关键词: 豇豆枯萎病, 贝莱斯芽孢杆菌, 有机肥, 微生物多样性, 生物防治

Abstract:

【Objective】The objective of this study is to investigate the biological control effect of Bacillus velezensis SD13 against cowpea wilt when combined with different organic fertilizers, and to provide a theoretical basis for the application of biological control technology of cowpea wilt. 【Method】A pot experiment was conducted to evaluate the effects of applying 10% sheep manure, 10% vermicompost, and a 5% sheep manure+5% vermicompost mixture as fertilizer carriers on the efficacy of B. velezensis SD13 in controlling cowpea wilt. The experiment included eight treatments: blank control (CK), pathogen control (F), pathogen+SD13 (FB), pathogen+10% vermicompost (FW), pathogen+SD13+10% vermicompost (FBW), pathogen+10% sheep manure (FS), pathogen+SD13+10% sheep manure (FBS), and pathogen+SD13+5% vermicompost+5% sheep manure (FBWS). Each treatment was replicated three times, with three pots per replicate. After 45 d of cultivation in a greenhouse, the incidence rate of cowpea wilt, plant biomass (above-ground and below-ground dry weight), and defense enzyme activity (catalase) were measured for each treatment. Rhizosphere soil samples were collected, and the structure, diversity, and key microbial taxa of the soil bacterial community were analyzed using 16S rRNA high-throughput sequencing. 【Result】The control effect of sheep manure, vermicompost and mixed organic fertilizer combined with B. velezensis SD13 on cowpea wilt was more than 75%. The combination of sheep manure and SD13 significantly increased soil total nitrogen by 30%, with the dominant soil bacteria being Firmicutes, which showed a negative correlation with other bacterial communities. The combination of vermicompost and SD13 significantly increased the above-ground dry weight of diseased cowpea plants by 29% and the below-ground dry weight by 30%, enhanced the activity of catalase in cowpea by 10%, and significantly increased the richness and diversity of soil bacteria, restoring the community structure to a healthy level. The combination of mixed organic fertilizers and SD13 significantly increased the below-ground dry weight of diseased cowpea plants by 155%, with the soil community structure being influenced by the microbial communities of both vermicompost and sheep manure. 【Conclusion】The type of organic fertilizer affects the biocontrol effect of B. velezensis SD13 against cowpea wilt in the soil. Vermicompost is more suitable for combination with SD13 than sheep manure. This combination not only ensures high biocontrol effect, but also further enhances cowpea biomass, catalase activity, and soil bacterial richness and diversity. It increases the abundance of beneficial bacterial communities and restores the soil bacterial community structure and composition to levels associated with healthy cowpea soil, making it a suitable organic fertilizer for the application of SD13 in controlling cowpea wilt in soil.

Key words: cowpea wilt, Bacillus velezensis, organic fertilizer, microbial diversity, biological control