MAGNESIUM UTILIZATION BY PLANTS
Magnesium is generally taken up by plants in lower quantities than calcium or potassium. The content of magnesium in plant tissues is usually about 0.5% of the dry matter. Cation competitive effects in uptake are of particular importance for magnesium as such effects frequently lead to magnesium deficiency in the field.
High potassium levels in the soil can result in magnesium deficiency in plants. Conversely, data has also shown that high magnesium contents may occur in plants supplied with a low level of potassium nutrition. These higher magnesium contents cannot be explained simply in terms of a concentration effect resulting from a lower rate of growth but probably originate directly from enhanced magnesium uptake from low levels of potassium nutrition.3
The transport of magnesium in plants is similar to that of calcium. Higher levels of magnesium are usually found in the older leaves when compared to the younger leaves. Magnesium, like calcium, moves upwards in the transpiration system. In contrast to calcium; however, magnesium is also mobile in the phloem system.
The most well known role of magnesium in the plant is its occurrence at the center of the chlorophyll molecule (see Figure 1). The fraction of the total plant magnesium associated with chlorophyll, however, is relatively small and only about 15 to 20%. In addition to its function in the chlorophyll molecule, magnesium is required in other physiological processes. One major role of magnesium is as a cofactor in almost all enzymes activating phosphorylation processes (combining an inorganic compound with phosphorous). Magnesium also has an essential function as a bridging element for the aggregation of ribosome subunits, a process that is necessary for protein synthesis.4
Magnesium deficiency symptoms differ between plant species although some general characteristics are apparent. Since magnesium is mobile in the plant, deficiency begins in the older and then moves to the younger leaves. Intervenial yellowing or chlorosis occurs and in extreme cases the areas become necrotic. Another characteristic particularly of plants exposed to strong sunlight is their generally withered appearance. The look is similar to that of potassium deficiency where the water content of the plant is disturbed. Individual leaves suffering from magnesium deficiency, however, are stiff and brittle and the intercostal veins are twisted. Magnesium-deficient leaves often fall prematurely.5 Plants that are inadequately supplied with magnesium often show a delay of the reproductive phase.
CORRECTING MAGNESIUM DEFICIENCIES WITH METALOSATE® MAGNESIUM
The research data generated over the years in respect to Metalosate Magnesium consistently indicates that Metalosate Magnesium applied in combination with other Metalosate products has very positive results. Some examples of these instances are listed below.
These represent only two of many instances where a combination of Metalosate products including Metalosate Magnesium resulted in significant yield increases for the growers.
1. Mengel, K., & Kirkby, E.A. (2001) Principles of Plant Nutrition (5th ed.) (p. 411). Dordrecht: Kluwer Academic Publishers.
2. Mengel, K., & Kirkby, E.A. (2001) Principles of Plant Nutrition (5th ed.) (p. 412). Dordrecht: Kluwer Academic Publishers.
3. Mengel, K., & Kirkby, E.A. (2001) Principles of Plant Nutrition (5th ed.) (p. 413). Dordrecht: Kluwer Academic Publishers.
4. Marschner, H. (2002) Mineral Nutrition of Higher Plants (2nd ed.) (p. 279). San Diego, CA: Academic Press.
5. Mengel, K., & Kirkby, E.A. (2001) Principles of Plant Nutrition (5th ed.) (p. 419). Dordrecht: Kluwer Academic Publishers.