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Plant Hormones: Everything You Need To Know In One Place

Plant Hormones: Everything You Need To Know In One Place

Hormones trigger many changes in people, but did you know plants contain hormones as well? 

Hormones make things happen. Consider them as biochemical messengers that carry information from part of the plant to another. And, like spicy sauce, a small amount makes a big difference. Hormones are often present in tiny doses, but boy can they steal the show.  

So, keep reading to find out about the fascinating effects hormones have on plant growth and development.

Let’s Start!

What are Plant Hormones?

Plant hormones, also known as phytohormones, are single chemical transmitters produced by plants that control key cell functions such as embryogenesis, stress resistance, synapse formation, disease defense, regulation of body part size, vegetative growth, and reproductive evolution.

They essentially supervise crucial operations that take the plant from seed to mature plant, then back to seed to reproduce the next generation.

Abscisic acid, auxin, cytokinin function, ethylene, and gibberellins were the five predominant plant hormones by the mid-20th century. Researchers have also added brassinosteroids, jasmonates, salicylates, and strigolactones to the list in recent years.

The activity of plant hormones is determined by their synthesis, which is influenced by the antagonistic processes of conjugation and degradation. Transport also contributes to the regional buildup of plant hormones. Scientists do not completely grasp the basic processes that regulate several hormones.

In general, we know that plant hormones signal by attaching to sensors. Some of these sensors are transmembrane proteins, so when a hormone attaches to them, they change conformation.

In other receptors, hormones operate as "molecular glue" to allow two different proteins to bind, starting the actions that occur because of this contact. Protein phosphorylation, proteolysis, and transcription are downstream signaling steps that support a variety of processes and essential cellular functions inside the plan.

Having said that, let’s take a thorough analysis of the five main types of Plant Hormones.

Plant Hormones And Their Functions.

Plant hormones are mainly of five types: auxin, gibberellin, cytokinin, ethylene, and abscisic acid. These hormones can affect plant development either collectively or individually.


Have you ever wondered why a plant bends toward the sun? It has something to do with auxin in the stem. Darwin and his son were also interested in it. They didn't know what was driving plants to bend toward the light. It wasn't until the late 1920s that scientists discovered Auxin.

Because auxin is involved in cell growth and expansion, plants typically generate it in regions that are actively developing, such as the stem. This is when things get interesting. Auxin travels in a plant through just one route — downhill from the top to the bottom, similar to a one-way road from the stem tip to the roots. It is the only plant hormone that can do so.

As a result, the concentration of auxin is highest at the top of the plant and lowers as you move closer to the roots, controlling the general form of the plant and helping keep the major stem of a plant the leader.

Have you ever witnessed the apex of a single clipped tree stem grow over 20 new stems? Because auxin maintains apical dominance, it inhibits many lateral buds and branches from sprouting on the stem's side. When you prune the plant's main stem, the source of the auxin is gone, and no single stem becomes dominant — it abolishes apical dominance.

Auxin has several functions, the most significant of which is to encourage growth; if a plant rarely generates auxin, it will die. As you can see, auxin is crucial.

There are both natural and synthetic forms of auxin:

Some of the functions of the Auxin Hormones are as follows:

  • Cell elongation of stems and roots.
  • It induces Parthenocarpy, or the formation of fruit without fertilization, for example, in tomatoes.
  • Prevents leaves, flowers, and fruits from falling prematurely.
  • It is useful for initiating roots in stem cuttings and grafting.
  • Promotes blooming, for example, in pineapple.
  • We often use it as a herbicide to destroy noxious weeds of dicot plants while causing no harm to monocot plants.
  • Contributes to cell division and xylem differentiation.


Gibberellin has some of the same effects on plants as auxin, but it is a completely distinct hormone. Gibberellins were first found in Japan. 

Gibberella Fujikuroi, a fungus, infected rice plants, causing them to grow too tall and topple over. The infecting fungus released a substance that encouraged rice plant growth. Plants naturally create versions of these compounds, which were discovered later.

Gibberellins serve a crucial function in many phases of plant growth, but their claim to fame is that they make stems longer. Gibberellins encourage stem growth between nodes. It elongates the internodes, which are the places on a stem where a leaf attaches.

