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Do you know the building blocks for a good size and quality of your fruit?

Effect van bladvoeding op de vruchtmaat

The quality and size of your fruits are important and decisive factors for the price you get for them. Let’s take a closer look at the nutrients that determine the quality and size of the fruits.

How does a fruit actually develop? Understanding this process provides us with the keys on how to respond and improve it.


Fruit growth: a combination of 2 factors

Fruits develop in 2 phases:

  • Intensive cell division: The fertilization of the flowers is followed by a period of cell division. This period is intense but quite short.
  • Cell elongation: After the cell division, the period of cell growth starts. In fruit, we call this the cell elongation.

The final size of the fruits depends on both factors:

  • The number of cells that is formed during cell division is the basis and creates the potential for large fruits.
  • The more cells that can grow and swell in the second phase, the greater the final fruit size will be.

Which nutrients stimulate cell division and cell expansion?

Boron, calcium and potassium are the 3 nutrients that should not be absent during fruit formation. They each have a specific function.



  • Boron for good flower induction and flower formation

First of all, the fruit must be formed correctly. It is therefore important that the plant has good and specially fertile flowers. Boron (along with calcium) plays here a leading role. It ensures that cell division proceeds in an orderly manner. Problems with the cell division during flower formation unfortunately has an direct effect on their quality.

Boron therefore ensures good flower induction and formation. As a result, the flowers will be of good quality and fertile, also due to the good quality of the pollen.

  • The positive effect of boron on the young fruits

After the fertilization of the flowers, boron also stimulates the cell division of the young fruits. It prevents possible deformities and ensures homogeneous fruits. Boron will thus determine the final growth potential of the fruits.

  • Boron promotes the transport of calcium

Boron guarantees fertile flowers and ensures that the fruits have sufficient seeds, in for example, pit fruit, such as apple and pear. These seeds in turn produce plant hormones that stimulate and facilitate the transport of calcium to these fruits. Why calcium is important for the fruits you can read further in this blog.

  • Boron facilitates the transport of sugars

Boron plays, just like potassium (see below), a role in sugar transport towards the fruits. How?

  • It improves the membrane permeability making it easier for the sugars to end up in the phloem.
  • In addition, boron also forms complexes with sugars specifically to improve the evacuation of these sugars from the leaves to the fruits. This makes the fruits sweeter.



  • Calcium for strong cell walls

We mentioned earlier that calcium together with boron assures that the cell division in the flowers and the fruits proceed correctly.

In addition, it is important to incorporate calcium into the cell walls of the newly formed cells during the period of cell division. It ensures strong and elastic cell walls. The cells will then be stronger during cell elongation and remain intact, ensuring the fruit quality.



  • Potassium is very important for cell growth.

To illustrate the importance of potassium, a small technical clarification:

Potassium stimulates the formation of a large central vacuole. This is a compartment in the cytoplasm of the cell that is enclosed by a membrane.

The vacuole can take up to 80-90% of the cell volume. The formation of this vacuole determines the final size of the cells and thus also of the fruits.

Potassium promotes the accumulation of dissolved substances in this vacuole, so that it can swell by osmotic pressure.

  • Potassium also facilitates the transport of sugars

Another important function of potassium: it facilitates the transport of sugars. Potassium ensures that all the metabolites as a result of the photosynthesis in the leaves, end up in the phloem, so that they can move easily to the fruits.

  • Finally, potassium is also important for good coloring.


Plant hormones also influence the growth of fruits

Hormones that promote cell division and cell elongation are:

  • cytokinins
  • gibberilins
  • auxins

It is therefore interesting to stimulate and optimize the endogenous production of these plant hormones. Zinc for example plays an important role in the production of auxins. Ensuring the correct nutrition of this element is therefore also important.
Chelal Noor will also promote the endogenous production of auxins. On the other hand is it interesting to apply seaweed extracts to obtain a good fruit size because of their natural high cytokinins concentration.

Is everything still balanced?

Pay attention to the nutritional balance of your crop.

It is important to know what the plant needs, but we also have to be aware of excesses. A good plant nutrition is pre-eminently a balanced nutrition in which we take into account the right proportions between all the different nutrients.

  • Use nitrogen sparingly

Nitrogen is an essential element for almost all processes in the plant and should not lack. Be careful though, if you use too much nitrogen, the plant will enter in a vegetative growth mode and neglect the development of the fruits.

Effects on the fruits:

  • less sweet
  • - softer
  • drop prematurely
  • ripening and coloring is more difficult

The plant will then channel its energy to the formation of new shoots and leaves instead of to the fruits.

  • Use potassium economically

Although we wrote earlier in this blog that potassium is important for good fruit quality, we still have to be careful with excessive potassium fertilization. When high potassium applications are done, antagonistic effects of this element can occur on the calcium nutrition of the fruits. The fruits then absorb less calcium, putting their quality at risk.

Our findings to the test

Recent trials have proved the validity of these theoretical explanations. You will find the results of these field trials on our trial page. Or click below:

Improving fruit size on apricots


Do you have questions or remarks after reading this blog? Feel free to contact us. We'd love to hear from you.

More information about the cell:
The living cell - Round trip in a microscopic world, Cristian de Duve
Nature and Technology 1987, ISBN: 90-70157-59-4 - November 2006