Auxin: What is auxin, types and its application in agriculture

Auxin is a phytohormone, that is, a plant hormone

More and more people are aware that plants are also living beings that breathe, feed and reproduce. However, it is difficult to imagine the existence of specific hormones for plants. Yes, vegetables have their own hormones, also called phytohormones. One of them is auxin, which we are going to talk about in this article.

Auxins themselves and their importance in plant growth were first described by Fritz Warmolt Went, a botanist and mycologist from the Netherlands. If you want to know more about these hormones, I recommend that you keep reading.

What is auxin?

Auxin is the most studied plant hormone

Auxin is the most studied plant hormone

When we speak of auxins, we refer to a specific group of phytohormones, or plant hormones, whose purpose is to regulate the growth of plants. To achieve this, they basically cause elongation of cells. The place where they carry out their synthesis are the meristematic regions belonging to the apex of the stems. From there, the auxins move towards other areas belonging to the plant, especially towards the base in which a concentration gradient is established in this way. A curious fact: it has been found that the synthesis of auxins takes place in various organisms such as fungi, algae, bacteria and higher plants. In addition, most of the time it is related to stages of intense growth.

Thanks to the studies that have been carried out on auxins, it has been possible to establish first the presence and then the importance of plant hormones or phytohormones. Currently there is extensive scientific information on plant hormones that even surpasses the knowledge about others. Due to this, the understanding that there is today about the action of hormones in vegetables is very precise. Auxins participate in the regulation of various physiological processes in plants, along with cytokinins and gibberellins. However, there are more compounds with the same capacity.

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As expected, humans have learned to take advantage of this discovery in agriculture. There are several processes for which farmers use these phytohormones:

  • Acceleration of vegetable growth.
  • Promotion of the initiation of adventitious roots.
  • Promotion of fruit set and flowering.
  • Prevent the fruits from falling prematurely.

Auxin in agriculture

Auxin has several applications at the agricultural level

Auxin has several applications at the agricultural level

The sector that has benefited the most from studies related to auxins is agriculture. Next we are going to comment on its applications at the agricultural level.

Asexual propagation

Today, one of the main uses of auxins is when it comes to propagate plants asexually, either through cuttings, stakes, etc. Due to its stability and low mobility, the most commonly used auxin in these cases is indole butyric acid, or IBA. 1-Naphthaleneacetic acid or ANA is also commonly used, but it is more mobile, causing its effects to be less consistent at times. In tissue culture micropropagation, auxins 2,4-D and ANA are often used to stimulate cell division and induce root formation in undifferentiated callus.

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Fruit holding

Another very common use of auxins is increase fruit holding under certain conditions and species. For example: The application of naphthoxyacetic stimulates the binding of tomato fruits when it is in bloom under cold and night climates. However, under normal conditions the use of this auxin has no effect. As for other crops, naphthoxyacetic may have no results or be inconsistent. However, mixing it with other hormones can favor the binding of the fruits of some species.

Fruit growth

Also in the growth stage of the fruits, auxins can be used to increase and stimulate their final size. However, this effect has only been achieved with 4-CPA and in some very well defined plant species, such as seedless grapes. In contrast, other species have only resulted in foliage deformations, irregularity in fruit size and delayed ripening.

Fruit drop

Auxin is used for many processes in crops

Auxin is used for many processes in crops

There are crops that require fruit thinning, also called fruit thinning. It is a cultural practice that consists of eliminating excess fruits. In some cases it is necessary for the quality and size of production to increase and thus avoid major fluctuations. By means of the auxin called 1-naphthaleneacetic acid, the fall of the fruits can be induced. Basically the purpose is to partially remove the young fruits so that there is less competition and thus increase the size of the fruits that remain on the tree, such as apples and pears. It also aims to reduce all the negative effects that the fruits could have in the following annual cycle, during the formation of flowers. This is usually the purpose in apple and olive trees.

Fruit retention

By contrast, auxins can also intervene in the inhibition of fruit drop when they are in a mature stage. To achieve this effect, auxin must be applied to fruits that are about to ripen. These can drop prematurely if they release ethylene naturally. Normally, this technique is used to harvest apples, lemons, oranges and grapefruits and the auxins used are ANA or 2,4-D.

Auxin as a herbicide

Some hormones such as 2,4-do or Picloram they have a herbicidal effect on some plants when their doses are high. Its effects include growth arrest, folded leaves, and increased stem thickness.

Other uses of auxin

Apart from the effects that we have mentioned so far, auxins can have more in crops, such as the following:

  • Growth of flower parts
  • Stimulation of photosynthate flow
  • Delayed organ maturation

I hope this article has helped you understand plants a little better and gain more knowledge about the world of botany. Every day new features are being discovered whose applications have yet to be tested.

Auxin: What is auxin, types and its application in agriculture

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