Section 6
Chapter 5,264

Effect of potassium status of potassium rubidium uptake and transport in sunflower helianthus annuus cultivar halcon

D.L.G.ardia M.D.; Fournier, J.M.; Benlloch, M.

Physiologia Plantarum 63(2): 176-180


ISSN/ISBN: 0031-9317
DOI: 10.1111/j.1399-3054.1985.tb01899.x
Accession: 005263204

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Young sunflower plants, grown in nutrient solution at 2 K+ levels (0.25 and 2.5 mM) were used to study the effect of K+ content in the root on uptake and transport of K+ to the exuding stream of decapitated plants. Roots of plants grown in low K+ gave higher exudation flux, higher K+ concentration in exudate and higher K+ flux than high K+ roots. After 6 h of uptake the K+ flux in low K+ roots was .apprx. 3 times that in high K+ roots. When the roots were kept in a nutrient solution in which Rb+ replaced K+, low K+ roots exuded much more Rb+ than K+ after the first 2 h, whereas high K+ roots exuded about similar amounts of K+ and Rb+. In intact plants grown at 3 different K+ levels (0.1, 1.0 and 10.0 mM), there was an inverse relationship between the K+ level in the nutrient solution and the Rb+ accumulated in the roots or transported to the shoot. The transport of ions from xylem parenchyma to stele apoplast may be controlled by ions coming down from the shoot in sieve tubes.

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