Abstract: To establish a quick, convenient and reliable method for evaluating lettuce cultivar resistance, the effects of four factors (soft rot pathogens, inoculation methods, seeding ages, and time of disease investigation) on the incidence of bacterial soft rot disease on lettuce were investigated. Furthermore, we identified the resistance of 50 lettuce varieties mainly cultivated in North China through this method and repeated the experiments in spring and autumn. These results will benefit for the selection and application of lettuce resistant materials. The results showed that the method with the pathogen Pectobacterium carotovorum subsp. brasiliensis BC1, inoculating plants at the seedling age of 7-8 true leaf stage by pin prick and investigating the disease at 48 hours after inoculation, was suitable for identification of lettuce bacterial soft rot resistance. A total of 50 lettuce varieties were evaluated and indicated that, ten of which showed high resistance, such as Yusheng 4, Xiangsheng 2 and Italian lettuce; 31 varieties (Beisheng 2, Hamburg, Radar ect.) showed moderate resistance, and the other 9 varieties were susceptible to bacterial soft rot; There were no immune or highly susceptible materials. Different types of lettuce germplasm had various degrees of disease resistance. Compared with loose-leaf lettuce, crisphead and romaine lettuce possessed more resistant resources, and most of purple lettuces were more resistant than green lettuce to bacterial soft rot.

Key words: Lettuce, Bacterial soft rot, Disease resistance evaluation

CLC Number: 

• S436.36