Abstract: Hainan Province is a significant tropical agricultural region in China. The warm and humid climate, combined with a high multiple cropping index, creates suitable ecological conditions for the proliferation of root-knot nematodes(RKNs). Owing to the environmental pollution and soil degradation, it is urgent to develop efficient, eco-friendly alternatives to chemical control. A Trichoderma strain named HLST30 was previously isolated from the rhizosphere soil of Hami melons in Hainan. Biocontrol efficacy of strain HLST30 against RKNs was evaluated in vitro. Upon treatment with strain HLST30 fermentation filtrate, the corrected mortality rates of second-stage juveniles of Meloidogyne incognita and M. graminicola reached 59.25% and 66.06%, respectively, at 72 h post treatment. The egg inhibition rates against the two RKNS were 47.33% and 52.59%, respectively, after incubation for 12 days. Meanwhile, after nine days of treatment, the parasitic efficacy of strain HLST30 against the two RKN species reached 64.18% and 56.61%. Scanning electron microscopy was used to observe the parasitic phenomenon of strain HLST30 towards M. graminicola eggs. Furthermore, the number of root galls on Hami melon and rice decreased by 42.59% and 55.43%, accordingly, in pot experiments. No significant effect was observed on the growth of Hami melon and rice after the treatment of strain HLST30. Combining morphological characteristics with molecular phylogenetic analyses, strain HLST30 was identified as T. ghanense. This study will provide a novel biological resource for the biological control of RKNs.

Key words: Meloidogyne incognita, Meloidogyne graminicola, Trichoderma ghanense, parasitism