What is Plants Nutrition? Things you need to know 

The study about chemical, organic or inorganic elements and compounds present in the soil but necessary for metabolism, growth and proper development of the plant body, is called Plants Nutrition. Both plants and animals require minerals for their development. In its absence, the plants are unable to complete their normal life cycle. 

Criteria of Essentiality of an element in plants nutrition

According to scientist Arnon and Stout, an element would be essential when present following characteristics – 

• Deficiency of an element retards the natural growth of plants. 
• Directly involved with plant growth and metabolism. 
• A plant can not complete its normal life cycle without the presence of these elements. 
• One element can not perform a similar function of another element. 
• Deficiency of this element prevents vegetative and reproductive structures. 
• Very much important elements are N in protein and Mg in chlorophyll. 

Classification of Minerals 

Essential minerals for plants nutrition

Those elements are important for many physiological activities of the plant body and their deficiency creates prevention in growth and other biological activities, they are called essential elements. 

   Ex – Nitrogen (N), Phosphorus (P), Potassium (K), Magnesium (Mg), Calcium (Ca). 

Non-essential minerals for plants nutrition

These elements have no major rule in plant nutrition. 

   Ex – Aluminium (Al), Vanadium( Va). 

Toxic minerals for plants nutrition

Many toxic metals cause harmful activity in the plant body that creates many deficiency symptoms. 

   Ex – Arsenic (Ar). 

Macro and Micro Nutrients

Plant nutrition divided into 2 variety- 

Macro elements

 Nutrients that require a very large quantity in the plant body for normal growth and development, they are called Macroelements. Ex – carbon(C), Hydrogen (H), Oxygen (O) etc. 

Micro-elements

  Nutrients that require a smaller quantity in the plant body for growth and development these are called Microelements. Ex – Iron(Fe), Zink(Zn). 

General role of Essential Nutrients

1. Formation of protoplasm and cell wall: Essential elements help to construct the constituents of the cell wall and enter protoplasm and also biomolecule formation. Ex – Ca and Mg helps in middle lamella formation, Mg helps in chlorophyll formation, and N is very much essential for amino acid, protein, nucleic acid and also auxin, Cytokinin formation. 
2. Formation of energy-producing compounds: Mg is very much important element in chlorophyll formation. Chlorophyll helps in the Photosynthesis process where light energy is transferred into chemical energy. P helps in the formation of high energy molecules like ATP and GTP. 
3. Catalytic action: Many ions and elements show a catalytic reaction when they act as a cofactor and increase the enzyme reaction. Ex – Zink, magnesium, calcium and copper act as a metallic catalyst in many biochemical reactions. 
4. Regulation of cellular acidity or buffer action: Phosphate and Carbonate compound acts as a buffer and they prevent pH change of protoplasm. 
5. Influence of permeability: Sodium ion and Potassium ion increases the permeability of cell membranes but Calcium ion decreases the cell membranes permeability capacity. 
6. Osmotic potential: Several minerals present in cell sap in the organic or inorganic form that regulate the organic pressure of the cell If osmotic pressure is high turgor pressure is also high that helps to increase the absorbent quality of mineral elements by roots. Potassium ion helps this fact. 
7. Oxidation-reduction activity: Iron, copper etc have participated in the conductivity of electronics. 
8. Phloem transport: Boron and Potassium have actively functioned in the transportation system. 
9. Toxic effect: Certain elements like copper, manganese, and zinc show toxic reactions if their quantity increases in plant body or in the soil also. Another element like arsenic, nickel, also has a toxic effect when increasing their density in a small amount in the plants under specific conditions. 
10. Antagonistic effects: If the activity of any ion is prevented by another ion then it called its antagonistic effects. In the case of sodium and potassium, this type of effect can be found. 

Role and Deficiency symptoms of Macroelements

1. Nitrogen (N) 

Sources: Ammonium nitrate, Calcium nitrate, Potassium nitrate, nitric acid etc. 

Function: 

• The main element in protoplasm formation. 
• Present in many growth hormones like oxin, cytokinin etc. 
• It is a vital constituent of vitamin, nucleic acid, and chlorophyll formation. 

Deficiency symptoms:

• Deficiency of nitrogen leads to the complete suppression of flowering, fruiting 
• Leaves become a yellowish colour which is called chlorosis. 
• Development of anthocyanin pigmentation in stems. 

