Resistance Degree of Radish Cultivars to Fusarium oxysporum f. sp. raphani according to Several Conditions

This study was conducted to establish the efficient screening system for resistant radish to Fusarium oxysporum f. sp. raphani. Five radish cultivars ('Myoungsan', 'Chungdu', 'Jangsaeng', 'Hannongyeorm', and 'Chungsukungjung') showing different degree of resistance to the fungus were selected. And the development of Fusarium wilt of the cultivars according to several conditions such as root wounding, dipping period of roots in spore suspension, inoculum concentration, and incubation temperature to develop the disease was tested. In distinguishing the resistance degree of the radish cultivars to the disease, non-cut roots were more effective than cut roots. And occurrence of Fusarium wilt of the radish plants increased in the proportion to increase of root-dipping period and spore concentration of the fungus. Thus, optimum conditions to differentiate susceptible and resistant cultivars to the disease were root-dipping period of 0.5 hour and spore concentration of 1 × 10 7 conidia·mL -1 . Disease severity of Fusarium wilt on the cultivars was changed with incubation temperature and the radish seedlings incubated at 25℃ represented the most difference of resistance and susceptibility to Fusarium wilt. From the above results, we suggest that the efficient screening method for resistant radish to Fusarium oxysporum f. sp. raphani would be to dip non-cut roots of fourteen-day-old radish seedlings in spore suspension of 1 × 10 7 conidia·mL -1 for 0.5 hour and to transplant the inoculated plants to plastic pots with fertilized soil, and then to incubate the radish plants at a temperature of 25℃ for development of Fusarium wilt.