Ion Competition in Manganese Uptake by Barley Plants

Abstract

Barley plants grown in Hoagland''s solution developed Mn toxicity symptoms in the leaves. The symptoms and Mn content of the tissues were reduced by increasing the macro-salt concentration in the nutrient solution. Using high single salts superimposed on a weak, balanced nutrient solution, it was found that Ca, Mg, or NH4 nitrates or sulfates lowered Mn uptake. Nitrate and sulfate of K and Mg phosphate had no effect. Plants grown in Ca or NH4 phosphate were lower in Mn, while K phosphate plants were higher than the control. Sodium salts behaved like those of K. Iron and H ions were the most effective in reducing Mn uptake.