Abstract: To achieve higher effect of bio-control on cucumber Fusarium wilt, as well as promote the growth of cucumber, the fermentation media and conditions of the marine antagonism combination ST-2 which contains strains of GQ-17, YH-91 and YH-23 were studied. The synergistic interaction and antimicrobial activity of the three bio-control strains were determined by co-culture and Oxford cup methods in dish, respectively. The best fermentation medium and the optimal inoculation condition were determined by single-factor experiment and orthogonal experiment respectively, and the bio-control effects of ST-2 against cucumber Fusarium wilt were detected by pot experiment. Strains GQ-17, YH-91 and YH-23 were symbiotic and had no inhibition with each other. Inhibition zone of their fermented liquid against Fusarisum oxysporum f. sp. cucumebrium were 24.2, 20.4 and 14.4 mm, respectively. The best fermentation medium for ST-2 was screened out, which contains ingredients as follows: corn flour 8 g/L, soybean meal 10 g/L, sodium chloride 2.5 g/L, calcium carbonate 2.0 g/L, and nature pH. The fermented broth has the highest inhibition activity on cucumber wilt when the combination ratio of GQ-17, YH-91 and YH-23 was 3:3:2 (V/V), and the inoculation ratio was 3%, into 50 mL liquid medium in 250 mL triangular flask, shaking at 31 ℃ for 5 d with 150 r/min. The relative control effect was 65.89%, which was higher than the effect of single strain (19.94%, 25.20%, and 42.88%) and shenqinmycin (39.50%). In addition, the increments of stem length (9.70 cm) and diameter of plant (0.77 mm) were significant increased by 29.75% and 12.69%, respectively.

Key words: synergistic interaction, combination, fermentation condition optimizing, cucumber Fusarium wilt