Interaction effects of P. polymyxa SC2 on pepper seedlings. In pot experiments, a pepper seedling was irrigated with 5 mL P. polymyxa SC2 cells (1 × 108 CFU/mL) and diluted with water to 200 mL. Control plant was irrigated with 5 mL sterilized LB medium diluted with water to 200 mL. At 30, 40, and 50 dpi, stem diameters (diameter at the ground base) were investigated. Panel (a) shows pepper stem diameters in healthy (H) soil and continuous cropping (C) soil. Values indicate means ± SD (n = 9; * P < 0.05, ** P < 0.01, Student’s t-test). Panel (b) is a representative image of the status of pepper in healthy soil at 40 dpi.