Question

What are essential elements for plants?

Give the criteria of essentiality?

How are minerals classified depending upon the amount in which they are needed by the plants?

Answer 1

a. Essential elements:

Elements without which plants cannot survive and complete their life cycle are called essential elements. Deficiency of these elements brings about morphological changes.

b. Criteria for essentiality:

Criteria for essentiality of elements are as follows:-

● The element should play a vital role in the growth and reproduction: Life cycle of plants will not get completed without that particular element.

● Functionally the element should be unique: It should perform a specific function which cannot be done by other elements.

● Elements must be directly involved in metabolism in the plants: It should be involved in various anabolic and catabolic reactions involved in life processes.


c. Macroelements and microelements:

Essential elements are broadly categorised into two types depending on their requirements by the plants:

● Macronutrients: Required in excess of 10 mmol Kg–1 of dry matter. These include carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), sulphur (S), potassium (K), calcium (Ca), magnesium (Mg).

● Micronutrients: Required in less than 10 mmol Kg–1 of dry matter. These include iron (Fe), manganese (Mn), copper (Cu), molybdenum (Mo), zinc (Zn), boron (B), chlorine (Cl), nickel (Ni).