Question

What are the different plant growth hormones?

Answer 1

Plant growth hormones:

1. It regulates the growth and differentiation of plants.
2. These are also called phytohormones.
3. It also regulates other physiological activities at the site of synthesis or away from it.
4. Some of the hormones that cause plant growth are auxins, gibberellins, cytokinins, ethylene, and abscisic acid.

Auxin:

1. It causes elongation of stems and roots.
2. It inhibits the growth of lateral buds, a phenomenon that is called apical dominance.
3. It controls the abscission layer in plants and prevents the premature drop of fruits.
4. It causes parthenocarpy i.e. development of seedless fruits without fertilization.

Gibberellins:

1. It also causes elongation of the stem.
2. It breaks the dormancy of buds and tubers.
3. It increases the fruit size in plants.

Cytokinins:

1. It induces cell division.
2. It breaks the dormancy of seeds.
3. It causes apical dominance.
4. It causes a delay in senescence.

Ethylene:

1. It inhibits the elongation of stems and roots.
2. It accelerates the abscission of leaves, flowers, and fruits.
3. It retards flowering in most plants but induces flowering in pineapple, mango, and many other plants.

Abscisic acid:

1. It is a growth inhibitor.
2. It causes bud dormancy as well as seed dormancy.
3. It accelerates senescence and abscission.
4. It controls transpiration in plants.