Effects of marigold straw compost on alleviating continuous cropping obstacles of tobacco

【Objective】In order to alleviate the continuous cropping obstacles of tobacco,the effects of applying marigold straw compost on the physicochemical properties,rhizospheric microbial community and the occurrence of tobacco bacterial wilt were explored in field experiments.【Method】The experiment was conducted from 2018 to 2020. Marigold straw compost was added each year either at 1500 kg/ha(FMC) or with 0 kg/ha as a control(CK). In the third year of applying marigold straw compost(2020),the samples of rhizosphere soil were collected at 50 and 100 days after tobacco transplanting. The soil physicochemical indexes,soil bacterial and fungal community structures and the occurrence of tobacco bacterial wilt were investigated.【Result】Compared with CK,the application of FMC significantly increased soil pH and organic matter content(P<0.05, the same below),while the contents of alkali-hydrolyzable nitrogen,available phosphorus and rapidly available potassium had no significant changes(P>0.05). The application of FMC could also significantly increase the Sobs and Chao1 indices of the soil bacterial community,but little effects on the diversity of the fungal community had been shown. The application of FMC also improved the microbial community structure and increased the relative abundance of some antagonistic fungi(such as Mortierella, Chaetomium),while decreasing the relative abundance of some soil-borne pathogens(such as Ralstonia,Fusarium). The application of FMC for three years significantly reduced the incidence and disease index of tobacco bacterial wilt,and the relative control effect on tobacco bacterial wilt was 47.72%.【Conclusion】The application of FMC could improve the physicochemical properties and rhizospheric microbial community structure in the soil during tobacco cultivation,with a reduction in the incidence of tobacco bacterial wilt. The use of FMC effectively alleviates the obstacles to the continuous cropping of tobacco.