Copper Accumulation in Citrus Roots and Desorption with Acid1
- E. A. Brams and
- J. G. A. Fiskell2
Root accumulation of 04Cu from labelled Cu(NO3)2 in intact ‘Mandarin Orange’ (Citrus reticulata) seedlings had a constant rate for the first 15 min and then became curvilinear for periods from 15 to 180 min, when the ambient solution contained 0.6 ppm Cu. Over a 60-min contact time uptake of Cu was linear for ambient Cu concentration range from 0.3 to 1.2 ppm. Extraction of 64Cu in roots by 0.1N HCl was linearly proportional to total root Cu and was 95% complete after 28 min. Colloidal phosphate reduced 64Cu accumulation in the roots by 12%. In roots of ‘Sour Orange’ (C. aurantium) seedlings grown in solution culture and in groves Cu was located in thin sections by ferrocyanide staining. Concentration of Cu occurred in the exodermis, endodermis, and pericycle cells. Electromicrographs of citrus roots suffering from Cu toxicity showed irregular deformation of cell walls in xylem vessels. In such cases roots became club shaped as root elongation ceased. Reactions of Cu with protein are suggested as mechanisms for Cu accumulation in roots.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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