micro nutrition an important tool for increasing crop yield particularly area were it is more deficient such as alkali soils and some acidic soil ( eg Mo, B )...

1. “MICRONUTRIENTS – IMPORTANCE IN
CROP NUTRITION"
UTTAM KUMAR
Master of Science in Agriculture
(Soil Science and Agricultural Chemistry)
28 SEP. 2015

2. Micronutrients- An introduction
The world ‘micronutrients’ represents some essential
nutrients that are required very small quantities for the
growth of plants and micro-organisms.
There are 17 essential elements for plant growth, out of these
elements 8 elements are considered as micronutrients. They
are – iron (Fe), manganese(Mn), copper(Cu), zinc(Zn),
boron(B) molybdenum(Mo), nickel(Ni) and chlorine(Cl).
Out of these micronutrients iron (Fe), manganese(Mn),
copper(Cu), zinc(Zn), behave like cations, and boron(B)
molybdenum(Mo), and chlorine(Cl) behave like as anion.

3.  So that the chemistry of micro- nutrients cations are
different from micro- nutrients anions.
 Among these 8 micro- nutrients, the content of iron (Fe) in
soil as well as in plants is the highest and sometimes higher
than even P and S content.
 Micronutrients are also called trace elements, oligo
elements or spurn elements.

4. Major sources of micro-nutrients
S.no. Micro- nutrients Minerals
1.
Fe
Hor nblende, Hametite, Goethite, Pyrite, Magnetite,
Olivine.
2.
Mn
Pyrolusite, Maganite, Rhodonite.
3.
Cu
Chalcopyrite, Covelite, Cuprite, Malachite.
4.
zn
Sphalarite, Smithsonite,
5.
B
Tourmaline, Colemanite, Borex,Kernite.
6.
Cl
Apatite, Murate of potash, Sodium chloride.
7
Mo
Molybdenite, Wulfenite, Ferrimolybdenite.
8. Ni Serpentine, Olivine

5. Form of micro-nutrients absorbed by plants
S.No. Micro-nutrients Ionic forms
1. Fe Fe2+, Fe3+
2. Mn Mn2+, Mn4+
3. Cu Cu2+
4. Zn Zn2+
5. B H2BO3
-
, HBO3
2-
, BO3
3-
, B4O7
2-
6. Cl Cl-
7 Mo MoO4
2-
8. Ni Ni2+

6. Micro-nutrients Essentiality Discoverer
S.No. Micro-nutrients Discoverer
1. Fe Griss – 1843
2. Mn McHargue -- 1922
3. Cu A.L.Sommer and C.P. Lipman -- 1931
4. Zn A.L.Sommer and C.P. Lipman -- 1926
5. B Warington – 1923
6. Cl T.C. Broyer --1954
7.
Mo Arnon and Stout – 1939
8. Ni Brown, Welch, and cary -- 1987

7. Micro –nutrients amount In soil
Micro –nutrients Rang Average
Fe 0.5 – 50% 3 – 4%
Mn 20 – 3,000 ppm 600 ppm
Cu 2 – 100 ppm 9 ppm
Zn 10 – 300 ppm 50 ppm
B 2 – 200 ppm 50 ppm
Cl 1-100ppm 50ppm
Mo 0.2 – 5.0 ppm 1.2 ppm
Ni 2 – 750 ppm 50 ppm

8. Micro –nutrients amount In plants
Micro –nutrients Amount In Plants(ppm)
Fe 100
Mn 50
Cu 6
Zn 20
B 20
Cl 100
Mo 0.1
Ni 2

9. iron – major function
Important constituent of two group of protien-
1.Heme- protein 2. Fe-S protein
Iron is involved in the production of chlorophyll.
Oxygen carrier.
Nucleic acid metabolism.
Chlorophyll synthesis.
Protein synthesis.
Act as catalyst in N2 Reeducates.
Structural component of phorphyrin molecules.
Required for nitrogen fixation.

10. iron – deficiency symptoms
 younger leaves exhibit interveinal chlorosis. Without
dead spot this is the only symptom - Iron
 Plant having ≤ 50 ppm (30ppm) Fe, than Fe deficiency
will occur.
 Whole plants turning – necrotic.
 Due to deficiency of Fe-
1. White eye in paddy
2. yellow blotch in citrus.
3.green rating in potato.

