- Mn deficiency is largely associated with high pH of the rhizosphere.
- Excessive amount of Manganese reduces Iron uptake in plants.
- Besides an essential micronutrient, Manganese acts as a mild fungistatic agent.
- Manganese deficiency occurs sporadic. Its deficiency in Wheat has emerged and is on the increase in Punjab as a result of the adoption of intensive cultivation of Paddy-Wheat system in place of Maize-Wheat or Groundnut-Wheat system for a period of 7-10 years on highly permeable coarse-textured alkaline soils low in organic matter.
- Powdery mildew incidence in cucumber is reduced with application of low doses of Boron, Copper and Manganese.
- Important in photosynthesis for building of chloroplasts. It helps in carbohydrate and Nitrogen metabolism and their assimilation in the plant.
- Activates (plays catalyst’s role) decarboxylase, dehydrogenase and oxidase systems in Creb’s cycle.
- It seems to act as a two handed (double valence) reception committee of which Zinc and Copper also are the members, to receive other nutrient ions as they enter the plant cell and direct them to their respective positions, where they carry out their functions in plant.
- It is essential for splitting the water molecule (photolysis) during photosynthesis.
- It encourages early growth and maturation of crops
GENERAL DEFICIENCY SYMPTOMS
- Interveinal chlorosis of young leaves. Primary, secondary and tertiary veins remain dark green, exhibiting netted or checkered appearance
- Chlorosis of the leaves appears first near leaf margins and develops in a V-shaped pattern
- In very severe Manganese deficiency, brown necrotic spots appear on the leaves, resulting in premature leaf drop.
- Delayed maturity is another deficiency symptom in some species. Soil Manganese may be less available in dry, well-aerated soils, but can become more available under wet soil conditions when Manganese is reduced to the plant-available form. Conversely, Manganese toxicity can result in some acidic, high-Manganese soils.
SPECIFIC DEFICIENCY SYMPTOMS
- Crinkle leaf spot and shortened internodes in Cotton
- Stem streak and necrosis of Potato
- Internal bark necrosis of Apple
- Leaf spot of Citrus, Tomato, Brinjal, Chilli, Cotton, Grapes (may be Zn deficiency also)
- Premature fruit shedding of Grapes and other fruits (may be Zn/Cu deficiency also)
- Leaf stripe disease of Oat
- Marsh spot of Pea
- Whitish Gray Speckles or Halo Blight of small grains
CAUSES OF MANGANESE DEFICIENCY
- Alkaline soils high in humus or peaty soils with a pH of 6 or more
- Manganese is deficient in dry regions and may be present in toxic amounts in acidic soils
- Calcareous soils, heavily limed soils, sandy soils low in organic matter
- Manganese uptake is adversely affected in soils containing high amount of available Iron.
Oats, Beans, Lettuce, Cucumber, Radish, Soybean, Pea, Sorghum, Cotton, Tobacco, Apple, Peach, Grape, strawberry, Citrus