Abstract: Several tobacco endophyte strains were screened out, and their controlling effect against tobacco root-knot nematodes was studied with pot experiment. The fermentation broth of endophytic bacteria was more effective than the bacterial thallus, while that of endophytic actinomycetes was less effective than the actinomycete fermentation broth. All test endophytes promoted tobacco growth, and the promotion effect of their thalli was better than that of their fermentation broths. Endophytic bacterial strain H3 was the best in controlling tobacco root-knot nematode disease, with 91.68% controlling effect and a disease index of 4.16, much better than the treatments CK and avermectin. Moreover, the morphological feature of tobacco plant treated with H3 was better than that treated with avermectin.

Key words: Phytoplankton, Species composition, Community diversity, Coastal area of Pearl River estuary