Plant hormones: basics

In short: Plant hormones are chemical messengers that control growth, development, and plant responses to environmental stimuli, similar to hormones in the human body. They often act even at very low concentrations.

In more detail: Unlike animal hormones, plant hormones aren’t produced in specialised glands but in various tissues.

In detail

• Auxins: These hormones promote cell growth and control the orientation of plant parts towards light, known as phototropism.
• Gibberellins: They promote stem elongation and play an important role in breaking seed dormancy.
• Cytokinins: These hormones promote cell division and counteract auxins in controlling growth directions.
• Ethylene: As a gaseous hormone, it controls fruit ripening and leaf shedding in autumn, among other things.
• Abscisic acid: This hormone helps plants respond to stress like drought by closing the leaf stomata.
• Interaction: Plant hormones rarely act in isolation but influence each other within complex signalling networks.
• Agricultural application: Synthetic plant hormones are used deliberately, for example to control fruit ripening or combat weeds (pflanzen-aufbau-und-wachstum, enzyme-grundlagen).