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| What Nutrients Do |
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Deficiency Symptoms |
Calcium
Calcium functions in plants include strengthening cell
walls to prevent their collapse, enhancing cell division
and plant growth, protein synthesis, carbohydrate movement,
and balancing cell acidity. All Ca in plants is taken
up from the soil. |
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Poor root or tip growth is a common symptom of Ca deficiency.
In severe cases, the growing point dies. Calcium deficient
roots often turn black and rot. Young leaves and other
new tissue develop symptoms because Ca is not translocated
within the plant. New tissue needs Ca pectate for cell
wall formation, so Ca deficiencies cause gelatinous leaf
tips and growing points.
Calcium deficiencies seldom show up in the field because
secondary deficiency effects such as high acidity usually
limit growth first. |
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Magnesium
In plants, Mg is essential for the production of the green
pigment chlorophyll. Chlorophyll is essential for photosynthesis,
the conversion of sunlight into plant food (carbohydrate
synthesis). Each chlorophyll molecule contains about 7
percent Mg. Magnesium is also known to be essential for
many of the energy reactions constantly taking place in
plant cells. |
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Magnesium deficiency symptoms first appear on lower (older)
leaves, generally, because Mg is translocated within the
plant. They show a yellowish, bronze or reddish color,
while leaf veins remain green. Magnesium deficiency may
also be accentuated by high K rates or by high availability
of ammonium-N when the soil contains borderline Mg. |
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Sulfur
Sulfur is a part of every living cell and is a constituent
of two of the essential amino acids which form proteins.
Other functions of Sulfur in the plant:
- Helps develop enzymes and vitamins
- Promotes nodulation for N fixation by legumes
- Aids in seed production
- Is necessary in chlorophyl formation although it
is not a constituent of chlorophyll
Unlike Ca and Mg, which are taken up by plants as cations,
S is aborbed primarily as the sulfate (SO4)
anion, it can also enter plant leaves from the air as
sulfur dioxide (SO2) gas. |
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Plants deficient in S show a pale green coloring of the
younger leaves, although the entire plant can be pale
green and stunted in severe cases. Leaves tend to shrivel
as the deficiency progresses.
Sulfur, like N, is a constituent of proteins, so deficiency
symptoms are similar to those of N. Nitrogen deficiency
symptoms are more severe on older leaves, however, because
N is a mobile plant nutrient and moves to new growth.
Sulfur on the other hand, is immobile in the plant, so
new growth suffers first when S levels are not adequate
to meet plant need. This difference is important in distinguishing
between the two, particularly in early stages of a deficiency.
Plants deficient in S can be thin-stemmed and spindly.
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