What are the Macro and Micro elements needed by plants?

Aug 09, 2022, 16:45 IST

Macro elements and Micro elements

Essential elements occur in different proportions in the plants. They are differentiated into two categories macro elements and micro elements.

The terms major, minor and trace elements are generally reserved for elements involved in animal nutrition. For More Biology Doubts visit main page of Physics Wallah .

(i) Macro elements (Macro nutrients)

• They are those essential elements which are present in easily detectable quantities atleast one milligram per gram of dry matter. Macro elements are usually involved in the synthesis of organic molecules and development of osmotic potential. They are nine in number C, H, N, P, K, S, Mg and Ca. 96% of the dry matter is formed of Carbon, Hydrogen and Oxygen.

• On fresh weight basis, oxygen is the most abundant element in plant body as well as other organisms.

• On dry weight basis, it is almost as abundant as carbon.

• Of the nonessential functional elements, silicon and sodium often occur in the range of macroelements.

• Iron occurs in the concentration of less than 1mg/g. However its essentiality was discovered along with other macro elements long before microelements were found to be required. Therefore, it is often regarded to be macroelement.

(ii) Microelements (Micronutrients)

• They are those essential elements which are required by plants in traces only, equal or less than 0.1 mg/g of dry matter. Their essentiality came to be known only when extra pure salts were used in culture experiments.

• Microelements are mostly involved in the functioning of enzymes, as cofactors or metal activators. They are eight in number – Fe, Zn, Mn, B, Cu, Mo, Cl and Ni. Non essential functional elements which belong to the category of micro elements are Cobalt, Vanadium and Aluminium.