Any material ion concentration in tissues that reduces the dry weight of tissues by about 10 percent is considered toxic. Many a time, excess of an element may inhibit the uptake of another element. For example the Mn toxicity is the appearence of brown spots surrounded by chlorotic veins. Mn in excess, competes with iron and Mg for uptake and with Magnesium for binding with enzymes. Manganese also inhibits calcium translocation in the ***** apex. Therefore excess of manganese may infact, induce deficiencies of iron, magnesium and calcium.
