Question

Why is abscisic acid also known as stress hormone?

Answer 1

Hint:The major role of the abscisic acid (ABA) is to regulate abscission and dormancy and it has wide ranging effects on plant growth and development. Abscisic acid (ABA) acts as a general plant growth inhibitor and also a plant growth inhibitor of whole plant metabolism. Abscisic acid (ABA) acts as an antagonist to gibberellic acid.

Complete answer:
In order to answer this question, we need to know about the plant hormones. So that we can know about abscisic acid and why it is a stress hormone.

Plant hormones include auxin, gibberellins, cytokinins, ethylene, abscisic acid .
Plant functioning under stress is affected by the plant hormone.
There are mainly five plant hormones.
(a) auxin: They helps in initiate rooting in stem cuttings, an application widely used for plant cultivation
(b) Gibberellins: They produce a wide range of physiological responses in plants and also, they delay senescence .
(c) Cytokinins: They help overcome the apical dominance and they promote nutrient mobilisation which helps in the delay of leaf senescence
(d) Ethylene: It breaks seed and the bud dormancy and also initiates germination in the peanut seeds, sprouting of potato tubers
(E)Abscisic acid: It stimulates the closure of the stomata in the epidermis and increases the tolerance of the plant to various kinds of stresses. It promotes the seed dormancy and ensures the seed germination under favourable conditions.

According to the question,
Abscisic acid stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kinds of stresses.
So, it is called the stress hormone.

Note: For every phase of growth like differentiation and development of plants one or other PGR has some role to play such roles could be complementary and antagonistic.