5. Concentration in the earth’s crust averages 1000 ppm
Indian soils ranges between 92 to 11500 ppm but soils contain 300 to 1600 ppm of Mn.
Manganese when released through weathering of primary rocks will combine with O2, - and
SiO2 to form a number of secondary minerals including pyrolusite (MnO2), manganite
(MnOOH) and hausmannite (Mn3O4)
Forms of manganese are usually expressed as water soluble Mn2+, exchangeable Mn2+,
water soluble and insoluble organically bound manganese, easily reducible manganese and
manganese oxides.
The principal ion species in solution is Mn2+ and its concentration decreases 100 fold for
each unit increase in pH
.
Importence of manganese
6. Factors affecting availability and movement of manganese
Effect of pH and carbonates
Excessive water and poor aeration
Organic matter
Imbalance of metal ions
Interrelationship with other nutrients
Seasonal and climatic effects
Soil microorganisms
Plant factors
7.
8.
9. Functions
Healthy Mn sufficient mature plants contain 20 to 300 ppm of Mn
Mn plays an important role in the photosynthesis and detoxification of
superoxide free radicals
Mn is an integral component of the water splitting enzyme associated
with photosystem II
Mn deficiency is associated with adverse effects on photosynthesis and
O2 evolution
constituent of superoxide dismutase (Mn-SOD)
Mn has a role in TCA cycle in oxidative and non oxidative
decarboxylation reactions with Nicotine Adenine Diamide (NAD)
10. a major contributor to various biological systems including photosynthesis, respiration, and nitrogen
assimilation.
Involved in pollen germination, pollen tube growth.
root cell elongation and resistance to root pathogens.
plays an important role in plant lignin and phenol synthesis
That structural components of the sclerenchyma are less developed under Mn-deficient conditions than under
non-limiting conditions.
Polle and Chakrabarti (1994) found less cell wall material but similar lignin content in Mn-deficient
Involved in activating enzyme-catalysed reactions including phosphorylations, decarboxylations, reductions
and hydrolysis reactions and therefore affects processes such as respiration, amino acid synthesis, lignin
biosynthesis and the level of hormones in plants.
PHYSIOLOGICAL FUNCTIONS
11. Effect of Manganese on plant carbohydrates and lignin content of plant
marschner (2012)
12.
13. Manganese deficiency symptoms, which often look like those of iron deficiency,
appear as interveinal chlorosis (yellow leaves with green veins) on the young leaves, tan, sunken spots that appear in the
chlorotic areas between the veins.
Plant growth may also be reduced and stunted.
Manganese deficiency can occur when the pH of the growing medium exceeds 6.5, because it is tied up and unavailable for
uptake.
Deficiency can also occur from low fertilizer application rates, use of general purpose fertilizers (which typically have
reduced micronutrient contents),
excessive leaching or applying too many iron chelate drenches.
Deficiency symptoms
14. Mn deficient plants contain less than 25
ppm
more severe on middle leaves than on the
younger ones
Interveinal chlorosis in dicotyledons
Grey speck of Oats
Speckled yellow of sugar beet
Marsh spot of peas
Pahala blight of sugar cane
Frenching of tung grass
15.
16.
17.
18. burning of the tips and margins of older leaves or as reddish-brown spots across older leaves.
Severe toxicity may result in spots becoming more numerous and larger, forming patches on
the older leaves.
At pH levels below 5.5, manganese is very soluble and toxicity symptoms are probable,
especially in zonal geraniums, marigolds and New Guinea Impatiens.
Manganese toxicity can occur if the fertilizer application rate is excessive.
Toxicity
19. Corrective measures
Soil application of Mn SO4. 3 H2O (26-28 % Mn) @ 10-25 kg/ha
Mn SO4 H2O (30-32 % Mn) @ 10-25 kg/ha
Application of green manures FYM and other organic manures
21. MANGANESE AS ESSENTIALAND TOXIC ELEMENT FOR PLANTS: TRANSPORT, ACCUMULATION AND RESISTANCE MECHANISMS
Millaleo at al., (2009)
J. Soil Sci. Plant Nutr. 10 (4): 476 - 494 (2010)
22. Upper panel: photobleaching effects on sugar maple leaves exposed to elevated Mn. Lower panel: the influence of Mn
availability and light intensity (1500 and 500 μmol m−2s−1) on the light and dark reactions of photosynthesis (CER, ETR) and
chlorophyll a + bin sugar maple leaves
Manganese phytotoxicity: new light on an old problem
Fernando
23. Assessment of Some Mineral Elements (Ca, Na, K, Mg, Fe, Mn Cu and Zn) and their Nutritional Intake of Two
Traditional Leafy Vegetables: Leaves of Corchorus Olitotorius (Tiliaceae) and Hibiscus Sabdariffa (Malvaceae)
Alexis Drogba Sahore et al.,(2014)
International Journal of Agriculture Innovations and Research Volume 3, Issue 3, ISSN (Online) 2319-1473