It is an overview of role of zinc in crop production, how it respond upon fertilization

1. Speaker: Dibakar Roy
M.Sc. (Ag.), 4th Semester
Chairman: Professor Biswapati Mandal
DEPARTMENTOFAGRICULTURALCHEMISTRYANDSOILSCIENCE
FACULTYOFAGRICULTURE
BIDHANCHANDRAKRISHI VISWAVIDYALAYA
Course No. ACSS-592 Date: 11.05.2016SEMINAR-II
1
Role of Zinc in Crop Production

2. Introduction
 Zn is an important micronutrient for plant growth.
 Essentiality of Zn was discovered by- A.L. Sommer and C.P. Lipman
 In plant Zn content varies from- 27 ppm to 100 ppm
 In Soil Zn content in indian soils varies from-
 Arid/semi-arid climate - 20-89 mg/kg
 Humid/sub-humid tropics – 22-74 mg/kg
 Vertisols - 69-76 mg/kg
 Oxisols (coarse textured)- 24-30 mg/kg
Essential Nutrients
Macro Nutrients
Micro Nutrients
Katyal and Vlek, 1985

3. Role of Zinc in Plant system
Low Molecular weight complexes of Zinc- In plant leaves soluble Zinc occurs mainly as
anionic compound possibly associated with amino acid.
Carbohydrate metabolism-
 Photosynthesis- Zinc is a constituent of Carbonic anhydrase enzyme, which have
role in co2 fixation.
Protein metabolism- Zinc is necessary for the activity of RNA polymerase enzyme and it
protects ribosomal RNA from attack by the enzyme ribonuclease.
Membrane integrity- The role of Zinc in maintaining the integrity of cellular membranes
involving structural orientation of macromolecules and maintenance of ion transport
systems.
Auxin metabolism- Zinc is required for synthesis of Auxin, zinc is required for synthesis of
tryptophan which is precursor of Auxin.

4. Forms of Zinc in Soil
Mineral form- Zinc exist as Zinc sulphides, Zinc carbonates, and Zinc
silicates.
On weathring Zn ion released.
Sphalarite- ZnS
Smithsonite- ZnCO3
Willemite- ZnSiO4
Franklinite- ZnFe2O4
Adorbed form- Zn is adsorbed on the surface of clays, oxide minerals,
carbonates and organic matters.
Solution form- In soil solution Zn exists as Zn ion and Zn(OH)+.
Organic complex form-Zn form stable complex with organic colloids. This form
is not readily available to plants.

5. Soil pH and Liming
Hydrous oxides of iron and aluminium
Carbonates of calcium and magnesium
Organic matter
Soil submergence
Nutrients other than Zinc
Seasons
Factors affecting Zinc availability

6. Soil pH and Liming
At pH values below 7.7, Zn2+ predominates, but above pH 7.7, ZnOH+ is the
main species, and above pH 9.11 the neutral species Zn(OH)2 is dominant.

7. Adsorption strength - Magnesite (MgCO3) > Dolomite ( CaCO3. MgCO3) >
Calcite (CaCO3 )
Carbonates of Calcium and Magnesium
Fe
Fe
OH
O
OH
+ Zn 2+
O
Fe
Fe
OH
OH
OH
OHH
H
Zn + 2H+
Hydrous oxides of iron and aluminium Zinc is
adsorbed
on hydrous
oxides
Specifically
Carbonates of calcium and Magnesium reduces availability of Zinc.

8. • Zn- organic complexes
• Some root exudates can chelate Zn, increases availability.
• Zinc strongly adsorbed by insoluble organic matter, specially in
alkaline soil.
• Some micro organisms release zinc from insoluble sources.
Soil submergence reduces availability of Zinc in acid soils, due to high
pH and formation of Franklinite ( ZnFe2O4) , Zinc sulphide (ZnS).
In alkaline soils on submergence pH decreases, zinc availability
increases.
Over all effect- submergence reduces zinc availability.
Organic matter
Soluble
Insoluble
Soil Submergence

9. Phosphorus is the most important nutrient which interferes Zn uptake by plants.
Causes-
 Increased plant growth caused by P addition dilutes Zn
concentration in plants ( Dilution effect).
 High P hinders Zn translocation from root to Shoot.
 Disproportionate distribution of Zinc in roots and tops due to
lower mobility of Zinc with in plant system compared to Phosphorus.
 High soil P may reduce VAM development and infection on roots
that may decrease Zn absorption and utilization.
Other cationic micronutrients , Fe2+ , Mn2+ , Cu2+ may suppress Zn2+ uptake,
due to ionic competition in soil, competition for same carrier protein in plants.
Nutrient Interaction

10. Minerals Fertilizers
Gains of Zinc in soils

11. Losses of Zinc from soil
Plant removal
Soil erosion
leaching

12. Zinc Deficiency

13. Alloway, 2008

14. Zinc Deficiency in India
M.V. Singh, 2000
The average level
of Zn deficiency in
Indian soils is
50% and is
projected to
increase to 63%
by 2025.

