Abstract: Using hypocotyl of sterile celery seedling, induce conditions of embryonic callus were studied in this paper. Embryoid was obtained from the embryonic callus, and effect of Co²⁺ on formation of the embryoid and levels of endogenous IAA and ABA were studied. The results showed that the competence of formation of the callus and embryonic callus from hypocotyl of celery decreased with its relative position from leaf end to apex of root. 2, 4-D was favored to induction of embryonic callus. There was no significant effect of casein hydrolysate on expression of embryonic competence in celery. Endogenous levels of IAA and ABA in the cultures were reduced and induce rates of embryoid was increased by Co²⁺ during embryoid formation of celery. There were one peak value of IAA levels and two peak values of ABA levels in the culture of control groups. The change of ABA levels in the culture of treatment groups was simular to control, but there was not peak value of IAA in the treatment. It was infered that there were difference effects Co²⁺ inhibitation mechanism on between IAA and ABA in the formation of celery embryoid.

Key words: Celery, Embryonic callus, Formation of embryoid, Co²⁺, IAA, ABA