Soil Science - Sameti.org

Soil Science
Functions of Magnesium
i. Magnesium helps in formation of chlorophyll and thus imparts dark green colour to leaves. It is
indispensable for photosynthesis by plants.
ii.
iii.
iv.
It is usually needed by plants for formation of oils and fats.
It regulates the uptake of nitrogen and phosphorus from the soil.
Magnesium may increase crop resistance to drought and disease.
v. It plays a part in the production of carbohydrates, proteins, fats and vitamins and helps in the
translocation of carbohydrates and fats.
vi.
In oil producing crops, it plays an important role in synthesis of oils and fats.
Symptoms under Deficient Supply
i. Visual symptoms of an inadequate supply is the yellowing of the older leaves. It is known as
chlorosis. Acute deficiency of magnesium also causes premature defoliation. Magnesium
deficiency symptoms are usually observed on older leaves.
ii.
iii.
6. Sulphur
In maize, the leaves develop intravenial white strips; in cotton they change to purplish red, veins
remaining dark green; in soyabean they turn yellowish and in apple trees, brown patches (blotches)
appear on the leaves.
The veins of chlorotic leaves remains green.
Sulphur exists in two important essential amino acids-methionine and cystenine, which are also
component of protein. It has specified role in initiating synthesis of protein. Sulphur is an important
nutrient for oil seeds, cruciferae, sugar and pulse crops. As such these crops grow best on sulphur rich
soil. It is an essential constituent of many proteins, enzyme and certain non-volatile compound such as
mustard oil. Salm-Horstmar has established sulphur as essential element for plant in 1851.
Function of Sulphur
i. Sulphur is involved in the formation of chlorophyll and thereby encourages vegetative growth.
But it is not a constituent of chlorophyll.
ii.
iii.
iv.
Sulphur forms an important constituent of straw and plant stalks.
Pungent odour of onion and garlic is due to the presence of sulphur compound.
It promotes the nodule formation on the root of leguminous plant.
v. It hastens root growth and stimulates seed formation.
vi.
It is essential for the synthesis of certain amino acids and oils. It can be called as master nutrient
for oil seed production.
Symptoms under Deficient Supply
i. The young leaves turn yellow and the root and stems become abnormally long and develop
woodiness.
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