15. Alkaline soils
Calcareous soils
Leached acidic coarse textured sandy soils
Peat or Muck Soils ( Organic Soils)
Red/ Laterite soils
Application of High does of Phosphatic fertilizer
over liming of acid soils
Soils in which Zinc deficiency may occur
Farming practices that may cause Zinc deficiency

16.  Interveinal chlorosis and reduction in the size of the young
leaves
 In acute deficiency, younger leaves show necrosis and dead spots
 Dicot plants show, short internodes ( rossetting) and decrease in
leaf expansion ( Little leaf)
 Premature leaves drop
 Bud fall off
 Seed formation is less
 Fruits are deformed associated with yield reduction.
 Khaira disease in Rice
 White bud of maize
 Little leaf of cotton
 Mottled leaf of citrus or frenching of citrus
Zinc deficiency symptoms
zinc deficiency symptoms in different crops

17. Zinc deficiency symptoms

18. Relative sensitivity of crops to Zinc deficiency
High Medium Low
Bean Barley Alfalfa
Citrus Cotton Asparagrass
Flax Lettuce Carrot
Fruit Trees ( deciduous) Potato Clover
Grapes Soybean Grass
Hops Sudan Grass Oat
Maize ( Corn) Sugar Beat Pea
Pecan nuts Table beet Rye
Rice Tomato Wheat
Sorghum
Zinc in Soils and Crop Nutrition by- Brian J. Alloway
I

19.  Soil application of Zinc fertilizer
 Foliar Spray
Managing Zinc deficiency

20. Zinc fertilizer applied in soil by Broadcasting or Band
placement.
If broadcasted in soils, then zinc fertilizers should be
thoroughly mixed.
For soils, having low zinc content band placement is
beneficial.
Band placement of Zinc fertilizers is superior over
broadcasting.
Efficiency of zinc fertilizer increases when it is applied with
physiological acidic fertilizers ( Ammonium Sulphate) and
placed in band.
Soil application of Zinc fertilizer

21. Sources Zinc content
Zinc sulphate heptahydrate 21-23 %
Zinc sulphate monohyadrate 33-36%
Zinc oxysulphate 40-55%
Zinc oxide 55-70 %
Zinc nitrate 22%
Zn-EDTA 12-14 %
Zn- HEDTA 9 %
Commonly used zinc fertilizers

22. Rates lower than soil application
Uniform distribution
Almost immediate response
Foliar spray

23. For soil application, dose of Zinc sulphate varies from 10-50
kg/ha depending on crops to be grown.
For fruit tree, Zinc sulphate applied 100 g- 1000 g per tree.
For, plantation crops like Tea, zinc sulphate applied 20 kg/ha
per year.
For foliar spray, dose is varied from (0.1 to 1.5) % ZnSO4 or
Zn-EDTA along with lime.
Application rate
Fertilizers – A text book by R.K.Basak

24. Crop response to zinc fertilization

25. Muthukumararaja and Sriramachandrasekhharan, 2012
Effect of Zinc application on
Dry matter production (DMP) and yield of Rice
Zn
levels
DMP
( Tillering stage)
DMP
( Panicle initiation)
Grain yield
( g/pot)
Straw Yield
(g/pot)
mg/k
g
S1 S2 Mean S1 S2 Mean S1 S2 Mean S1 S2 Mean
0.0 1.59 2.54 2.06 20.44 28.62 24.53 13.68 23.73 18.70 18.01 34.23 26.12
2.5 2.28 3.23 2.75 30.00 38.72 34.72 25.68 25.66 31.17 30.67 53.06 41.86
5.0 2.51 3.46 2.98 36.00 45.87 40.93 32.04 43.02 37.53 35.35 59.74 48.54
7.5 2.45 3.17 2.92 35.50 45.35 40.42 31.36 42.34 36.85 37.03 59.42 48.22

26. Muthukumararaja and Sriramachandrasekhharan, 2012

27. ( t ha-1 )

28. Zn rates
( kg/ha)
Harvest
index
Length of
cob
Number of
rows per
cob
Number of
Kernels
per row
Number
of Kernels
per cob
Thousand grain
weight
( g)
0 47.9 138.8 14.66 27.8 407.0 253.4
0.5 41.9 153.7 15.00 29.2 438 266.1
1.0 42.9 157.2 15.13 31.7 479.5 264.3
1.5 43.2 151.9 15.04 29.4 441.7 275.0

29. Effect of foliar zinc application to maize leaves at 5-6
leaf stage on grain yield

30. Crops Treatments Zn0
( mg/kg)
Zn1
(mg/kg)
Shoot to grain
transfer
coefficient
%Chan
ges over
control
%Chang
es over
control
Grain Straw/
stalk
Grain Straw/
stalk
Zn0 Zn1
Grain Straw/
Stalk
Rice
Local 16.1 35.2 22.3 55.7 0.46 0.43 38.5 58.2
High
yielding
29.1 34.1 40.7 46.4 0.85 0.88 39.9 36.1
Hybrid 20.7 41.9 31.9 75.5 0.49 0.47 54.1 80.2
Wheat
Timely sown 25.0 22.1 36.1 35.0 1.13 1.03 44.4 58.4
Late sown 27.9 22.7 37.4 33.5 1.14 1.12 44.4 47.6
Influence of Zn application on Zinc sequestration potential in grains & straw/stalk
with their shoot to grain transfer coefficients in different cultivars of cereals
Saha et al., (2015)

31. Conclusion
Zinc is a important nutrient element to boost up crop yield.
Widespread deficiency of zinc throughout the world arising as
a big threat to crop production.
Zinc deficiency can lead to several physiological disorders
and ultimately decrease in yield in major food crops like rice,
maize and wheat.
Judicious application of zinc along with suitable crop varieties
can show remarkable increase in economic yield and zinc
content in crops.