the importance of macronutrients and micronutrients in plants

7/28/2019 The Importance of Macronutrients and Micronutrients in Plants

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Green plants are autotrophic organism that

functions as producers in ecosystems.

They are able to synthesise their ownnutrients by means of photosynthesis.

To carry out photosynthesis, they require raw

materials in the forms of inorganicsubstance, that is, carbon dioxide, water and

mineral nutrients.


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The elements required by plants can be

classified into macronutrients and

micronutrients based on the amount needed.

Macronutrients are elements required by

plants in large quantities

Micronutrients or trace elements areelements required by plants in traces or

small quantities.


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Macronutrients and micronutrients are

required to synthesise substances essential

for the healthy growth of plants.


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Macronutrients are :

Carbon (C)

Hydrogen (H)

Oxygen (O)

Nitrogen (N)

Phosphorus (P)

Potassium (K)

Calcium (Ca) Magnesium (Mg)

Sulphur (S)


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Carbon dioxide and water are sources of the

three important macronutrients, namely

carbon, hydrogen, and oxygen.

Other macronutrients required by plants are

obtained from the soil in the form of

inorganic ions.


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Carbon, hydrogen and oxygen are major

elements required by plants for the synthesis

of organic substance such as carbohydrates,

proteins, and lipids.

Besides the macronutrients, plants also

require other minerals even though in small

quantities.


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Micronutrients are

Boron (B)

Molybdenum (Mo)

Zinc (Zn) Manganese (Mn)

Copper (Cu)

Iron (Fe)

Chlorine (Cl)


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Micronutrients are required to activate some

enzymes involved in cellular metabolism such

as respiration. They may act as cofactors or

form part of coenzymes.

The absence of mineral nutrients will lead to

mineral deficiencies in plants.

Investigations on the effects of nutrient

deficiencies in plants can be done using

culture solution.


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A plant which grows in such a solution is then

compared to another plant which grows in a

complete Knops solution.


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Knops solution is a complete culture solution

and its contents are as follows

Calcium nitrate 0.8gPotassium nitrate 0.2g

Potassium dihydrogen phosphate 0.2g

Magnesium sulphate 0.2g

Iron (III) phosphate 0.2g

Distilled water 1 litre


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We can investigate whether a plant requires

a particular mineral element and the effect

of its deficiency by eliminating if rom Knops

solution.

For example, to study the effects of the

deficiency of magnesium, the magnesium

sulphate (MgSO4) in Knops solution isreplaced with potassium sulphate (K2SO4).


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Macronutrient Function Effects of deficiencies

Nitrogen (N) as a major component of

amino acids, nucleic acids

chlorophyll, enzymes and

coenzymes

promotes stem and leaf

growth

Chlorosis of leaves in

which synthesis of the

green pigment,

chlorophyll, is inhibited

resulting in a pale yellow

colouration

Stunted growth

Reduced yields

Phosphorus (P) As a component of nucleic

acids, adenosinetriphosphate (ATP) and

phospholipids in plasma

membrane

Needed for

photosynthesis and seed

germination

Poor root growth and

stunted growth of plant Formation of dark green

leaves with red or purple

spots on old ones


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Potassium (K) As a cofactor for

many enzymes

involved in protein

synthesis and

carbohydrate

metabolism

Involved in water

balance andregulates the

opening of stomata

Stunted growth

Yellowing of leaves

followed by dying of

leaf tips and edges

Premature death of

plants

Calcium (Ca) Needed for cell wall

formation

Regulates

movements of

substances across

cell membrane

Stunted growth

Causes leaves to

become irregular,

distorted and

cupped


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Magnesium (Mg) As a component

of chlorophyll

Activates many

plant enzymes in

carbohydrate

metabolism

Yellowing of

leaves, sometimes

with red spots on

leaf surfaces

Sulphur (S) As a component

of certain amino

acids and certain

coenzymes

involved in

respiration

Initial yellowing of

young leaves

spreading to

whole plant


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Boron (B) Helps in translocation

of sugars, calcium

uptake and

germination of pollen

grains

Involved in

carbohydrate

metabolism and

needed for cell division Acts as a cofactor in

chlorophyll synthesis

Leaves become thick,

curled and brittle

Death of terminal buds

Abnormal growth

Molybdenum (Mo) Involved in nitrogen

fixation during protein

synthesis

Pale green leaves

Chlorosis between

veins of mature leaves

Reduces crop yield


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Zinc (Zn) As a cofactor in

carbohydrate

metabolism Needed for the

synthesis of auxin

Formation of leaves

Stunted growth

Leaves with irregular

areas of chlorosis

Reduced leaf size

Manganese (Mn) Activates the

enzymes involved in

photosynthesis,

respiration and

nitrogen

metabolism

Pale green leaves

with a network of

green veins

Grey spots appear

between veins


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Copper (Cu) As component of

enzymes

Involved in

photosynthesis, as wellas carbohydrate and

nitrogen metabolism

Needed for flower

formation and

reproductive growth

Required for lignin

synthesis which is

needed for cell wall

strength and

prevention of wilting

Stunted growth

Yellowing of leaves

Brown spots appear in

terminal leaves Wilting and eventual

death of tips of young

shoots

Iron (Fe) As a cofactor in the

synthesis of

chlorophyll

Required for the

growing parts of

plants

Stunted growth

Chlorosis in

between veins of

young leaves


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the importance of macronutrients and micronutrients in plants

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