Plant Nutrient Functions, Deficiency and Toxicity Symptoms – AgriBooks

Plant Nutrient Functions, Deficiency and Toxicity Symptoms

The element is involved directly in the nutrition of the plant quite apart from its possible effects in correcting some unfavourable microbiological or chemical condition of the soil or other culture medium.

Essential plant nutrients: A total of only 17 elements are essential for the growth and full development of higher green plants according to the criteria laid down by Arnon and Stout (1939). This theory was revised by Arnon in 1953. These criteria are:-

  1. A deficiency of the given element makes it impossible for the plant to complete its life cycle.
  2. The deficiency is specific for the given element and not replaceable by another element.
  3. The element is a constituent of an essential metabolite or it is required for the action of an enzyme system.
  • According to Arnon only 16 elements are essential for the growth but Ni is also included in essential elements in 2010.

Plant Nutrient their functions, deficiency symptoms and toxicity symptoms

Plant Nutrient





- N is biologically combined with C, H, O, and S to create amino acids, which are the building blocks of proteins. Amino acids are used in forming proto-plasm, the site for cell division and thus for plant growth and development.

- Since all plant enzymes are made of proteins, N is needed for all of the enzymatic reactions in a plant.

- N is a major part of the chlorophyll molecule and is therefore necessary for photosynthesis.

- N helps in vegetative growth.

- Grain is soft by N.

- N is a necessary component of several vitamins.

- N improves the quality and quantity of dry matter in leafy vegetables and protein in grain crops.

- N create softness in leafy vegetables.

- N is component of Chlorophyll

Pale green to light yellow colour (“V” shape chlorosis) appearing first on older leaves, usually starting at the tips.

N deficiency causes early maturity in some crops, which results in a significant reduction in yield and quality.

‘V’ shaped chlorosis on older leaves or yellowing at tip.

•           Plant remain Dwarf.

Vigorous vegetative growth coupled with dark green colour.

The vegetative growth is prolonged and crop maturity is somewhat delayed.

Crop logging.

Decrease storage life of fruit and Vegetables.

Decrease tuberization in potato.

Decrease of sugar content in sugarcane.

Decrease TSS content in fruits


Important for plant development including:

development of a healthy root system

normal seed development

uniform crop maturation

photosynthesis, respiration, cell division, and other processes

Essential component of Adenosine Triphosphate (ATP), which is directly responsible for energy transfer reactions in the plant. It act as “Energy Currency”.

Essential component of DNA and RNA, and phospholipids, which play critical roles in cell membranes.

It increases root nodules in pulses crops.

•           It is also known as “Key of Life”

Under severe deficiency, purpling of old leaves and stems may appear.

Lack of P can cause delayed maturity and poor seed and fruit development.

•           Bronzing appearance on older leaves and later develops red purple colour.

The excess of phosphorus appears mainly in the form of micronutrient deficiency mostly for iron, zinc and manganese.

It is an interesting fact that excess phosphorus, however, may also cause typical calcium deficiency symptoms.


Responsible for:

regulation of water usage in plants

disease resistance

stem strength

Involved in:


drought tolerance

improved winter-hardiness

protein synthesis

Linked to improve-ment of overall crop quality, including handling and storage quality.

It controls closing and opening of stomata so known as “Traffic police of plant” .

•           It increases vigorous-ness of seed.

Commonly causes scorching or firing along leaf margins in old leaf.

•           Deficiencies most common on acid sandy soils and soils that have received large applications of Ca and/or Mg.

As a result of excess potassium, plants show the typical symptoms of magnesium and possibly calcium deficiency due to a cation imbalance in the plant.


Ca has a major role in the formation of the cell wall membrane and its plasticity, affecting normal cell division by maintaining cell integrity and membrane permeability.

It acts as a detoxifying agent by neutralizing organic acids in plants.

Ca is essential for seed production in peanuts.

Structural component of chromosome.

Important for groundnut, tobacco and potato.

Tip hooking is common problem.

Most often occurs on very acid soils where Ca levels are low.

•           Other deficiency effects such as high acidity usually limit growth before Ca deficiency is apparent.

Excessive calcium content will produce magnesium or potassium deficiency in plants, although this depends on the concentration of these elements.



Primary component of chlorophyll and is therefore actively involved in photosynthesis.

Structural component of ribosomes, which are required for protein synthesis.

• Involved in phosphate metabolism, respiration, and the activation of several enzyme systems.

