ISSN:
1573-5036
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary The effect of the valence of the associated cation on Cl−-uptake by excised barley roots grown in CaSO4 has been studied at 26°, 6° and 2°C. The uptake of Cl− relative to that of the associated cation was found to increase in the order: trivalent 〉 divalent 〉 monovalent. This was explained on the expected effect of the cation on the negative charge and potential of root surfaces. A lyotropic order was observed in case of monovalent cations, whereas divalent cations showed no such order. The order observed in Cl−-uptake from chloride solutions of monovalent cations is associated with the ability of the absorbed cation to remove Ca and Mg from the roots. Li+ behaved similar to divalent cations in affecting the relative Cl−-uptake from LiCl. As to the effect of temperature on the uptake of Cl− and associated cation, it appears that Cl− is not taken up to any great extent at 2°C whereas cations are still adsorbed at this low temperature. This has been explained on the assumption of the presence of negative adsorption spots on the root surface which can hold cations but not anions. It appears that Cl−-uptake by roots requires the expenditure of energy to overcome repulsion arising from the negative surface.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01377212
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