The lack of gibberellin is most visible in dwarf and rosette plants, where there is a tiny space between nodes on a stem, and it groups the leaves around the plant's base.

Some of the functions of the Gibberellin Hormones are as follows:

  • It encourages bolting or the abrupt extension of internodes right before blooming in rosette plants such as cabbage and beets.
  • Postpones Senescence.
  • Induces Parthenocarpy.
  • It can reverse Dwarfism through stem lengthening.
  • It induces certain plants to become male, such as cannabis.
  • In the endosperm of sprouting cereal grains and barley seeds, it promotes the development of hydrolytic enzymes such as lipase and amylase.
  • Breaks the dormancy of seeds.

If you are looking to use Gibberellin Hormones on your plants, Gibberellic Acid is the safest and the most effective form.


Who thought fish might help with the development of a plant hormone? Aged herring sperm DNA can aid cell division. We know the chemical responsible for this as kinetin. Soon later, researchers discovered a chemical present in plants that had the same biological action as kinetin; it sped up plant cell division when cultured with auxin.

The chemical is known as cytokinin, and it is involved in cell division and the formation of new plant parts such as roots and shoots. Cytokinins are created in the root apical meristems and migrate up the stem through the xylem, hitching a ride with water. The movement of cytokinins is passive - no energy is required.

Some of the functions of the Cytokinin Hormones are as follows:

  • It stimulates lateral and adventitious shoot development and is used in culture to begin shoot growth.
  • Aids in the removal of apical dominance caused by auxins.
  • Stimulate chloroplast development in leaves.
  • Encourages nutrient mobilization and postpones leaf senescence.

Kinetin is an example of Cytokinin


Have you ever observed that putting a fully ripe, brown banana next to a bunch of green bananas causes the unripe bananas to ripen and turn yellow considerably faster? What causes this to happen?

The brown banana communicates with the green bananas via ethylene, a hormone. Ethylene is a plant hormone that influences plant ripening and rotting. Because it occurs as a gas, it is a particularly intriguing plant hormone. There is no other plant hormone that is gaseous. Plants can produce ethylene in almost any part and can diffuse through its tissue outside the plant, and travel through the air to affect a completely different plant.

Some of the functions of the Ethylene Hormones are as follows:

  • It speeds up the ripening of fruits.
  • Controls leaf epinasty.
  • Breaks the dormancy of seeds and buds.
  • Accelerates the elongation of petioles and internodes.
  • Promotes leaf and blossom senescence and abscission.
  • Increases the absorption surface by stimulating root development and root hair production.
  • In monoecious plants, it stimulates femaleness.
  • Formation of apical hooks in dicot seedlings.

Abscisic Acid

When our bodies require water, we become thirsty. The "thirst signal" shows that we require water. When a plant requires water, such as during a drought, it does not have many alternatives. A rain dance is essentially out of the question.

Plants create abscisic acid, a chemical messenger, to inform the rest of the plant that it is water-stressed. Abscisic acid is produced in droughted leaves, roots, and developing seeds and can move up and down a plant stem in the xylem or phloem, sounding the alarm.

Some of the functions of the Abscisic Acid Hormones are as follows:

  • Causes leaf and fruit abscission.
  • It inhibits seed germination.
  • Induces leaf senescence.
  • Accelerates dormancy in seeds, which is important for storage.
  • Stimulates stomatal closure to prevent transpiration during water stress.  

That's a quick rundown of the five key plant hormones: auxin, gibberellin, cytokinin, ethylene, and abscisic acid. Remember that hormones are powerful small chemical messengers, yet they would lose their potency if they lingered and accumulated in plant tissues. As a result, they degrade and are replaced over time.

You can find abscisic acid with us

Final Thoughts

A rising corpus of research shows that phytohormones do not have separate, solitary roles, but collaborate to control a variety of processes. There is a lot of cross-talk between them, and a single process may arise from the activity of many plant hormones.

With that, we have reached the end of this article. If you are looking for an online store to buy Agrochemicals and Plant Hormones, do check out Ases Chemicals for amazing prices and super fast delivery.

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