Nitrogen Dioxide at an Ambient Level Improves the Capability of Kenaf (Hibiscus Cannabinus) to Decontaminate Cadmium

Abstract

As reported previously, atmospheric nitrogen dioxide (NO₂) at an ambient level increased plant size and the contents of cell constituents. We investigated this effect of atmospheric NO₂ on decontamination of cadmium (Cd) by kenaf (Hibiscus cannabinus). Seventeen-day-old seedlings of kenaf were grown in air either with NO₂ or without NO₂. (Plants were exposed to 100 ± 50 ppb NO₂ for 10 d under irrigation of 0.1% Hyponex supplemented with 20 μM CdCl_2.) Plants were then harvested and the biomass of stems, leaves, and roots, as well as the content of Cd in the organs, was determined. The stem and root biomass per plant were 1.25–1.27-fold greater in +NO₂ plants than in –NO₂ plants. The Cd content per stem was more than 30% greater in +NO₂ plants than in –NO₂ plants.

KEY WORDS:

• air pollution
• heavy metal contamination
• plant vitalization

ACKNOWLEDGMENT

This work was supported in part by a Grant-in-Aid for Scientific Research (18770037) from the Japan Society for the Promotion of Science and by grants from the Shimadzu Science Foundation.