The Effect of Thiuram on the Uptake of Lead and Copper by Melissa officinalis

In this work the effects of thiuram on the uptake of lead and copper by lemon balm (Melissa officinalis) were examined. Thiuram (tetramethylthiuram disulphide) is used as a fungicide to protect seeds, fruit, vegetables, ornamentals, turf crops, and herbs from a variety of fungal diseases. The preliminary investigation involved soil analyses (content of organic substances, acidity, total lead and copper, exchangeable and bioavailable forms, and mechanical analysis). The analysis showed that the soil used for the study was not contaminated with lead or copper. In this work the amounts of lead and copper were determined in roots and above-ground parts of: (a) plants untreated with thiuram; (b) plants which were sprayed with thiuram (3 mg per pot). It was found that thiuram influences the amount of lead and copper accumulated in the plant. The treatment of the plants with thiuram caused an increase of the content of lead in the roots (65, 75 days with fungicide) and reduction of lead in the above-ground parts. The addition of the fungicide caused a drop in the content of Cu in the roots, while the content of Cu in the above-ground parts decreased slightly (65, 75 days with fungicide).