Feverfew [Tanacetum parthenium (L.) Schultz-Bip.] is a strongly aromatic medicinal plant, whose active principle is the sesquiterpene lactone parthenolide. Irradiance ranks among the most important factors that affect growth of medicinal plants. The effect of three irradiance levels (730, 523 and 382 µmol of fotons m-2 s-1) were assessed on feverfew plants height, leaf area, and leaf number, as well as on the contents of sugar, starch, and parthenolide. Plants grew on full sunshine and under 30 and 50% of irradiance reduction, for 105 days. Irradiance was controlled by shadowing plants with a black polyethylene screen. Reduction on irradiance increased plant height and total leaf area, but had no effect on leaf number. A reduction in sugar and starch contents in association with shadowing was observed. Nevertheless, shadowing did not affect significantly the parthenolide content.
Tanacetum parthenium; shadowing; medicinal plants; soluble sugars; starch; parthenolide
