1State Key Laboratory of Vegetable Biobreeding，The Institute of Vegetables and Flowers，Chinese Academy of Agricultural Sciences，Beijing 100081，China；2Ulanqab City Science and Technology Commissioner Entrepreneurship Federation，Ulanqab 234000，Inner Mongolia，China
Abstract：Alternaria leaf blight （ALB） is one of the most common and destructive diseases in carrot．This study compared the effects of different inoculum concentrations and seedling ages on the disease index of ALB，and selected the most suitable conditions for artificial inoculation identification，and then establish a set of accurate and stable artificial inoculation identification system for ALB，the results show that the bacterial liquid concentration of 1 × 104 spores · mL-1，inoculation seedling age of 8 true leaves is the most suitable artificial inoculation identification conditions．This identification system was utilized to identify 94 carrot germplasm resources for ALB resistance，and one resistant material（DI = 28.4）was selected，an important resistance source material for carrot breeding．
