Biology
Topic: Mineral Requirements Of Plants
plants require mineral nutrients or elements obtained from the soil in form of solution for good growth and healthy development. The soil is the main source of mineral salts while gaseous elements such as oxygen, hydrogen and carbon are mainly derived from the atmosphere. These elements or plant nutrients are grouped into two classes, depending on the quantity that is required by plants. They are as follows:
1. Macro-nutrients or Major elements: Macro-nutrients are mineral elements or nutrients required in large quantities for healthy growth of plants. Examples of macro-nutrients are nitrogen, phosphorus, potassium, magnesium, calcium, oxygen, hydrogen, carbon, sulphur and iron. These macro-nutrients are sometimes called essential elements.
2. Micro-nutrients or Trace elements: Micro-nutrients are mineral elements or nutrients required in small quantities for healthy growth of plants. Examples of micro-nutrients are zinc, copper, boron, molybdenum, cobalt, chlorine and manganese. When a plant lacks any of these elements, it shows certain signs and these signs are called deficiency symptoms. These micro-nutrients are sometimes called non-essential elements.
The functions and deficiency symptoms of these elements are stated below:
1. Nitrogen
Functions
1. Aids protein synthesis
2. Formation of nucleic acid
3. Formation of chlorophyll
4. Constituents of all enzymes and protoplasm
Deficiency symptoms
1. Stunted growth
2. Yellow leaves
3. Small or reduced leaves
2. Phosphorus
Functions
1. Aids protein formation
2. Formation of co-enzymes
3. Controls nuclear division
4. It helps in root development
5. Fruit formation and maturity
Deficiency symptoms
1. Poor growth
2. Leaves and stem turn reddish brown
3. Poor root development resulting in logging.
3. Potassium
Functions
1. It aids cell formation.
2. It aids synthesis of carbohydrate.
3. It activates various plant enzymes reactions.
4. Cell membrane formation.
Deficiency Symptoms
1. Weak slender stems
2. Delayed growth
3. Brown colour at margin of leaves.
4. Calcium
Functions
1. Formation of cell walls
2. Activates certain enzymes
3. Neutralises organic acids
4. Normal growth of root tips
Deficiency Symptoms
1. Weak slender plants
2. Poor root development
3. Stunted growth
5. Magnesium
Functions
1. Chlorophyll formation
Deficiency symptoms
1. Yellowing of leaves
2. Poor growth
6. Sulphur
Functions
1. Protein synthesis.
Deficiency Symptoms
Stunted growth and slender stem, yellowing of leaves (chlorosis).
7. Iron
Functions
Chlorophyll formation
Deficiency Symptoms
Yellowing of leaves (chlorosis) and stunted growth.
8. Manganese
Functions
Activation of some enzymes
Deficiency symptoms
Die-back of shoots.
9. Copper
Functions
Constituent of respiratory enzymes
Deficiency symptoms
1. Poor growth
2. Pale green colour of leaves
10. Zinc
Functions
Activation of enzymes
Deficiency Symptoms
Poor leaf formation.
11. Boron
Functions
Transport of calcium and sugar
Deficiency Symptoms
Shoot turns brown.
12. Molybdenum
Functions
1. Aids nitrogen fixation
2. Metabolism of nitrate
Deficiency Symptoms
1. Retarded growth.
2. Necrosis of leaf tissue.
13. Silicon
Functions
Cell wall formation
Deficiency Symptoms
Poor growth.
Culture Solution
A culture solution is a solution containing all the major elements required by plants for their normal growth and development. Examples of culture solutions usually prepared in the laboratory are: Knop’s culture and Sach’s culture solution. Both culture solutions are called complete culture solutions because they contain all the major elements necessary for plant growth.