Plant hormones, also known as phytohormones, are chemical compounds produced by plants that regulate various aspects of plant growth and development, including embryogenesis, organ size, pathogen defense, stress tolerance, and reproductive development
. They occur in extremely low concentrations and are derived from secondary metabolism
. There are five major groups of plant hormones: auxins, cytokinins, gibberellins, ethylene, and abscisic acid
. These hormones play a crucial role in various processes such as:
- Cell division and enlargement
- Flowering
- Seed formation
- Dormancy and abscission
Plant hormones can be categorized into two types based on their action:
- Plant Growth Promoters : These hormones stimulate growth and development processes, such as cell division, enlargement, and flowering
- Plant Growth Inhibitors : These hormones slow down or inhibit growth and development processes, such as cell division, enlargement, and flowering
Plant hormones are produced in almost all parts of the plant and are transmitted to various parts where they are perceived, and the response may occur far away from the site of hormone synthesis
. Hormones can act synergistically or individually, and their roles can be complementary or antagonistic
. Synthetic plant hormones are often used instead of naturally occurring versions because they can cause greater or longer-lasting responses and be less susceptible to degradation in the plant
