This document discusses essential plant nutrients, their functions, and deficiency symptoms. It outlines 17 essential elements and classifies them based on amount required and role in plants. Major nutrients like nitrogen, phosphorus, and potassium are required in large quantities, while micronutrients like iron, manganese, and zinc are needed in trace amounts. Each nutrient serves important functions, such as carbon and oxygen composing organic compounds, and nitrogen forming proteins. Deficiency symptoms for each nutrient are also described, such as pale leaves for nitrogen deficiency and interveinal chlorosis for magnesium. The document provides an in-depth overview of essential nutrient needs for plant growth.

1. ESSENTIAL ELEMENTS/NUTRIENTS: FUNCTIONS AND DEFICIENCIES
Dr. K. Vanangamudi
Formerly Dean (Agriculture),
Dean Adhiparasakthi Agricultural College,
Professor & Head,
Seed Science & Technology, TNAU, Coimbatore.
1. Classification of essential nutrients
1.1. Based on the amount required by the plant
 Major nutrients – required in large quantities eg. N, P, K.
 Secondary nutrients – required in lesser quantities compared to major nutrients eg. Ca,
Mg, S.
 Micronutrients – required in trace quantities eg. Fe, Mn, Zn, Cu, B, Mo.
1.2. Classification based on the role of element in plant system (according to TRUOc,
1954)
 Accessor structural elements: N, P, S
 Regulator and carriers: K, Ca, Mg
 Catalyst and activators: Fe, Mn, Zn, Cu, Mo, Cl, B.
 Seventeen elements are considered essential to plant growth.
 Carbon (C), hydrogen (H) and oxygen (O) are the most abundant elements in plants.
 Carbon, H and O are not considered as mineral nutrients.
2. Essential nutrients and their principal forms for uptake
Nutrient Chemical symbol Principal forms for uptake
Carbon C CO2
Hydrogen H H2O
Oxygen O H2O.O2
Nitrogen N NH+4
.NO-3
Phosphorus P H2PO-4
, HPO2
-4
Potassium K K+
Calcium Ca Ca2+
Magnesium Mg Mg2+
Sulphur S SO2
-4
, SO2
Iron Fe Fe2+,
Fe3+
Manganese Mn Mn2+
Boron B H3BO3
Zinc Zn Zn2+
Copper Cu Cu2+
Molybdenum Mo MoO2
-4
Chlorine Cl Cl-

2. Nickel
3. Functions of essential nutrients in plants
Nutrient Function
Carbon (C)  Basic molecular component of carbohydrates, proteins, lipids
and nucleic acids
Oxygen (O)  Occurs in all organic compounds of living organisms
Hydrogen (H)  Hydrogen plays a central role in plant metabolism.
 Important in ionic balance and as main reducing agent.
 Plays a key role in energy relations of cells.
Nitrogen (N)  Component of proteins to nucleic acids and chlorophyll.
 Essential role in plant growth.
 Also foods in soils.
Phosphorus (P)  Central role in plants is in energy transfer during respiration
ADP + Pi → ATP and protein metabolism.
 Root growth and photosynthesis.
Potassium (K)  Helps in osmotic and ionic regulation.
 Cofactor or activator for many enzymes of carbohydrate and
protein metabolism.
 Resistance to cold, disease and insects.
Calcium (Ca)  Involved in cell division and maintenance of membrane
integrity.
 Signal transduction pathway.
Magnesium (Mg)  Component of chlorophyll.
 Cofactor for many enzymatic reactions.
Sulphur (S)  Involved in plant cell energy.
Iron (Fe)  Essential component of many heme and nonheme Fe enzymes.
 Involved in key metabolic function such as N fixation,
photosynthesis and electron transfer.
 Chlorophyll production.
Zinc (Zn)  Essential component of several dehydrogenases and peptidases,
including carbonic anhydrase, alcohol dehydrogenase, glutamic
dehydrogenase and malic dehydrogenase.
 Synthesis of protein, hormones, enzymes.
Manganese (Mn)  Involved in the O2 – evolving system of photosynthesis.
 Component of the enzymes arginase and phosphortransferases.
 Chlorophyll production.
Copper (Cu)  Constituent of enzymes like cytochrome oxidase, ascorbic acid
oxidase and laccase.
Boron (B)  Involved in carbohydrate metabolism and synthesis of cell wall
components.
 Pollen production, fertility and fruit formation.
Molybdenum (Mo)  Required for the normal assimilation of N in plants.
 Essential component of nitrate reductase as well as nitrogenase
(N2 fixation enzymes).
Chlorine (Cl)  Essential for photosynthesis and as an activator of enzymes
involved in splitting water.
 Involved osmoregulation of plants growing on saline soils.

