1Central Potato Research Institute, Simla, (H.P.)-171001.
Percentage germination of seeds of mustard (Brassica juncea L.) in the dark, on paper moistened with (±)-abscisic acid (ABA) solutions, varied linearly with log ABA concentration in the range 10−6 to 10−5 M. The response was not sensitive to the presence, in the test solution, of gibberellic acid, indole acetic acid, or kinetin at concentrations of the same order of magnitude as that of the ABA present. When peels of dormant potato tubers were extracted and the extracts subjected to the bioassay after thin layer chromatography their ABA content was found to be of the order of 0.1 micro g per g fresh weight of peel. The ABA accounted for at least half of the growth inhibitory activity of the crude extract. The presence of at least other inhibitor was indicated.
