Question

Can the knowledge about toxicity of micronutrients be of some importance to a farmer? a gardener? or even for you in your kitchen-garden?

Answer 1

1) Introduction to micronutrients:
Micronutrients are those which are present in very small amounts in the tissues of the plants. They are present in amounts less than 10 mmol $K{g}^{-1}$ of dry matter. Copper, iron, manganese, molybdenum, zinc, boron, chlorine and nickel are the eight micronutrients.

2) Toxicity of micronutrients:
Since micronutrients are required in very small amounts, a moderate increase above their critical concentration in plants leads to toxicity. Toxic effects can be due to:

• Excess of a nutrient/ micronutrient.
• Interference in the absorption and functioning of other essential elements due to an excess element.

3) Utilisation of knowledge of toxicity of micronutrients Observing toxicity symptoms helps to get an idea of the nutrient in excess. This will help us in the following aspects:

• Make a balance of all the essential elements in the optimum amount in the manure/ fertiliser before application.
• Use an appropriate chelating agent to reduce the concentration of the toxic element.
• Identify the element(s) whose uptake is hampered due to interference of the toxic element.
• Adjust the proportion of those elements (whose uptake gets compromised due to excess of an element) in the fertiliser to avoid deficiency symptoms. These will in turn help to increase the yield.