Effects of Fusarium spp. carried by tobacco seeds on root rot occurrence of tobacco seedlings

In order to determine the status of tobacco seeds carrying Fusarium spp., Fusarium strains were isolated and purified from coated and naked seeds by petri dish culture method, followed by morphological and molecular analyses and the pathogenicity determination. Through moist germination of tobacco seeds on sterile filter paper and fungal plate culture in water agar, the fungus bearing rate of coated and naked seeds were found to be 0 - 10.00% and 5.00% - 85.00% respectively, and the proportion of Fusarium spp. in coated seeds of the isolated fungus strains was significantly lower than that in naked seeds. The identification results showed that the tested tobacco seeds carried Fusarium oxysporum, Fusarium graminearum, Fusarium incarnatum in Fusarium incarnatum-equiseti species complex, Fusarium citri, Fusarium ipomoeae, Fusarium lacertarum, Fusarium verticillioides in Gibberella fujikuroi species complex, Fusarium fujikuroi, and Fusarium andiyazi. The 21 purified Fusarium strains were all pathogenic to Zhongyan 100 and LY1306 seedlings, and the disease indexes were 21.11 - 100.00.