Plant Physiology - Musienko M. M. 2001

Plant Root Nutrition
Ion Interactions in Plants

Obtaining high crop yields with superior product quality depends not only on the absolute amount of nutrients available, but also on the balanced ratios of mineral elements. When the soil contains a sufficient and properly balanced supply of nutrients, its overall reserves ensure high plant productivity.

The phenomena of elemental interaction—antagonism and synergism—are widespread in mineral Nutrition. Antagonism is the suppression of The Effect of one ion on the plant Organism by another, whereas synergism, conversely, is the enhancement of one ion's effect by another. Classic Examples of antagonism have long been known, such as between potassium and calcium, sodium and potassium, ammonium and potassium, as well as various divalent cations. It is well established that without boron, plants lose The ability to assimilate adequate amounts of calcium. In the presence of boron, the toxicity of other salts is mitigated, and their negative effects can be counteracted by calcium. A close interdependence also exists between the actions of molybdenum and phosphorus: as the concentration of phosphorus in the solution increases, the uptake of molybdenum by the plant likewise increases.

Previously, the causes of antagonism were attributed solely to the opposing effects of ions on the viscosity and permeability of the protoplasm. However, the manifestations of antagonism are diverse, and its instances are numerous: plants grown in a medium rich in potassium and phosphorus alongside a high dose of iron suffer from phosphorus deficiency; molybdenum inhibits the uptake of iron and slows its translocation to the upper PARTS OF THE plant. In plants supplied with moderate doses of iron and potassium, a high concentration of phosphorus in the environment leads to The Development of apical chlorosis and symptoms of potassium deficiency in older leaves.

It has been established that antagonist ions not only exert opposing effects on the PHYSICOCHEMICAL PROPERTIES OF protoplasm and specific metabolic pathways, but also compete for incorporation into organic complexes and Enzymatic Catalysis. Understanding the causes of ion antagonism remains one of the fundamental issues in The Theory of mineral nutrition.