Question

A micronutrient causes toxicity when:

• A. Its concentration is higher than required by the plant
• B. Its concentration in a tissue reduces the dry weight of the tissue by about 10%
• C. Its concentration results in symptoms like necrosis or chlorosis
• D. Its concentration in a tissue inhibits the action of certain enzymes

Answer 1

The correct option is B

Its concentration in a tissue reduces the dry weight of the tissue by about 10%

All the options given here are suitable for defining the condition of mineral toxicity, but a quantifiable criterion is always the best way to define toxicity since the minerals are required in small concentrations for the normal functioning of the plant tissues. Thus, when the concentration of a certain micronutrient, in a tissue, reduces the dry weight of the tissue by about 10%, it is said to have caused toxicity.