Question

Name various plant hormones. Also give their physiological effects on plant growth and development.

Answer 1

There are five major types of plant hormones: auxins, gibberellins, cytokinins, abscisic acid, and ethylene.

1. Auxins -  When the growing parts of a phototropic plant detect sunlight, auxins (synthesized at the shoot tips) help the cells grow longer. When light falls on one side of the plant, the auxins generally diffuse towards the shaded side of the shoot. They also helps in root formation, apical dominance, inhibition of abscission and fruit growth.
2. Gibberellins - They are produced in the roots of a plant. They promote stem elongation by promoting cell division in the inter-nodal region.
3. Cytokinins - They promotes cell division. Therefore, they are present in greater concentration in those areas of the plants where rapid cell division occurs. For example, the tip of the shoot.
4. Abscisic acid -  It promotes seed dormancy by inhibiting cell growth. It is involved in the opening and closing of stomata. It is also responsible for the shedding of leaves.
5. Ethylene - It regulates fruit ripening. It is produced during the ripening of fruits.