Today we are going to talk about magnesium, a macronutrient as important as it is forgotten.
Magnesium (Mg) is the most forgotten macronutrient in the fertilisation process. It is agronomically one of the most important macronutrients in plant growth, due to its contribution to the mechanism of root formation, photosynthesis and chlorophyll.
The key functions of magnesium are:
- Photophosphorylation
- C02 fixation during the process of photosynthesis
- Chlorophyll formation
- Protein synthesis
- Phloem transport
- Leaf photo-oxidation
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Magnesium deficiency causes poor growth and reduced yield. If there is a reduction in magnesium, there is a reduction in the production of enzymes, mainly RIBULOSE-1.5-BIPHOSPHATE CARBOXYLASE, an important part of the photosynthesis process.
The most common symptom of magnesium deficiency is the yellowing of old leaves. The degree of deficiency also depends on the intensity of sunlight, as high light intensities increase interveinal chlorosis and at the same time the plants show necrosis. Studies and trials have concluded that plants growing in conditions with higher light intensity require a higher supply of magnesium.
Due to problems of Mg leaching in high rainfall areas and its interaction with Aluminium (Al), Mg deficiency in acid soils is a very common and growing problem. It is well documented that plants employ an adaptive mechanism in acid soils: the roots release organic acids. These organic acids plus Al ions form organic acid-Al complexes, which are no longer phytotoxic. It is also well known that Mg is essential for the release of organic acids by the root ,and makes the modification of Al possible. This shows that Mg plays a major role in alleviating Al toxicity.
THE IMPORTANCE OF MAGNESIUM
- Sufficient levels of Mg are required to maximize the transport of carbohydrates from “Source” organs to demand organs (such as root and seeds).
- Sufficient levels of Mg are required to maximize the transport of carbohydrates from “source” organs to demand organs (such as root and seeds).
- Maintaining an adequate supply in late-stage magnesium fertilisation is also important for minimising the production of photo-toxic substances that cause damage to chloroplasts.
- Magnesium deficiency leads to poor root growth, which results in low uptake of other nutrients and water, especially in conditions of low soil fertility.
- A fertilisation rich in Magnesium in plants, helps the synthesis of sugars and proteins for essential amino acids.
Magnesium EXCESS
- Magnesium toxicity in plants can lead to problems related to the absorption of other nutrients. Most commonly, the plant loses the opportunity to have the correct levels of Calcium and Potassium, which are highly sensitive nutrients.
- They affect the cationic relationships related to the antagonism in which they participate. This can have some specific antagonistic effect such as Mg/Ca.
- In very acidic and poorly aerated soils, assimilable magnesium can reach very high levels and plants absorb it in quantities greater than their needs, achieving varying degrees of toxicity.
- Excess magnesium is difficult to occur. What can happen due to an excess of this mineral in our plants is that it prevents the absorption of nitrogen
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