Ecotoxicological effects of cadmium on three ornamental plants

Abstract

Ecotoxicological effects of cadmium (Cd) on three ornamental plants African marigold ( Tagetes erecta), scarlet sage ( Salvia splendens) and sweet hibiscus ( Abelmoschus manihot) were investigated. Seeds of these plants were exposed to five different concentrations of Cd (0–50 mg l −1). Ecotoxicological indexes based on inhibition rate (IC) of seed germination, root and shoot elongation, biomass (fresh weight and dry weight), as well as IC 50 (Cd concentration when 50% plants show inhibition) and tolerance indexes (the ratio of maximum root length in an experimental group to that in a control group) were determined. The results indicated that Cd had little effects ( p > 0.05) on seed germination of the three plants and shoot elongation of scarlet sage ( S. splendens). Cadmium had significant ( p < 0.05) inhibitory effects on root elongation of the three plants and shoot elongation of African marigold ( T. erecta). The fresh weight biomass of scarlet sage ( S. splendens) was most sensitive to Cd, while that of sweet hibiscus ( A. manihot) was least sensitive. On a dry weight basis, African marigold ( T. erecta) was the least sensitive, and scarlet sage ( S. splendens) was the most sensitive to Cd. Based on IC 50 of seed germination, sweet hibiscus ( A. manihot) was the most insensitive plant with an IC 50 value as high as 428.0 g l −1. According to Cd-tolerance indexes under the same Cd concentration, sweet hibiscus ( A. manihot) was the most tolerant plant whereas scarlet sage ( S. splendens) was the most sensitive one.