Abstract: Receptacles with ovary and pedicel used as explants, the regeneration systems of different fertility explants of genic recessive male sterility A/B lines in Chinese cabbage-pak-choi (Brassica campestris L. ssp. chinensis Makino) were compared. Moreover, itwas analysed that the effect on different fertility explants regeneration of interaction between endogenous hormone of exp lant itself and exogenous app lication. Results showed that the best exogenous NAA concentrations for adventitious shoots induction of the sterile and the fertile explantswere 0.2 mg·L ^{- 1} and 0.1 mg·L ^{- 1} , respectively. With the optimal NAA concentrations, shoot induction rate of sterile explants was not significantly affected by 6-BA, however, that of fertile showed erratically change with different 62BA concentration. The result of endogenous hormone determination showed that the endogenous contents of GA₃ , IAA and ZT in fertile explants were 37.8% , 28.0% and 224.9% higher than in that of the fertile, but ABA content is sterile exp lantswas 20;4% higher than that of the fertile. The shoots regenerated from this kind of floral explants showed high frequency bolting rate without subculture or with few times subculture. But with the times of subculture increasing, the tendency of rep roductive growth declined whereas the rooting rate enhanced significantly.

Key words: Chinese cabbage-pak-choi, Brassica campestris ssp. chinensis, Explant, Male sterile, Adventitious shoot induction, Culture medium