Biocontrol effect of the complex inoculants of Trichoderma and Bacillus amyloliquefaciens on chrysanthemum white rust

In this study, the Chrysanthemum morifolium susceptible cultivar ‘Jinba’ was used as the experimental material to perform prevention and treatment testing of complex inoculants of Trichoderma on chrysanthemum white rust (CWR) and growth promotion and disease-prevention testing of Bacillus amyloliquefaciens. The treatment test results showed that the number of teliospores in the diseased leaves treated with the complex inoculants of Trichoderma was considerably reduced, and the germination of teliospores was inhibited. The results of the prevention experiment showed that test group two (T2) significantly reduced the infection rate of pathogens and enhanced the SOD, POD, CAT, PPO, PAL and CHI compared to the control group and test group one (T1). The RT-qPCR results revealed that T2 could induce the up-regulation of the NPR1, PAL, COI1, and PDF1.2 genes. The treatment of B. amyloliquefaciens root irrigation promoted the growth of ‘Jinba’. The plant height, fresh aboveground weight, fresh underground weight, root-shoot ratio, and root activity increased by 5.38%, 31.67%, 64.63%, 5.26%, and 283.33%, respectively. Moreover, the activities of soil protease, urease, sucrase, and phosphatase increased significantly. The incidence of CWR in the field decreased by 20.0%. In summary, the complex inoculants of Trichoderma can significantly inhibit the germination of teliospores, reduce the infection rate of pathogens and improve the resistance of CWR by inducing the enhancement of related enzyme activity and the up-regulation of disease-resistant gene expression. B. amyloliquefaciens can promote plant growth by increasing soil enzyme activity, thereby reducing the incidence of CWR.