Аннотация:A solid‐phase enzyme‐immunoassay for abscisic acid and abscisic acid conjugates in fmol amounts (detection limit ca 50–60 fmol) has been developed. Only little procedural effort is required for the assay which can be completed within 6 h. With this method, abscisic acid was detected in a range of heterotrophically growing plant suspension cultures. In addition, abscisic acid‐glucosyl ester was identified in a Lonicera prolifera Rehd. tissue culture. In this tissue, the level of free abscisic acid reaches ca 2 × 10 −6 M in the late log‐phase of growth.