Question

What is plant hormone? describe types of plant hormone biosynthesis and role inplants in hindi?

Answer 1

Plant hormones are chemicals in plants that regulate cellular processes. They are usually found in small amounts throughout the plant. These hormones are very important as they determine many different attributes of a plant. Plant hormones can be natural or synthetic.
Plant hormones are also known as phytohormones.

There are 5 types of Plant hormone :-
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1) Auxines :-

Auxines r group of plant hormone synthesised in apical meristem of root nd shoot tips . It promotes cell elongation, root formation , cell division , Respiration , physiological process .

2) Gibberellins :-

Gibberellins stimulates stem Elongation nd seed germination & flowering the maximum concentration of gibberellins found in Fruit nd seeds .

3) Cytokinins :-
Cytokinins chemical which promotes cell division . they r produced in diving cell throughout the plant , In mature plant cytokinins r present in root tips nd r transported to shoot .
They help in breaking dormancy nd regulating phloem transport .

4) Ethene :-
It promotes Growth nd ripening of fruits . It keeps in breaking dormancy in buds nd seeds .

5) Abscisic Acid :-
It promotes dormancy in seeds nd seeds thus inhibits growth . It also promotes closing of stomata nd thus effects wilting of leaves .

Answer 2

Types of Phytohormones.

The major types of plant hormones which are involved in the control and coordination in plants are as follows:

(i) Auxins are the group of plant hormones synthesised at the shoot-tip of the plant body .

• It promotes cell elongation, root formation, cell division, respiration and other physiological processes like protein synthesis, water uptake and protoplasmic permeability.

• Auxins also play an important role in the development of seedless fruits.

(ii) Gibberellins stimulate stem elongation, seed gennination and flowering.

• The maximum concentration of gibberellins is found in fruits and seeds.

(iii) Cytokinins are produced in dividing cells throughout the plant

• In mature plants, cytokinins are produced in the root tips and are transported to the shoots.

• Cytokinins promote cell division and also helps in breaking the dormacy of seeds and buds and regulate the phloem transport.

• Cytokinins delay the ageing in leaves and promote the opening of stomata.

(iv) Abscisic Acid (ABA) : It is a growth inhibitor which reverses the growth-promoting effects of auxins and gibberellins.

Its effect include wilting of leaves.

• It causes dormancy of seeds, tubers and bulbs.

• It promotes the closing of stomata and is responsible for the loss of RNA, proteins and chlorophylls.