Abstract: The allotetraploid interspecific hybrid of 4x flowering Chinese cabbage（2n=4x=40）× 4x kailan （2n=4x=36） was obtained by ovary culture. The results showed that the most suitable medium for ovary culture of 4x flowering Chinese cabbage × 4x kailan was Nitsch medium supplemented with sucrose 70 g/L, agar 7 g/L, vitamin B₁ 0.5 mg/L, vitamin B₆ 0.5 mg/L, biotin 0.01 mg/L, 6-BA 0.5 mg/L, IAA 0.1 mg/L, pH 5.8, and the best culture stage was 7 d after pollination. The cytological identification showed that chromosome number of the allotetraploid was 2n=4x=38. The amount of DNA by flow cytometry showed that DNA relative content of the allotetraploid was twice of that of its diploid presents. The morphlogical observation showed that the characters, such as anthesis, leaf shape and colour, flower size and colour, of the allotetraploid hybrid were between of its parent species.

Key words: Flowering Chinese cabbage, Kailan, Allotetraploid