Plant Hormones

Plant Hormones

Following five hormones are found in plants –

1. Auxins:

• Auxins was discovered by Darwin in the year 1880.
• This is the hormone which controls the growth of plants. Its formation takes place in the apical parts of the plants.

Its main functions are –

• It prevents the separation of the leaves.
• It destroys the straws.
• It saves the crops from falling.

2. Gibberellins:

It was discovered by a Japanese scientist Kurosava in the year 1926.

• The growth harmone gibberellins was first extracted from fungus in 1938 by Yabuta and Sumiki.

Its main functions are –

• It turns the dwarf plants into long plants. It helps in creating flowering.
• It helps in breaking the dormancy of plant.
• It motivates the seeds to be sprout.
• It increases the activity of cambium in the wooden plants.
• Large sized fruits and flowers can be produced by its scattering.

3. Cytokinins:

It was discovered by Miller in the year 1955 but  it was named by Lethem.

Its main functions are –

• It naturally works in coordination with auxins.
• It help in cell division and development in the presence of auxins.
• It help in breaking the dormancy of seed.
• It is helpful in making RNA and protein.

4. Abscisic Acid or ABA:

This hormone was initially discovered by Carnes and Adicote and later on by Waring.

Its main functions are –

• This hormone is against to the growth.
• It keeps the seeds & bud in dormant condition.
• It plays main role in separation of leaves.
• It delays the flowering of long day plant.

5. Ethylene:

This is the only hormone found in gaseous form. In 1962 Burg proven it as hormone.

Its main functions are –

• It helps in the ripening the fruits.
• It increases the number of female flowers.
• It motivates the separation of leaves, flowers and fruits.
• Gas used for artificial ripening of fruit is ethane or ethylene.

Florigens:

It is formed in leaves but helps in blooming of the flowers. Therefore, it is also called flowering hormones.

Traumatin:

This is a type of dicarboxylic acid. It is formed in injured cells by which the injury of the plant is healed.

• The concept of tissue culture was introduced by Haberlandt.
• The plant growth regulator are small, simple molecules of diverse chemical composition. They are indole compound, adenine derivative carotenoids and terpenes.
• Growth of plant without soil is known as hydroponics.
• For the growth of plant sodium is not an essential component.
• Growth of plant is measured by device crescograph invented by – Jagadish Cahndra Bose.