Functions and deficiency of Manganese and molybednum

1. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Nutrients : Forms, Occurance, Functions and Deficiency Symptoms
Essential Elements: Forms, Occurance,
Functions and Deficiency Symptoms
Krishna Aryal
Asst. Professor (Soil Science)
Krish.aryal2014@gmail.com
1

2. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Nutrients : Forms, Occurance, Functions and Deficiency Symptoms 2
Manganese content of soil
• Exists in soil sol a Mn2+ & Mn4+.
• Its availability increases with decreasing soil pH. Concentration in soil is
20-300 ppm
• Mostly they occur as a coating of soil particles.
• Deposited in the cracks & veins of rocks & minerals
• Mn containing minerals includes Manganite MnO (OH), Pyrolusite MnO2
Braunite Mn2O3 .
Manganese
Forms and occurrence
• Absorbed by plants roots as manganous ion (Mn2+).
• Normal conc. of this element in plants from 20-50 ppm.

3. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Nutrients : Forms, Occurance, Functions and Deficiency Symptoms 3
Functions of Mn in plants
• It helps in the formation of chlorophyll.
• Involves in photosynthesis, particularly in evolution of O2.
• Essential constituent of nitrate reductase & hydroxylamine reductase.
• Activation of enzymes(Mallic dehydrogenase, isocitrate dehydrogenase)
participating in the Kelvin cycle.
• Accelerate germination & maturity.

4. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Nutrients : Forms, Occurance, Functions and Deficiency Symptoms 4
Deficiency of Mn in plants
• Immobile in plant and def. starts in the
younger leaves.
• Interveinal chlorosis on the younger leaves;
no sharp distinction between veins and
chlorotic areas
Oats - Gray specks / streaks
Peas - Marsh spot
Sugarbeet - speckled yellow
Sugar cane - Pahala blight - midrib pale
green and white.
• Reduced lignifications of stem wood in trees
causing lateral branches to weep.

5. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Nutrients : Forms, Occurance, Functions and Deficiency Symptoms 5
Molybednum content of soil
• Its availability to plants is frequently low because of extremely small amt.
of MoO4
2- in soil sol.
• Content of Mo in most ag. soils is usually between 0.6- 3.5 ppm with an
average Mo content of 2.0 ppm & an average available molybdenum
content of 0.2 ppm.
• Mo largely occurs in the soil as an oxycomplex (MoO4
2- ).
Molybednum
Forms and occurrence
• Also known as ultramicronutrient or nano nutrient as it is needed in the
smallest amount by plant.
• Mo content of plant material is <1 ppm;
• Available to plant as MoO4
2- form.

6. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Nutrients : Forms, Occurance, Functions and Deficiency Symptoms 6
Functions of Mo in plants
• Essential component of enzyme nitrate reductase in plants. (Nitrogen
assimilation)
• Structural component of nitrogenase (N –fixation by root nodule &
bacteria)
• Essential role in Fe absorption & translocation in plants.
• Involved in conversion of inorganic P to organic form in plants.
(Phosphorus assimilation)

7. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Nutrients : Forms, Occurance, Functions and Deficiency Symptoms 7
Deficiency symptoms of Mo in plants
• As Mo is immobile in the plant, its
deficiency is manifested on younger
leaves.
• Deficiency symptoms resembles N def
but occurs in younger leaves.
• Leaves become pale and eventually wither.
• Restricted growth
• Inhibit N fixation in legumes
• Yellow spot of citrus leaves.

8. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Nutrients : Forms, Occurance, Functions and Deficiency Symptoms 8
• Cauliflower exhibits whiptail (leaves get twisted elongated)
• Cabbage shows cupping, veins become purple, leaves become necrotic
and malformed along the margins.
• Tomato – chlorotic mottling – old leaves roll inwards along leaf margin.

9. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Nutrients : Forms, Occurance, Functions and Deficiency Symptoms 9