GROWTH-REGULATORY RESPONSE OF PARTHENIN AND ITS DERIVATIVES

Parthenin and its pyrolysed and photo-derivatives exhibit a range of g rowth regulatory effects depending on their structure. At 5 mg L-1 (th e lowest concentration used) the activity of all parthenin derivatives was greater than that of indole-3-acetic acid (IAA) in biotests based on growth and morphogenetic response of hypocotyl cuttings of Phaseol us aureus. Seedling growth was greatly enhanced by pyrolysed parthenin whereas parthenin and photo-parthenin promoted rooting of the hypocot yl cuttings. Structural changes in parthenin resulting from chemical a nd photochemical reactions, therefore, alter its growth regulatory act ion.