Einfluß von Chelatoren auf die Calcium-Verlagerung im Sproß höherer Pflanzen

Influence of chelating agents on calcium translocation in the shoots of higher plants Using 28-day-old plants and shoots of bush beans as well as isolated haulms of barley taken from the field 24-hour experiments were carried out to investigate how equimolar additions of the chelating agents Na₂H₂ EDTA (EDTA) or citric acid to the ⁴⁵CaCl₂ uptake solution (0.5–1.0 mM/l) influenced Ca-translocation in the shoot. The following results were obtained:

• 1 If Ca²⁺ was taken up by the intact root system, equimolar additions of EDTA to the CaCl₂-uptake solution reduced Ca-uptake, and therefore the translocation of Ca to and within the shoot was also lowered.
• 2 Chelating agents favoured Ca-translocation in the shoots only when Ca-uptake as a chelate by the plasmalemma of the root cells was prevented using DNP or when the roots were by-passed by injecting chelates or by removing the roots themselves.
• 3 Additions of MgCl₂ (0.5 mM/l) or DNP (10^?5-10^?4 M/l) to the ⁴⁵CaCl₂ uptake solution (0.5 mM/l) of isolated shoots reduced the favourable effect of equimolar EDTA-levels on Ca-translocation because Mg²⁺ and DNP themselves increased Ca-translocation.
• 4 From the effects of Mg²⁺ and DNP it was concluded that the favourable influence of chelating agents on Ca-translocation within the shoot can be explained on the one hand by the reduction in adsorption of Ca²⁺ on negatively charged cell walls of the xylem and on the other hand by the diminished accumulation and precipitation of Ca in the xylem-surrounding tissue.
• 5 On the basis of the results obtained here, stem injections of chelating agents or treatments which influence the content of native chelating agents in the plants appear to be possible starting points for the improvement of Ca-translocation within the shoot.