Abstract: B. velezensis B006 is a strain with high biocontrol efficiency. However, its efficacy under different fertigation conditions has not been clarified. The plant growth and soft rot disease control of Chinese cabbage affected by the application of B006 agent combined with different soil water content and fertilization were first examined in pot experiment, and the results showed that application of B006 agent at a dosage of 5g (1×10⁷ CFU/g) in each planting furrow during sowing the seeds following pre-dripping of B006 suspension (3×10⁸ CFU/mL) obviously reduced the incidence and severity of soft rot disease when the soil water content was at 14% and fertilization was 3.57 g/kg soil. The control efficacy reached 77.4% in comparison with non-B006 treatment at the same condition. A field trial which combined the application of B006 agent with fertilization, soil water potential in a randomized block interactive design was carried out in the greenhouse, and the results showed that yields increased by 8.6% and 11.2% in B006 treatments under combination of soil water potential and fertilization amount at -50 kPa×1049.5 kg/hm² (N/P/K=18/5/13), in comparison with non-B006 treatments at the conditions of -50 kPa×1499.3 kg/hm² and -30 kPa×1499.3 kg/hm², respectively. In summary, the application of B. velezensis B006 under the conditions of less water and fertilizer can significantly control the occurrence of cabbage soft rot, promote plant growth, and increase the cabbage yield.

Key words: water potential, fertilization amount, B. velezensis B006, soft rot disease, growth and yield promotion