Effects of Light Environment on Recovery from Harvest and Antibacterial Properties of Oshá Ligusticum porteri (Apiaceae)1

Abstract

Wild-harvested medicinal plants collected from different light environments may show differential recovery from harvest. Also, plants growing in open and shaded habitats may allocate resources differently to defense. Since defensive compounds are biologically active, this difference may lead to variation in medicinal properties. We designed an experiment to test the hypothesis that light environment will affect both the ability of populations to recover from harvest and the medicinal properties of Ligusticum porteri (Apiaceae). L. porteri is a wild-harvested plant found in both high-elevation meadows and forest understories. Surveys in 2010 documented differences in population structure between light environments, with fewer flowering stalks in the understory. In 2012, we harvested plants in plots within five sites across varying light (PAR) levels at three different intensities: 0%, 50%, and 100% of ramets collected. We monitored regrowth in these plots over two years. We also tested the medicinal properties of methanol root extracts of L. porteri from the harvested plots using disc-diffusion assays. We found that L. porteri was able to regrow leaves following even intensive harvest (100%), although these were smaller than in control (0%) plots. Harvest significantly reduced the number of flowering stalks, changing population structure. While light did not impact the ability to regrow following harvest, it did influence antibacterial activity. The ability to inhibit Bacillus cereus decreased in extracts from plants harvested from high light environments, which follows plant defense theory. Altogether, harvest sustainability in L. porteri is equivocal among the light environments examined in this study, although some medicinal properties vary. L. porteri populations can recover from harvest through vegetative regrowth.