Plants Also Utilize Calcium, Magnesium, and Sulfur

PLANTS ALSO UTILIZE CALCIUM, MAGNESIUM, AND SULFUR 

Both calcium and magnesium are absorbed by plants as the positively charged calcium and magnesium ions, Ca2+ and Mg2+, and sulfur is absorbed as the negatively charged sulfate ion, SO 2-. Most topsoils contain enough of these ions for adequate plant growth. 

Calcium ions are essential for building cell walls. Once absorbed by the plant, calcium ions are relatively immobile that is, they do not travel well from one part of the plant to another. The plant therefore is not so capable of reallocating calcium supplies in times of need. This is why new-growth zones, such as the tips of roots and stems, are most susceptible to calcium deficiencies. The results are twisted and deformed growth patterns. 

Most of the sulfur in plants occurs in proteins, especially in the amino acids cysteine and methionine. Other essential compounds that contain sulfur are coenzyme A, a compound essential for cellular respiration and for the synthesis and breakdown of fatty acids, and the vitamins thiamine and biotin. Sulfur can be absorbed by leaves as gaseous sulfur dioxide, S02, an environmental pollutant released from active volcanoes and from the burning of wood or fossil fuels. 

Magnesium ions in the green pigment chlorophyll are vital to photosynthesis. 

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