This document discusses several micronutrients that are essential for plant growth including iron, manganese, zinc, copper, boron, molybdenum, chlorine, and nickel. Micronutrients are required by plants in small quantities and include trace elements, minor elements, and oligo elements. Chelates are organic compounds that bond with micronutrients like iron, zinc, copper, and manganese, increasing their solubility and availability to plant roots. The document discusses sources of each micronutrient in soil, factors affecting their availability, functions in plants, and deficiency symptoms.

2. MICRONUTRIENT
• also called as trace elements , minor
elements, oligo elements or spurn elements.
• It is a mineral element that are required very
small quantities for the growth of plants.

3. MICRONUTRIENT

5. CHELATES
• Greek word - Claw
• they are soluble organic compounds that
bonds with metals such as Fe, Zn, Cu& Mn
increasing their solubility and their supply to
plant roots.
NATURAL ORGANIC CHELATES :
Root exudates ,product of microbial activity,
degradation of organic matter, citric acid ,oxalic
acid.

6. … cont..,
SYNTHETIC CHELATES:
• Chelate at ≤ 7 pH
DTPA[ Diethylene triamine penta acetic acid]
EDTA[ Ethylene diamine tetra acetic acid ]
• stable at entire pH
EDDHA[ Ethylene Diamine Dihydroxy Phenyl
acetic acid ]

8. IRON
• Discovered by Griss [1843].
• ranges 0.5-50 % [of avg 3-4%] in soil ,& 50-
250ppm [100ppm] in plants.
• SOURCES:
• Earth crust contains about 5%
• 10 & 20 minerals such as
Olivene
Pyrite
Hematite
Goethite
Magrulite
Limestone

9. IRON
• FORMS: [CATIONIC]
• Fe is absorbed by plants as Fe 2+ , Fe 3+ and
chelated irons
• IN SOIL:
Primary & secondary minerals Fe
Absorbed Fe
Organic Fe
Solution Fe
Fe2+

10. IRON
• MOBILITY: Immobile in soil.
• TRANSFORMATION:
Soil
solution
c
Nutrient uptake
by plants
Exchange and
surface
adsorption
Soild phase
minerals and
precipitates
Organic matter
&microorganism

11. FACTORS AFFECTING Fe AVAILABILITY:
• Soil pH [High] , bicarbonates and carbonates.
• excessive H2o and poor aeration.
• Organic matter.
• Interaction with other nutrients:
 deficiency can occur due to the accumulation
of Cu, Mn,Zn,Mo and P..
 Fe availability decreases when the soils are
having more NO3
- than NH4
+.
 Deficiency of K or Zn can reduce Fe
translocation with in plants.

12. FUNCTIONS OF IRON :
• Synthesis of chlorophyll.
• Oxygen carrier.
• Structural component of phorphyrin molecules
like cytochrome , heme group , non heme group
like ferredoxins.
• Component of flavoprotein like
 FMN= Flavin Mono nucleotides
 FAD= Flavin Adinosine Dinucleotide.
• act as catalyst in N2 reductase
• Required for nitrogen fixation.

13. DEFICIENCY SYMPTOMS:
 It occurs in younger leaves since fe is
immobile element within plant .
 It occurs in soils of calcareous or
alkaline soils and poorly drained H2O
logged soils.
 Younger leaves develop interveinal
chlorosis with progresses rapidly over
the severe cases entire leaf turns
yellow colour.
 White eye in paddy
 Yellow blotch in citrus
 Greening in potato

14. MANGANESE- McHargue
SOURCES:
• Ranges 20- 3000ppm [avg 600ppm].
• In the form of oxides and hydroxides.
o Manganite MnO [OH]
o Braunite Mn2O2
FORMS: [ Mn 2+, Mn4+]
 Mn Mineral
 exchange Mn 2+
 Organic bound Mn
 Solution Mn 2+

15. FACTORS AFFECTING Mn AVAILABILITY:
1.SOIL pH AND CARBONATES:
Liming to acid soils decreases solution and
exchange Mn 2+ due to precipitation Mn 2+ as
MnO2.
2.EXCESSIVE H2O AND POOR AERATION:
H2O logging will reduce O2 and lower redox
potentialwill increases soluble Mn 2+.
poor aeration increases Mn availability..
3. ORGANIC MATTER:
Increases solution and exchangeable Mn.

16. 4. CLIMATIC FACTOR :
Increase in soil temp during the cropping season
improves Mn uptake ,because of greater plant
growth and root activity
5. SOIL MICRO ORGANISM:
oxidize Mn 2+ to Mn 4+.
FUNCTIONS OF Mn:
Helps in chlorophyll formation.
Involves in photosynthesis ,particuraly in O2
evolution
Involves in oxidation reduction process in
decarboxylation and hydrolysis reaction.

