Phytotoxicity assay of crop plants to phenanthrene and pyrene contaminants in acidic soil.

Four selected plants (corn, groundnut, cow pea, and mungbean) were tested for their ability to germinate and grow in an acidic soil contaminated with phenanthrene or pyrene, two typical polycyclic aromatic hydrocarbons (PAHs). The growth of corn root was the least sensitive to, but its germination rate was the lowest in the presence of, contaminants. Among the legumes, the growth of groundnut root was better than others. Corn and groundnut were selected to further test their ability to tolerate a mixture of phenanthrene and pyrene in the acidic soil. The presence of both PAHs led to a greater decrease in the lengths of shoot and root of groundnut than phenanthrene or pyrene alone, but the lengths of shoot and root of corn were decreased to a similar extent as when phenanthrene or pyrene was present alone. The growth of corn root was also better than that of groundnut root when they were grown in oil-contaminated soil. Based on these results, we conclude that corn is the most suitable to be grown in PAH-contaminated acidic soil.