Influence of Moderate Cd and Pb Soil Pollution on Seed Development, Photosynthetic Performance and Foliar Accumulation in the Medicinal Plant Hypericum perforatum

Abstract

This study investigated whether moderate soil contamination by Cd and Pb may negatively affect seed germination, photosynthesis and foliar accumulation in the medicinal plant Hypericum perforatum. Seeds were incubated with Cd and Pb solutions of 10 and 100 µM, and two-month-old plants were watered weekly for three weeks with the same solutions. Control samples were treated with deionized water. The percentage of seed germination and seedling length, as well as chlorophyll content, chlorophyll fluorescence and foliar reflectance, were measured, along with the foliar Cd and Pb concentrations. The results indicated that seed germination is not affected, while seedling length is decreased by approximately 81% by high Cd levels. Cadmium was subjected to foliar translocation from the soil depending on the supplied concentration, thus causing reductions in the chlorophyll content (−24%). It is of interest that foliar Cd levels in Cd-treated plants were close to or above the limit for the European Pharmacopoeia. Negative effects of Pb were not detected, but accumulation and blockage of this metal at the root level, although not approached experimentally, cannot be ruled out.