17. Involves in enzyme systems and various
enzyme reactions in the citric acid cycle.
It is a substitute for Mg 2+ in many of the
phosphorylating and group transfer reactions.
DEFICIENCY OF Mn:
immobile in plant and def. starts in the
younger leaves.
Interveinal chlorosis occur
Oats - Grey specks/ streaks
Peas – Marsh spot
Sugarbeet - speckled yellow
Sugar cane – Pahala blight [midrib pale green and
white]

18. ZINC – A.L.Sommer and C.P.Lipman
SOURCES:
• Sphalarite
• Smithsonite
FORMS:[ Zn 2+]
 solution Zn 2+
 Absorbed Zn 2+

19. FACTORS AFFECTING Zn AVAILABILITY:
• Higher the soil pH
• poor aeration
• SO 4 & N can increase the Zn uptake in plants.
FUNCTIONS :
Helps in reproduction of certain plants
Influence the activity of dehydrogenase enzymes
Involves in auxin metabolism like tryptophan
synthetase
Essential for water uptake

20. DEFICIENCY OF Zn:
Interveinal chlorosis first appear in younger
leaves
Reduce the size of the leaves – Little leaf
Rice - Khaira disease
Maize – White bud
Guava – bronzing
Litle leaf – Cotton,Chilli,Citrus,Mango

21. COPPER –A.L.Sommer &C.P. Lipman
• Ranges 2- 100 ppm .
SOURCE:
Chalcopyrite
Covelite
Cuprite
Malachite.
FORMS:[Cu 2+]
soil solution
Specific adsorpton sites
Inorganic matter and living organisms

22. FACTORS AFFECTING Cu AVAILABILITY:
1. SOIL TEXTURE:
sandy soils contain lower amounts of cu than slit
and clay soils.
2. pH:
the concentration of Cu in soil solution decreases
with increase in pH.
3. INTERACTION WITH OTHER NUTRIENTS:
 Increase N supply to crops reduce mobility of Cu in
plants.
 High concentration of Zn,Fe and P in soil solution also
depress Cu absorption by plant roots

24. BORON –Warington
• Ranges 2-200 ppm [50 ppm]
SOURCES:
 Tourmaline
 Colemanite
 Borex
 Kernite.
FORMS:
 H2BO3
–
 HBO3
2-
 BO3
3-
 B4O7
2-

25. FACTORS AFFECTING B AVAILABILITY :
1. SOIL TEXTURE :
plants take up larger quantity of B from sandy
soils than fine texture soil at equal concentration of
water soluble B.
2. SOIL pH:
less availability of B with increase in pH
3. SOIL MOISTURE:
restricted moist supply reduce the B avail.. In the
root zone.

26. FUNCTIONS:
• New cell development in meristematic tissue
• Pollination, fruit /seed set.
• Translocation of sugars ,starches,N and P.
• synthesis of amino acids and proteins.
• nodule formation in legumes
DEFICIENCIES:
 flowering and fruit development are
restricted.
 sterility and malformation of reproductive
organs

27. • Thickened and curled leaves
• Discolouration ,cracking or rotting of fruit
,tubers or roots
Apple – Internal cracking
Cotton - Brown /Black heart [weeping disease]

28. MOLYBDENUM- Arnon & stout
• ranges 0.2- 5.0 ppm
SOURCES:
Molybdenite
Wulfenite
Ferrimolybdenite
FORMS:[MoO4
2-]
primary and secondary minerals
Exchangeable Mo held by Fe and Al oxides
Mo in soil solution
Organically bound Mo

29. FACTORS AFFECTING Mo AVAILABILITY:
1. SOIL pH AND LIMING:
 Mo availability increases with increasing p H.
 liming to correct acidity will increase Mo avail..
 Mo avail.. Decreases with app of acid forming
fertilizer[NH4 ] 2 SO 4.
2. REACTION WITH Al AND Fe
3. INTERACTION WITH OTHER NUTRIENTS
ENHANCES Mo absorption
Mg and P
NO3
-
DECRESES Mo ABSORPTION
High level SO4
Cu AND Mn
NH4

30. FUNCTION:
essential component of NO3
- reductase enzymes .
Important constituent of nitrogenase
enzyme,which help in N2 fixation in legume crops.
Essential role in iron absorption and
translocation in plants.
DEFICIENCY:
cauliflower – whip tail
Citrus- yellow spot
Beans- scald

31. CHLORINE-T.C.Broyer
SOURCES:
Apatite
Murate of potash
Nacl
FORMS:[Cl- ]
FUNCTIONS:
Essential for stomatal opening
It is related to electrical charge balance in
physiological functions in plants.

32. DEFICIENCY:
• Highly branched root system
• Wilting and twisting in wheat due to Cl
deficiency

33. B,Mo CYCLE IN SOIL
SOLUTION
B [H3 BO3]
Plant
Uptake
Fertilizer
Primary and
secondary B
minerals
Absorbed
B
Organic
B
Residue

34. NICKEL- Brown,Welch&Cary
• Taken by plant as Ni 2+ .
• High levels of Ni may induce Zn or Fe
deficiency.
• Essential for N metabolism.