Authors:J. Marešová, L. Remenárová, M. Horník, M. Pipíška, J. Augustín, and J. Lesný
The aim of this paper was to obtain quantitative data of foliar uptake kinetics and long distance transport of zinc in tobacco
(Nicotiana tabacum L.) and hop (Humulus lupulus L.) plants. Zinc was used as a model of microelement and toxic metal, tobacco and hop as a representatives of agriculturally
important plants. A tip of leaf blade was immersed in the solution spiked with 65ZnCl2 and foliar uptake and translocation to other parts of the plant grown in nutrient solution was measured by gamma-spectrometry
and autoradiography. We found that foliar zinc uptake by both plants is dependent on the initial metal concentration within
the range C0 = 10–100 μmol dm−3 ZnCl2. Zinc is immobilized mainly in immersed part of the contact leaf and only <1% is transported to non-immersed parts of the
leaf. At C0 = 0.1 mmol dm−3 ZnCl2 concentrations >2.5 mg/g Zn and 4.8 mg/g Zn (dry wt.) in immersed part of tobacco and hop leaf plant, respectively were found
after 5 days of exposure. Low mobility of zinc entering the plant via the leaf surface can be attributed to the immobilization
of zinc into Zn–ligand complexes with high stability constants log K at pH 6.0–8.0, such as the reaction products of Zn2+ ions with citric acid, histidine or phosphates. Zinc can be extracted from dried leaves by the solutions of inorganic salts,
carboxylic acids, amino acids and synthetic complexing ligands such as EDTA. Anionic (SDS) and non-ionic (Tween 40) surfactants
causes the decrease of the Zn foliar uptake, but not translocation of Zn from the contact leaf area. Obtained data are discussed
from the point of view of possible limited efficiency of liquid formulations designed for practical applications as Zn foliar
Authors:J. Tent, M. Vidal, M. Llauradó, G. Rauret, J. Real, and P. Mischler
In order to study the foliar uptake of radionuclides deposited from an aerosol released in an accidental situation, lettuce plants were contaminated with an aerosol containing85Sr,134Cs and110mAg isotopes. The methodology chosen to carry out this study is based on a sequential extraction scheme using water, to evaluate the fraction possibly removed by rain or by washing, and an organic solvent, to distinguish between the fraction adhering to the cuticle and the one incorporated in the leaves. Two procedures are compared. Moreover, the different behavior of the radionuclides in their incorporation into the leaves is deduced from the results obtained.
Authors:J. Hattink, L. Weltje, H. Wolterbeek, and J. de Goeij
This study deals with the accumulation dynamics of the long-lived fission product technetium (99Tc) in duckweed. Duckweed serves as model for aquatic plants, because of its representative foliar uptake for 99Tc. This study shows that 99Tc is irreversibly accumulated and distributed over cytoplasm, chloroplasts and mitochondria. Autoradiography showed that 99Tc was not transported to new biomass. Irreversible storage of 99Tc in plant biomass means that steady-state situations cannot be interpreted as a balance between uptake and elimination of 99Tc, but that 99Tc continuously builds up in each single duckweed plant and overall Tc concentrations are averaged over new biomass.