Plant Growth Regulators: Types of Plant Growth, Primary and Secondary Growth (For CBSE, ICSE, IAS, NET, NRA 2022)

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Types of Plant Growth

Types of Plant Growth

Primary and Secondary Growth

  • The meristematic cells increase the length of the plant body, which is the primary growth.
  • Increase in the diameter of the plant body by the division of the secondary meristem is called the secondary growth.

Limited Growth

This means after reaching to a certain size the plant parts stop growing.

Unlimited Growth

This means growth from germination till death.

Vegetative Growth

  • This means the production of stem, leaves, and branches.
  • There is no production of flowers.

Reproductive Growth

At this stage flowering occurs.

Factors Affecting Plant Growth

Factors Affecting Plant Growth


  • All plants require light and CO2 for photosynthesis.
  • Apart from manufacturing of food, light is also useful for flowering and fruiting.
  • The growth of plants is retarded during the winters when the days are short.


  • 90 % of the plant body is composed of water.
  • Water helps in keeping the plant hydrated.
  • Plants cannot survive without water.


  • Processes such as transpiration, photosynthesis, and germination get speed up due to temperature.
  • The growth of plants gets slowed down due to low temperatures.


  • Some of the micronutrients required by plants are Nitrogen, potassium, calcium, magnesium, Sulphur, and phosphorus.
  • Deficiency of even a single nutrient can result in stunted growth of the plant.

Plant Growth Retardants

  • The synthetic compounds, which reduce the plant growth.
  • Some of the important growth retardants are Phosphon-D, AMO-1618, Paclobutrazol, etc.


Q 1. What are some of the important characteristics of Plant Growth Regulators?


Some of the important characteristics of Plant Growth Regulators are:

i) Ripening of fruits.

ii) Seed dormancy.

iii) Formation of leaves flowers and stems.

iv) Elongation and differentiation of cells.

v) They can accelerate as well as retard the rate of growth in plants.

Q 2. What are the two types of Plant Growth Regulators?


Two types of Plant Growth Regulators are:

i) Plant Growth Promoters

ii) Plant Growth Inhibitors

Q 3. What are the main factors affecting Plant Growth?


There are four factors affecting Plant Growth:

i) Light

ii) Water

iii) Temperature

iv) Nutrients

Q 4. What are some of the Plant Growth Regulators?


Some of the Plant growth Regulators are:

i) Auxins

ii) Gibberellins

iii) Cytokinins

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