Study Of The Etiology And Biological Control On Rice Root-kont Nematode Disease In Fujian

A large area of rice root-knot nematode disease was first found in May2008in Zhenghe county, Nanping city, Fujan province. In this study, the symptoms of rice root-knot nematodes disease were described in detail. Meloidogyne graminicola was identified and determined by methods of morphology and molecular biology (rDNA-ITS-PCR BLAST analysis). And M.graminicola was first described in root-knot nematode disease in Fujian, China.Field investigations and the inoculation tests confirmed that Eccoilopus sp., Echinochloa sp., Cyperus sp., Leersia sp., Leptochloa chinensis, Alternanthera philoxeroid.es were natural and important intermediate host of M. graminicola. Inoculation experiment in indoor also showed that M. graminicola can infect tobacco, tomato, cucumber, etc.The root-knot nematode which parasitizing in gramineae weeds in surrounding rice fields and irrigation ditch was the main infection source of rice root-knot nematode disease. And the irrigation water was the main route of transmission of the disease.Biological characteristics of M. graminicola were studied and the results indicated that rice can be infected by M. graminicola in its whole growth stage. The life cycle period of M. graminicola was about20days at room temperature. The number of root knots produced increased as the inoculum level increased, and the symptoms were even more obvious. Rice root-knot nematodes can affect the growth of rice germ and radicle in sowing date, the seeds would not germinate if the number of rice root-knot nematodes was large. Water management status in rice fields had an effect on the infection and reproduction of the root-knot nematode in some degree. Rice roots still can be infected by M. graminicola in the submergence conditions, but the number of root knots was significantly reduced. The disease occurred slightly in long-term flooded fields as the infection and reproduction of nematodes were restricted. The disease occurred seriously in moist or irrigation soil which was beneficial to the infection and reproduction of nematodes.The culturable fungi of rice roots, rhizosphere soil and females were isolated and identified. The fungus of Trichoderma, Aspergillus, Penicillium, Fusarium, Cunninghamella, Monacrosporium were isolated from females of the rice root-knot nematodes. Trichoderma harzianum (FJ0904) with the highest pathogenicity to eggs of M. graminicola were obtained through the model "screened by chitin culture media and pathogenicity to the eggs of root-knot nematodes". T. harzianum was used for potted experiment, compared with the control group, the number of root knots of treatment group reduced by78.7%. And it had a good growth promoting effect on rice, which possess good application prospect. Fermentation process and preparation with high spore production were produced of the strain FJ0904.According to the survey results, the integrated control measures to rice root-knot nematode disease have been raised.