Study on Identification of Tobacco Variety Resistance to Fusarium oxysporum

To obtain suitable identifying methods of tobacco root rot resistance in different tobacco varieties(Xiaohuangjin1025, Zhongyan100, Changbohuang, 664-01), the inoculation crude toxin of tobacco seedlings, spore suspension culture, inoculation of grain culture with fungi, inoculation mycelial cake of detached leaf and local injection of oxalic acid were investigated. The results showed that crude toxin stress could identify the resistance degree of tobacco varieties, and the suitable system was treated within 6 d at 8% toxin concentration. The inoculation spore suspension could identify the degree of resistance of different varieties and the suitable system was treated within 4 d and with 10⁷ spores per mL. The inoculation of grain culture with fungi could also identify the degree of resistance of tobacco varieties, and the suitable system was treated within 9 d at the toxin concentration of 20% pathogenic fungus grain culture. The treatment of detached leaf with mycelial cake oxalic acid could distinguish the resistance of varieties, but could not differentiate the degree of resistance. The results showed that the spore suspension inoculation method and the fungal wheat culture inoculation method could accurately evaluate the resistance of varieties to Fusarium root rot compared with the other three methods.