Abstract: Root-knot nematode Meloidogyne incognita is an important soil-borne disease that threatens the safety of vegetables. Effective control measures are in urgent need. In this study, a biocontrol fungal strain NF-06 was isolated from the egg masses of M. incognita, identified as Clonostachys rosea by morphological and rDNA-ITS sequence analysis. An initial assay of NF-06 culture filtrates on second-stage juveniles was conducted, which showed relative mortalities of 63.6%, 75.5% and 87.0% at 24 h, 48 h and 72 h post treatment, respectively. The solid state fermentation conditions of the strain NF-06 were optimized using the conidium number as an index. The results showed that the optimal basal medium was the mixture of wheat bran and wheat straw, with a mass ratio of 4:1 (wt/wt). When corn flour (10%), broad bean (2%) and KH₂PO₄(0.05%) were supplemented into the basal medium, the maximum conidial production was achieved. The viable conidial number reacheed 8.9×10¹⁰ CFU/g at the optimal culture conditions of initial pH 7.0, initial water content 40%, and inoculum dose 5%. The NF-06 solid culture significantly reduced the population densities of juveniles in soil and root-knot index in tomato in a greenhouse test. When hole applied at 5 g per plant, the NF-06 solid culture afforded reduction rates of juveniles and control efficiency of 67.9% and 69.6%, respectively. This study provides a basis for the research and development of bio-nematicide.

Key words: root-knot nematode, Clonostachys rosea, biological control, fermentation condition optimizition