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

There are four types of naturally occurring plant hormones. These are auxin, gibberellins, cytokinin and abscisic acid. The physiological effect of plant hormones on growth and development are as follows:

1. Auxin: It promotes cell elongation and thus promotes growth of a plant part.

2. Gibberellins: Like auxin, it also helps in the growth of the stem.

3. Cytokinin: It promotes cell division and thus promotes growth.

4. Abscisic acid: It Inhibits growth and is responsible for shedding of older parts.