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What are hormones and what do they do?

Hormones are organic molecules that can influence the physiology of both plants and animals. In plants, hormones are produced naturally and can have a positive impact on their growth and development. The effectiveness of hormones depends on their concentration and the plant's sensitivity to them. This article will discuss the five main plant hormones: Auxine, Gibberellic Acid, Cytokinine, Ethylene, and Abscisine Acid.


Auxine is mainly produced in young leaves, young seeds, pre-flowering buds, and the stem. It has a positive influence on cell stretching, cambium activity, and bud formation. Auxine transport occurs slowly at a rate of 1cm/hour and requires significant energy. Inactivation of Auxine occurs through binding with sugars or oxidation.

Auxine plays a crucial role in root growth and is often found in root stimulators. It works better when combined with Cytokinine.

Gibberellic Acid​

Gibberellic Acid is primarily produced in young leaves, although roots can also produce it. It is transported from the roots to the leaves and branches. When added to the roots, Gibberellic Acid suppresses the formation of lateral roots while accelerating cell stretching in other parts of the plant.

Gibberellic Acid can also help seeds germinate faster and increase the production of female seeds. However, excessive use of Gibberellic Acid can be harmful to plants.


Cytokinine is found in high concentrations in young plant material, including leaves and roots. It activates cell stretching, triggers flowering, and germination, slows plant aging, and protects membranes from oxidation.

The presence of both Cytokinine and Auxine in high concentrations can lead to the development of buds, stems, and leaves, while lower concentrations encourage the growth of complete plants. Inactivation of Cytokinine occurs through binding with sugars or oxidation.


Ethylene is produced within the plant and also by fungi and bacteria. Its transport occurs through intercellular spaces, and inactivation happens due to oxidation. Ethylene can also be released as a gas into the atmosphere.

Under normal conditions, Ethylene production slows down cell stretching and thickens roots and stems. However, excessive Ethylene can deform and even kill plants, making proper balance essential for healthy growth.

Abscisine Acid​

Abscisine Acid slows down cell division, cell stretching, and bud formation. It acts as an antagonist of Gibberellic Acid, Auxine, and Cytokinine, slowing down plant growth and flowering. Abscisine Acid is produced mainly in older leaves and chlorophyll.


Understanding plant hormones and their functions is essential for proper plant care and growth. However, it is crucial not to experiment with pure hormones unless you are confident in what you are doing. Balancing the levels of these hormones is critical for maintaining healthy plants and preventing damage or stunted growth.
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