2. Phosphorus (P)

Sources: Phosphoric acid, Monopotassium phosphate. 

Function:

• It is used in several energy transfer molecules in the plants. 
• Helps in fruit ripening and division of meristematic tissue. 
• Helps in formation of the phospholipid, an important element of the cell wall. 

Deficiency symptoms:

• Deficiency of this element leads to the premature fall of leaves and they turn dark green in colour. 
• Show necrotic spots in leaves, fruits etc. 
• Return normal growth and development. 

3. Sulphur (S)

Sources: Magnesium sulphate, Potassium magnesium sulphate, sulphuric acid. 

Function:

• It is one type of sulphur-containing amino acids such as methionine and cysteine. 
• Helps in the formation of disulphide bonding into protein molecules. 
• Actively participate in the nitrogen fixation process. 

Deficiency symptoms:

• New leaves turn yellowish, which is called chlorosis. 
• Stems become very much rigid for excessive sclerenchyma. 

4. Calcium (Ca) 

Sources: Calcium nitrate, Calcium chloride. 

Function:

• Essential in cell wall development in the form of calcium pectate. 
• In certain enzymatic reactions, it acts as a cofactor. 

Deficiency symptoms:

• Tip portions of leaves are not equal, become curly and then damaged, this is called wither tip. 
• Shows abnormality in the cell division. 
• Retard the growth of stem and root. 

5. Magnesium (Mg)

Sources: Magnesium sulphate, Potassium magnesium sulphate.

Function: 

• Vital role in plant cells since it appears in the centre of the chlorophyll molecule. 
• It acts as a cofactor of enzymes (Hexokinase). 
• Helps in lipid and fat metabolism. 

Deficiency symptoms:

• There is a yellowish spot in the old leaves. 
• Chlorosis occurred. 
• Photosynthesis becomes affected if the quantity of magnesium is very high in leaves. 

6. Potassium ( K) 

Sources: Potassium sulphate, Potassium nitrate. 

Function:

• Act as an activator in many enzymatic reactions. 
• Helps in formation of guard cells around the stomata, thus it controls the opening and closing of the stomata. 
• Control osmotic pressure. 

Deficiency symptoms:

• Found yellowish margin in mature leaves. 
• The length between nodes and internodes are decreased. 

Role and Deficiency symptoms of Microelements

1. Iron (Fe) 

Source: Chelated iron ( EDTA, DTPA). 

Function:

• The main element in nitrogen-fixing enzyme Nitrogenase. 
• Actively functioned in chlorophyll synthesis. 

Deficiency symptoms:

• Prevent chloroplast formation. 

• Show interveinal chlorosis. 

2. Manganese (Mn) 

Source: Manganese chloride, Manganese sulphate. 

Function:

• Act as a cofactor of enzymes like carboxylase, dehydrogenase, peroxidase etc. 
• Helps in chlorophyll synthesis. 

Deficiency symptoms:

• Grey spots found in leaves. 
• Show interveinal chlorosis 

3. Molybdenum (Mb)

Source: Ammonium molybdate, Sodium molybdate. 

Function:

• An important element of the nitrogenase enzyme. 
• Actively participate in nitrogen fixation. 

Deficiency symptoms:

• Shows whiptail in cauliflower and a yellowish spot in citrus. 
• Show interveinal chlorosis. 

4. Boron (B) 

Source: Sodium borate, Boric acid. 

Function:

• Helps in lignin production that is the main element of cell walls. 
• Active role in pollen formation. 

Deficiency symptoms:

• Show top sickness in tobacco and heart rot in beat. 

• The premature death of terminal bud. 

5. Copper (Cu)

Source: Copper sulphate, Cupric chloride. 

Function:

• An important element in many enzymes. 
• Control carbohydrates and nitrogen balance. 
• Act as a cofactor of enzymes like Phenolase and Asborbic oxidase. 

Deficiency symptoms:

• Show dead leaves and withered margin, starting from top to the bottom portion, that is called Dieback. 
• Decrease absorption capacity of carbon dioxide. 

6. Zinc (Zn)

Source: Zinc sulphate. 

Function:

• Helps in synthesis of plant growth regulator, indoleacetic acid.
• Helps in cytochrome synthesis and chlorophyll synthesis. 

Deficiency symptoms:

• Prevent normal growth and development. 
• Plants become rosette forms because the duration of the node and internode decreases. 

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