3. Nickel (Ni) Involves in N metabolism and nitrogen fixation
4. Deficiency symptoms of nutrients
4.1. Nitrogen (N)
 Promotes rapid vegetative growth
 Gives plants healthy green colour
 Deficiency:
 Stimulated growth, pale yellowish colour.
 Burning tips and margins of leaves starting at the bottom of the plant.
4.2. Phosphorus (P)
 Stimulates early growth and root formation.
 Hastens maturity.
 Promotes seed production.
 Makes plants hardy.
 Deficiency:
 Small root growth, spindly stalk, delayed maturity.
 Purplish discoloration of leaves.
 Dying of tips of older leaves, poor fruit and seed development.
4.3. Potassium (K)
 Improves plant ability to resist disease and cold.
 Aids in the production of carbohydrates.
 Deficiency:
 Slow growth.
 Margin on leaves develop a scorched effect on the older leaves.
 Weak stalk, shriveled seed and fruits.
4.4. Calcium
 Absorbed by plants as Ca2+
and concentration in plant ranges from 0.2 to 1.0%.
 Deficiency:
 Young leaves of terminal buds dieback at the tip and margins.
 Root may become short, stubby and brown.
 Causes acidity of soil.
 Cell may become rigid and brittle.
 Young leaves of cereals remain folded

4. 4.5. Magnesium
 Absorbed as Mg2+
and concentration in plant varies between 0.1 and 0.6%.
 Deficiency:
 Interveinal chlorosis.
 Stiff brittle, twisted, wrinkled and distortion of leaves.
 Cotton – lower leaves develop a reddish purple finally nicrotic (Redding of
leaves).
 In brassica, chlorosis with interveinal mottling uniformly distributed in older
leaves and other vascular tissues remain green called Puckering.
4.6. Sulphur
 Absorbed by plant roots as SO4
2-
ions.
 Concentration in plants ranges between 0.1 and 0.4%.
 Deficiency:
 Stunted growth, pale green to yellow colour.
 Immobile in plants and plants symptoms start first at younger leaves.
 Poor seed set in rapeseed.
 Tea –tea yellows.
4.7. Iron
 Absorbed by plants roots as Fe2+
, Fe3+
.
 Concentration in plant tissue is 50-250 ppm.
 Deficiency:
 Occurs in younger leaves since Fe is immobile element.
 Occurs in calcareous or alkaline soils and poorly drained water logged soils.
 Younger leaves develop interveinal chlorosis.
 Entire leaf turns yellow colour.
4.8. Manganese
 Mn concentration in plant ranges from 20 to 500 ppm.
 Deficiency:
 Immobile in plant and deficiency starts in the younger leaves.
 Interveinal chlorosis occurs.
 Oats - gray specks / streaks
 Peas - marsh spot
 Sugarbeet - speckled yellow

5.  Sugarcane - pahala blight
4.9. Zinc
 Normal concentration in plant is 25 to 150 ppm.
 Deficiency:
 Light yellow or white areas between the veins of older leaves.
 Death of tissue, discoloured.
 Malformation of fruits.
 Cotton : White bud (or) little leaf
 Citrus : Mottle leaf
 Potato : Fern leaf
 Fruit trees : Rosette (Upnormal growth)
 Paddy : Khaira
4.10. Copper
 Absorbed Cu2+
.
 Normal concentration in plants is 5-20 ppm.
 Deficiency:
 Chlorosis, withering and distortion of terminal buds.
 Guava - cracking of fruits and terminal bud dieback.
4.11. Boron
 Since it is immobile, deficiency occurs in terminal bud growth.
 Poor pollen production and fertility.
 Restricted flowering, fruit development and fruit set.
 Sterility and mal formation of reproductive organs.
 Discolouration, cracking or rotting of fruit, tubers or roots.
 In apple, Internal cracking.
 Break down of internal tissue in root crops gives rise to darkened areas - brown heart /
black heart.
 Cotton - weeping disease.
4.12. Molybdenum
 Absorbed as molybdate (MoO4).
 Plant contains <1 ppm Mo.
 Deficiency:

6.  Inhibits flower formation.
 Whiptail in cauliflower.
4.13. Chlorine
 Absorbed by plants as Cl-
through roots and aerial parts.
 Normal concentration in plant is 0.2-2.0%.
 Deficiency:
 Partial wilting and loss of turgidity.
 Necrosis, leaf bronzing and reduction in growth.
4.14. Nickel
 Content in plant is 0.1 - 1.0 ppm.
 Legumes: whole leaf chlorosis along with necrotic leaf tips in cowpea.