Relationship between Cadmium Uptake and Transpiration

Helianum annuus L., Artemisia scoparia, Zinnia elegans and Tagetes patula L. were introduced to study cadmium (Cd) accumulation. Cd accumulation in different organs and its relationship with transpiration were investigated in aqueous Hoagland medium contained 0.1 mgL^-1 cadmium. The results showed that younger leaves exhibited higher Cd concentration than older leaves in all the plants. The efficiency of Cd shoot uptake was very different from each other in the four experimental plants. For Helianum annuus L., the efficiency was below 1; for Artemisia scoparia, it was about 1; for Zinnia elegans and Tagetes patula L., it was larger than 1. The results suggested that the contribution of transpiration to Cd shoot accumulation was different in different plants. Probably shoot Cd accumulation was not only dependent on transpiration in some plants. Water transport in Tagetes erecta L. was studied using Hydrogen stable isotope technology, there was no significant difference in water need between younger leaves and older. Thus, it is assumed that Cd uptake is not totally driven by transpiration.