The great importance of plant hormones


Today’s agriculture is not about sowing a seed, adding water and compost, and hoping to pick up a large, perfectly flavored red pepper. Unfortunately, we have reached levels where we have to find arduous efforts to improve productions. In this , plant hormones have a vital role , either applied by us or generated naturally by the plant. In any case, today it’s time to discover its peculiarities.


Phytohormones are natural substances produced by the plant cells of our plants. They occur at strategic times and places (basically, when the plant wants to 🙂). Therefore, these plant hormones, produced at a specific moment in the life of the plant and applied to a specific point of the plant, produce a certain action and regulate physiological phenomena.

As a curiosity to say that if, for example, the plant wants to stimulate a specific part of its tissue, the cells do not have to produce said plant hormones in that specific place, but can move freely through the xylem and phloem .


We currently know and have at our disposal 6 plant hormones. However, we can also find other compounds that, although not considered as phytohormones, produce or stimulate the plant physiologically. This is the case of sistemin, strigolactone, salicylates, oxilipine, polyamine, oligosaccharins, etc.

Some plant hormones can improve the ripening and homogenization of the fruits


Where we can find it:  in leaves, stems and green fruits before ripening.


Auxins (indoleacetic acid) act as plant growth regulators. What they do, in basic terms, is increase the size of the cells, so it translates into a larger size of the plant. It also delays the fall of leaves, induces gravitropism, promotes fruit growth and the growth of lateral roots, etc.

Where we can find it:  in the seed embryo, in young leaves, meristematic tissues of apical buds, etc.


We have already talked more fully about cytokinins  so we are not going to say anything new. Its function in the plant is to stimulate cell growth. If the auxins increased their size, what this phytohormone does is increase the number of cells.

Where we can find it:  in the roots, although they can be transported to other areas of the plant.


Ethylene stimulates the ripening of the fruits and causes the leaves to fall. There is great curiosity regarding its discovery. In the 19th century, it was observed that the trees located just above the streetlights were irretrievably defoliated. This led them to the conclusion that the street lamps produced ethylene which caused abscission of the leaves .

Where we can find it:  in the tissue of ripe fruits, in the nodules of the stems, leaves and flowers in the senescence stage.

Many farmers will know it as ethephon . The hydrolysis of this compound is what produces ethylene, and it has the following functions:

  • Slow down plant growth and increase tolerance to cold.
  • Stimulate the sprouting of bulbs.
  • Rupture of dormancy in seeds.
  • Favor the earliness and uniformity in the ripening of the fruits.
  • Stimulate the opening of the cotton capsules.

Advancement of ripening in persimmon with the application of ethephon


Where we can find it:  in the meristems of apical buds, in the roots, in young leaves and in embryos.


Many are unaware of these phytohormones and remain or are familiar with the previous ones. However, brassinosteroids play a very important role in plants, especially to solve problems related to environmental or biotic stress.

They have growth action on cells, their cell division and differentiation, which is why they contribute, in an important way, to improve the performance of cultures.

A lack of these brassinosteroids would pose very serious problems for the plant, such as dwarfism, poor rooting (and future sudden plant death), loss of fertility, underdevelopment of leaves and stems, etc.


The application of plant hormones to the crop has its weight in specific moments of the plant where an improvement of the energy assimilation of the plant is required. For example, this is the case of the application of amino acids, an easily available energy source of the plant, used to solve specific plant situations, such as environmental stress (hail, high or low temperatures), critical stages (germination, flowering, fruit set, etc.).

Many times, these plant hormones are added to other components that provide an extra supply of energy to the plant. For example, carboxylic acids, disaccharides, vitamins, etc. are added.

The carboxylic acids have been studied for its potential to prevent cracked in plants (with total loss of market), to increase the organoleptic quality and increase in fruit postharvest life, among other things.

The disaccharides  (sucrose, maltose, lactose, etc.) are carbohydrates that the plant produces the fotosíntensis and increases the quality of fruits and provide energy for the growth of vegetative parts in the plant.

For example, a compendium of cytokinins, auxins and gibberellins plus some of the aforementioned compounds can act as follows:

  • Cruciferous and compound: to increase the size and uniformity of the heads.
  • Cucurbits: to improve the initial development of the plant.
  • Peppers:  to increase the life of the plant, reduce aging and alleviate the effects of stress.
  • Potato: to increase the size of the tubers at the time of tuberization.
  • Tomato: to increase the development of the fruits and their tie.

In this regard, the dosage is very important. A higher or lower amount of a certain plant hormone induces a different response.

A product that, for example, contains auxins (ANA + ANA AMIDA) does not produce the same response in different cultures. Although normally this group of plant hormones serve to stimulate flowering at specific times of the crop. In crops such as peppers , it improves flower setting (the formation of fruits), and in stone or pip fruit trees, it stimulates vegetative activity or prevents fruit from falling.

In conclusion, plant hormones can be very interesting applied to crops when they need a strong response at times when the climate, fertilizer or soil are not favorable. The market for vegetable products also means that the application of these compounds increases over the years (demand for greater earliness, flavor, size, etc.). However, we could say that it is a “prize” for cultivation, as when a bag of goodies is given to a child :). The more sugar added to the coffee, the sweeter it will be. As simple as that.

And you, do you think it is necessary to add these plant hormones to the fertilizer plan of any crop?

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