ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of plant growth regulators on the growth and quality of Angelica dahurica var. formosana.</p><p><b>METHOD</b>Five plant growth regulators: chlormequat chloride (CCC), Mepiquat chloride (PIX), Gibberellic acid (GA3), Paclobutrazol (PP333) and Maleic Hydrazide (MH) were sprayed in rosette stage, the effects of these plant growth regulators (PGRs) on the growth, yield and quality of A. dahurica var. formosanaw were observed. The biological traits were first measured and then imperatorin and isoimperatorin contents in roots were determined by HPLC.</p><p><b>RESULT</b>Low concentration GA3 increased the yield while not influenced the premature bolting rate and the coumarin content.</p><p><b>CONCLUSION</b>Spraying of GA3 (30 mg x L(-1)) could guarantee the growth and development of A. dahurica var. formosana to have a higher yield and maintain the active ingredients content in the root as well.</p>