11. Fe- deficiency in Maize

12. Soybean

13. manganese – major function
 Manganese is necessary in photosynthesis, nitrogen
metabolism and to form other compounds required for plant
metabolism.
 Important constituent of Suproxide – dimutase (Mn-SOD).
 It take part in electron transport in photosysytem -2.
Mn act as enzyme activation, and this enzyme produce amino
acid.
Deficiency symptoms:-
 In addition to interveinal chlorosis on young leaves, grey or tan
necrotic spots develop in chlorotic areas.
 Plant containing less than 25 ppm Mn then deficiency symptoms
will occur.

14. Common micro deficiency for soybean and small grains
Susceptible soils:
High pH (alkaline) soils (>6.8)
High organic matter soils (>6%)
Due to Mn deficiency :-
1.gray spack in Oat
2.pahala blight in sugercane.
3.marshy spot in pea.
4.spekeld yellow in beetrot

15. Grey Speck in Oat

16. Soybean- compelete intervinal chlorosis.

17. copper – major function
 Copper is necessary for carbohydrate and nitrogen metabolism.
 Eletron carrier in oxidation –reduction reaction.
 Utilization of iron in chlorophyll synthesis.
 Enhance the fertility of mala flower.
 Enhance disease resistance in plants
Deficiency symptoms:-
While younger leaves have interveinal chlorosis, the tips and lobes
of leaves remain green followed by veinal chlorosis and rapid,
extensive necrosis of leaf blade
Due to Deficiency of copper-
1.Dai back in citrus.
2.Reclamation of rice

19. zinc– major function
 Zinc is an essential component of three enzymes-
1. carbonic anhydrase.
2.Alcoholic dehydrogenase.
3.Suproxide dismutase. for energy production, protein synthesis,
and growth regulation.
 Important in the synthesis of IAA.
 Essential for water uptake.
 Play important role in stablization of protein.
 Deficiency symptoms:-
 Plant containing less than 15 ppm Zn than deficiency symptoms will
occur.
 Intervinal chlorosis first appear in younger leaves.
 Reduse the size of the leaves- little leaf.
 Mainly occur in calcareous soils.

20.  Due to Zn deficiency fallowing deficiency symptoms
will occur.
 1. khaira disease in rice.
 2. white bud in maize.
 3. little leaf in cotton , chilli, brinjal. Citrus mango. Etc.
 4.bronzing in Guava.

22. Tomato

23. Boron– major function
 A primary function of boron is related to cell wall formation.
 Important for pollination and pollen germination.
 Help in k translocation as well as stomatal opening.
 Calcium metabolism.
 Act as regulator of k/Ca ratio.
 Essential for translocation of sugar.
Deficiency symptoms:-
 Terminal buds die giving rise to a witch's broom.
 Young leaves become very thick and leathery and chlorotic.
 Rust-coloured cracks and corking occur on young stems,
petioles and flower stalks.
 Young leaves crinkled.

24.  Common deficiency for alfalfa and other forages
 Susceptible soils: Sands and low OM soils, Dry soils.
 Due to B deficiency fallowing deficiency symptoms will
occur.
1. Brown or black heart in beet rot
2. Hallow stem in cauliflower.
3. Browning or heart rot in sugarcane.
4. Internal cork in apple.
5. Necrosis in Aonla
6. Top sickness in tobacco.

25. Rice

26. Rape

27. Molybdenum-major function
 Mo is important constituent of nitrogenase enzyme , which
help in N2 fixation in legumes crops.
 Mo is essential component of NO3
- reductase enzymes.
this enzyme concerted in chloroplast which catalzes the
conversion of NO3
- to NO2
-
 protein synthesis and sulfur metabolism are also affected by
molybdenum.
 Molybdenum has a significant effect on pollen formation.
 Also reported to have an essential role in iron absorption and
translocation in plants.

28. Mo - Deficiency symptoms
 The deficiency symptoms of Mo is first appear In Older
leaves , interveinal chlorosis with some dead spots.
 Due to Mo deficiency fallowing deficiency symptoms
will occur.
1. whip tail in cauliflower.
2. yellow spot in citrus.
3. scald in beans.

30. Chlorine - Functions
 Essential for stomatal opening.
 Cl is related to electrical charge balance in physiological
functions in plants.
 It indirectly affects plant growth by stomatal regulation of
water loss.
 Deficiency symptoms
 highly branched root systems are the main chloride-
deficiency symptoms, which are found mainly in cereal
crops.
 chloride deficiencies have been reported on sandy
soils,humid region with high rainfall area.
 willting and twisting in wheat due to Cl deficiency.