•           Interveinal chlorosis (pucker chlorosis) in old leaf. Particularly found in cruciferae, solanaceae and rosacea plants.

Magnesium toxicity are rare and not generally exhibited visibly.


Required for the synthesis of the sulfur-containing amino acids cystine, cysteine, and methionine, which are essential for protein formation.

Involved with:

Development of enzymes and vitamins (Vit-B).

Promotion of nodulation for N fixation by legumes

Seed production chlorophyll formation

Formation of several organic compounds that give characteristic odors to cruciferae, and alliaceae family.

•           It is increase oil content in oil seed crops.

Chlorosis of the new leaves.

•           Symptoms resemble those of N deficiency; can lead to incorrect diagnosis.


Essential for:

germination of pollen grains and growth of pollen tubes

seed and cell wall formation

development and growth of new cells in meristematic tissue

Forms sugar/borate complexes associated with the translocation of sugars, starches, N, and P.

Important in protein synthesis.

Increase tobacco yield 15-30%.

Control cell membrane permeability.

May occur on very acid, sandy-textured soils or alkaline soils.

Decrease internode length.

Top sickness. 


Cu is part of the chloroplast protein plastocyanin, which forms part of the electron transport chain.

Cu may have a role in the synthesis and/or stability of chlorophyll and other plant pigments.

It synthesizes carotene.

Increase Fe absorption.

Reduced leaf size.


Serves as a catalyst in chlorophyll synthesis.

Involved in many oxidation-reduction reactions during respiration and photosynthesis.

•           Fe is carrier of oxygen.

White chlorosis that progresses over the entire new leaf.

With severe deficiencies, leaves turn entirely white.



Serves as a catalyst in chlorophyll synthesis along with iron.

Activates several important metabolic reactions (enzymes).

• Plays a direct role in photosynthesis.

Interveinal chlorosis in new leaf.

•           Occurs most often on high organic matter soils and soils with neutral to alkaline pH with low native Mn content.


Aids in the synthesis of plant growth compounds and enzyme systems.

Tryptophan synthesis.

• Necessary for the production of chlorophyll, carbohydrates, and growth hormones.

Shortened internodes between new leaves.

Occurs most often on alkaline (high pH) soils or soils with high available P levels.

In Indian soil mostly found Zn deficiency about 47-48%


Required for the synthesis and activity of nitrate reductase; the enzyme system that reduces NO3- to NH4+ in the plant.

Essential in the process of symbiotic N fixation by Rhizobia bacteria in legume root nodules.

Increase radish and carrot sweetness.

Interveinal chlorosis.


•           Occurs principally on very acid soils, since Mo becomes less available with low pH.


Involved in:

energy reactions in the plant

breakdown of water

regulation of stomata guard cells

maintenance of turgor and rate of water loss

plant response to moisture stress and resistance to some diseases

Activates several enzyme systems.

• Serves as a counter ion in the transport of several cations in the plant.

Chlorosis in upper leaves.

Overall wilting of the plants.

•           Deficiencies may occur in well drained soils under high rainfall conditions.

Burning of leaf tip or margins.  Bronzing, yellowing and leaf splitting.  Reduced leaf size and lower growth rate.


Essential in the process of symbiotic N fixation by Rhizobia bacteria in legume root nodules.

•  Has not been proven to be essential for the growth of all higher plants.

Causes N deficiency: chlorotic leaves and stunted plants.

Occurs in areas with soils

deficient in native Co.


Component of the urease enzyme.

• Essential for plants supplied with urea and for those in which ureides are important in N metabolism.

•           Symptoms and occurrence are not well documented but may include chlorosis and necrosis in young leaves and failure to produce viable seeds.


Beneficial for paddy.


Sodium is involved in osmotic (water movement) and ionic balance in plants.

         It is helpful in tuberization of potato.


Direct stimulation of plant growth and yield through more upright growth and plant rigidity.

Suppression of plant diseases caused by bacteria and fungi (such as powdery mildew on cucumber, pumpkin, wheat, barley; grey leaf spot on perennial rye grass; leaf spot on Bermuda grass; rice blast) 

Improved insect resistance (such as suppression of stem borers, leaf spider mites, and various hoppers)

Alleviating various environmental stresses (including lodging, drought, temperature extremes, freezing, UV irradiation) and chemical stresses (including salt, heavy metals, and nutrient imbalances)

         Silicon is an important element for animals where it strengthens bones and connective tissue


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