Question

Give a brief account of auxins.

Answer 1

1. Auxins are plant growth hormones produced mainly in the growing tips of stems and roots (apical meristems) and in young leaves. They promote cell elongation, resulting in stem growth.
2. They promote cell elongation and increase stem length.
3. They are responsible for phototropism and geotropism by causing unequal growth on different sides of the plant.
4. They promote the formation of adventitious roots in stem cuttings.
5. They help in fruit development and may induce parthenocarpy (development of seedless fruits).
6. They prevent the premature fall of leaves and fruits (abscission).
7. Examples: Indole-3-acetic acid (IAA) is the principal natural auxin. Synthetic auxins include IBA (Indole Butyric Acid) and NAA (Naphthalene Acetic Acid).