Abstract: Root-knot nematodes are parasitic nematodes that seriously damage crops and distribute all over the world, which have a wide range of hosts. Preliminary tests showed that Aspergillus japonicus ZW1 fermentation filtrate had strong toxic effects on Meloidogyne incognita J2. However, the smooth surface pellet mycelia and radial surface pellet mycelia were produced during the fermentation process, and the fermentation filtrate from the two cultures had significantly different effect on mortality of nematodes. Fermentation filtrate of the strain ZW1 with smooth surface pellet mycelium had great nematicidal activity on M. incognita J2, with the corrected mortality of 100% at 24 h after exposure, significantly higher than that of radial surface pellet mycelia (12.7%). The culture conditions, such as temperature, rotation speed, medium, light and darkness of strain ZW1, were screened and analyzed, and the nematicidal activity of fermentation filtrate treated with boiling and 4℃ storage was determined. The results showed that optimal culture temperature and rotation speed of strain ZW1 were 25℃ and 150 r/min, respectively. Based on Czapek medium, the optimal carbon source, nitrogen source and amount were sucrose 30 g/L and KNO₃ 3 g/L, respectively. Nematicidal activity of strain ZW1 fermentation filtrate was not influenced by light and dark conditions, as well as boiling. Treated with strain ZW1 fermentation filtrate after storage at 4℃ for 1 year, the corrected mortality of J2 treated still reached 87.4%. The fermentation filtrate of strain ZW1 has great nematicidal activity on M. incognita J2, which is worthy of further research and development.

Key words: Aspergillus japonicus, Meloidogyne incognita, nutrient optimization, storage condition