Magnesium is absorbed by plants in their Mg2 + cationic form. It is a constituent of the chlorophyll molecule. It is studied together with calcium and potassium (although it is less abundant) and constitutes between 0.3-0.5% of the dry weight.

The magnesium that is part of chlorophyll only constitutes 10-15% of the total. The rest works as an enzymatic activator and co-factor of almost all the enzymes involved in the plant’s energetic metabolism. Also, in the metabolism of carbohydrates, in the synthesis of nucleic acids, proteins and in transcription. Therefore, it can be said that magnesium plays a double role in plants: on the one hand structural (forming part of the chlorophyll molecule) and on the other, functional (as an enzyme activator).

In terms of phloem circulation it is associated with potassium, so its role in fruit development is important.

Magnesium deficiency: Mg is a very mobile element and its shortage is characterized by an interveinal chlorosis of the oldest leaves. This is because the cells closest to the leafs’ veins retain more chlorophyll than the rest.

In terms of Mg deficiency, you may also observe:

  • A greater need for the element highly lit conditions.
  • An increase in the problems arising in acid soils leached with Al toxicity in case of Mg deficiencies. Mg (and Ca) have the ability to release organic molecules that form stable bonds with Aluminum.
  • Greater difficulty in transporting sugars through the phloem of the plant. Inhibition of the transport of sucrose by the plant.
  • Less radicular proliferation than under conditions with normal Mg levels.

Therefore, it is necessary to maintain good Mg levels in the plant to prevent the photoassimilates transport from being ideal for the plant’s drains.

It can be observed, in relation to possible Mg deficiencies, bad root formations in tobacco, bean, foliar chlorosis in coffee, and in tomato, especially bluish-yellow interveinal stains.

Excess magnesium: As in the case of K and Ca, excess Mg can produce an indirect deficiency of K and Ca by interfering between them.