Iron-nutritional aspects of the ionic balance of plants

Summary The effect of iron on the ionic balance of several plant species and cultivars was studied. Those plants which normally excrete relatively low amounts of hydroxyl ions respond to iron stress by lowering the pH of the nutrient medium and decreasing anion uptake. These plants may be considered as being Fe efficient. Plants which normally excrete relatively high amounts of hydroxyl ions and which continue to increase the pH of a nutrient medium when under iron stress may be considered as Fe inefficient.Iron deficiency tends to increase carboxylate accumulation and to decrease anion uptake. When cation uptake is depressed by iron deficiency this is mainly a non specific depression of potassium uptake, on the other hand when iron stress stimulates cation uptake this is mainly due to a specific stimulation of the divalent cations Ca and Mg.Additional key words: Iron, efficiency of uptake, ionic balance, hydroxyl and hydrogen ion excretion.