Foliar application of nitrate or ammonium as sole nitrogen supply in Ricinus communis - II. The flows of cations, chloride and abscisic acid

Citation
Ad. Peuke et al., Foliar application of nitrate or ammonium as sole nitrogen supply in Ricinus communis - II. The flows of cations, chloride and abscisic acid, NEW PHYTOL, 140(4), 1998, pp. 625-636
Citations number
39
Categorie Soggetti
Plant Sciences
Journal title
NEW PHYTOLOGIST
ISSN journal
0028646X → ACNP
Volume
140
Issue
4
Year of publication
1998
Pages
625 - 636
Database
ISI
SICI code
0028-646X(199812)140:4<625:FAONOA>2.0.ZU;2-M
Abstract
Following a precultivation with pedospheric nitrogen nutrition, Ricinus pla nts were supplied with nitrogen solely by spraying nitrate or ammonium solu tion onto the leaves during the experimental period. The chemical compositi on of tissues, xylem and phloem exudates was determined and on the basis of the previously determined nitrogen flows (Peuke et al., New Phytologist (1 998), 138, 657-687) the flows of potassium, sodium, magnesium, calcium, chl oride and ABA were modelled. These data, which permit quantification of net -uptake, transport in xylem and phloem, and utilization in shoot and root, were compared with results obtained in plants with pedospherically-supplied nitrate or ammonium and data in the literature. Although the overall effec ts on the chemical composition of supplying ammonium to the leaves were not as pronounced as in pedospherically supplied plants, there were some typic al responses of plants fed with ammonium (ammonium syndrome). In particular , in ammonium-sprayed plants uptake and transport of magnesium decreased an d chloride uptake was increased compared with nitrate-sprayed plants. Furth ermore, acropetal ABA transport in the xylem in ammonium-sprayed Ricinus wa s threefold higher than in nitrate-sprayed plants. Additionally, concentrat ions of anions were more or less increased in tissues, particularly in the roots, and transport fluids. The overall signal from ammonium-sprayed leave s without a direct effect of ammonium ions on uptake and transport systems in the root is discussed.