Abstract: Four Chinese cabbage varieties of different resistances to black spot were studied. Chemical compositions of leaf surface rinses from four Chinese cabbage varieties were identified roughly by gas chromatography coupled with mass spectrometry (GC/MS). Antifungal activities of the leaf surface rinses against Alternaria brassicae spores germination were investigated with the spore suspension method. The results showed that spores germination inhibition of the four leaf surface rinses against Alternaria brassicae could be arranged as Piao er bai＞Tian cui lv＞You zao si hao＞83-1, when the concentration above 10 µL. And there were significant difference among the four Chinese cabbage rinses. 2,2,4,6,6-Pentamethylheptane was the largest content compound (up to 17.15% of total chemical composition) in the Tian cui lv rinse. (E)-3-Hexen-1-ol was the largest content compound in the Piao er bai rinse, You zao si hao rinse, and 83-1 rinse and the contents were up to 15.76%, 10.87%, 7.21% of total chemical composition, respectively. The compounds 2,4,6,8-Tetramethyl-1-und-ecen and 2,4,6-Tritert-butyl-4-methyl-2,5-cyclohexadien-1-one were only detected in 83-1 rinse which was a most susceptible variety among the four Chinese cabbages. Based on the results, the four compounds, 2,2,4,6,6-Pentamethylheptane, (E)-3-Hexen-1-ol, 2,4,6,8-Tetramethyl-1-und-ecen and 2,4,6-Tritert-butyl-4- methyl-2,5-cyclohexadien-1-one, could be key compounds which showed some affection for Alternaria brassicae spore germination on Chinese cabbage leaves.

Key words: Chinese cabbage, leaf surface rinses, volatile organic compounds, Alternaria brassicae, GC-MS