Ethylene

The term “Phytohormones” also refers to Plant hormones. Phytohormones are organic compounds made by higher plants naturally that control growth or other physiological processes at a location far from the origin of synthesis and are only active in very small amounts. Because these hormones are produced in plants, Thimmann (1948) proposed the term “Phytohormone.” Among the hormones produced by plants are Auxins, Gibberellins, Cytokinins, Ethylene, Growth inhibitors, and Growth retardants. The first hormones found in plants were Auxins, followed by the discoveries of Gibberellins and Cytokinins.
Characteristics
1. The word hormone is Greek in origin and means to set in action. Cellular division, growth, and gene expression are all affected by plant hormones.
2. they are naturally produced within plants. Although fungi and bacteria also create very similar compounds that can impact plant growth,
3. Plant hormones are chemicals, not nutrients, that, in little doses, encourage and impact the growth, development, and differentiation of cells and tissues.

Types of Plant Hormones
It is generally agreed that there are five main categories of plant hormones, some of which can have a wide range of chemical compositions from one plant to the next.
The five main categories are:
a) Auxin
b) Gibberellin
c) Cytokinin
d) Ethylene
e) Absisic acid