| Abstrakt: |
A model describing the transport of elements through the xylem vessels into the leaf of a red cherry tomato (Lycopersicon esculentum Mill cv. Tiny Tim) in a non-steady state situation is presented. The model describes the upward movement of ions as a mass-flow of the xylem fluid with dissolved elements, with lateral ion escape represented by a first-order process. The model is fitted to data obtained in an experiment in which 15 elements were applied in a solution to a cut stem part with attached leaf and were measured simultaneously by gamma-ray spectroscopy. The model is in good agreement with the transport into the leaf of K+, Na+, Rb+, Cs+, Yb3+, Sm3+, Zn2+, Co2+, Cu2+, Sb(SO4)2-, AsO43-, WO42- and Mo7O246-. Only indirect data could be obtained for Cd2+ and La3+ because of their apparently high affinity for charged sites in the cell walls and high escape constant, respectively. The escape constants were relatively low for all anions, probably due to the presence of a large number of negative charges in the cell walls. [ABSTRACT FROM AUTHOR] |
Plný text