular with farmers worldwide (Ratnadass et al 2012; Boudreau 2013)
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