Question

What are Hormones ?
How many types of hormones in plants?
Explain.​

Answer 1

$\huge \mathfrak{Answer}$

Initial research into plant hormones identified five major classes: abscisic acid, auxins, cytokinins, ethylene, and gibberellins. This list was later expanded, and brassinosteroids, jasmonates, salicylic acid, and strigolactones are now also considered major plant hormones.

Answer 2

${\large{\underline{\underline{\bf{Hormones \: in \: Plants:-}}}}}$

Hormones control the growth and developement of a plant. They are organic substances, other than nutrients which increase, decrease or modify the physiological processes in Plants.

${\large{\underline{\underline{\bf{Types \: of \: Plant\:Hormones}}}}$

There are five types of plant hormones are:-

◉ Auxin

◉ Gibberellins

◉ Cytokinins

◉ Abscisic acid

◉ Ethylene

✮ ${\underline{\bf{Auxin}}}}}$ ➸ Auxins are universally present in plants and their highest concentration is in the growing tips of shoots, leaves and roots. IAA(Indole Acetic Acid) is the principal natural auxin found in all plants.

✮ ${\underline{\bf{Gibberellins}}}}}$ ➸ Gibberellins are widely distributed in nature. Roots and young leaves close to the shoot tip are the major sites of GA synthesis. Gibberellins promote growth of internodes of stem by cell elongation.

✮ ${\underline{\bf{Cytokinins}}}}}$ ➸ Cytokinins are the growth substance which act primarily on cell division and have little effect on extension growth. Cytokinins promote cell division. Cytokinins also act as antisenescene factor by delaying the breakdown of chlorophyll in leaves.

✮ ${\underline{\bf{Abscisic \:acid}}}}}$ ➸ Abscisic acid is a growth inhibitor even at a very low concentration. Abscisic acid acts on growing regions by inhibiting both cell division and cell extension. It delays the opening of both vegetative and flowering buds.

✮ ${\underline{\bf{Ethylene}}}}}$ ➸ Ethylene is a potent growth regulator. it occurs in high concentration in leaves, dormant buds and flowers undergoing senescene. It plays an important role in the natural ripening of fruits.

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