SYMPTOMS OF
INTERVEINAL CHLOROSIS
When a leaf displays interveinal
chlorosis, the veins in that leaf will
look a normal shade of green while
the leaf tissue in between the veins
(called mesophyll) is a pale green
or even yellow when the chlorosis
is more severe. Chlorophyll is the
chemical or biomolecule within a
plant that absorbs sunlight and
uses its energy to create carbohy-
drates. These carbohydrates then
become a source of energy for the
plant. The process that creates
them using CO 2 and water is called
photosynthesis. Chlorophyll is the
heart and soul of photosynthesis,
which in turn is the powerhouse
of the plant. This molecule is key
to plant health, and we need to be
aware of it if our plant begins to
exhibit interveinal chlorosis.
Chlorophyll has magnesium as its
central metal ion and the organic
molecule that it bonds to is called a
porphyrin. There are several steps
(biosynthesis) within the plant that
must occur to create a chlorophyll
biomolecule. Ultimately, these
steps lead to the creation of either
a hemeprotein or chlorophyll. The
science behind the evolution of the
chlorophyll molecule is complex,
but suffice it to say that manganese, iron,
and zinc all have key roles in its creation.
Manganese is an enzyme activator during
chlorophyll production and a structural
component of the chloroplasts where photo-
synthesis occurs. Zinc is a key nutrient in
supporting the creation of chlorophyll, and a
lack of iron will interfere with it as well. There
are debates regarding the symptoms and
determination of which nutrient deficiency
has caused a plant’s chlorosis. These yellow-
ing symptoms look very similar. Other symp-
toms such as necrotic leaf spots caused by
low zinc levels can help determine which may
be the culprit.
Chlorophyll is the heart and soul of
photosynthesis, which in turn is the
powerhouse of the plant.”
EVALUATING CHLOROSIS
A key point to remember when evaluating
chlorosis is that the lack of iron, zinc, or
manganese may cause the chlorotic condi-
tion in a plant. Very often, it is assumed that
only the lack of iron is causing this problem,
so iron is added as a cure. Sometimes,
the result is only a very slight change in
symptom or no change at all because it
is one of the other micronutrients that are
deficient for the adequate production of
chlorophyll. Then again, there may be an
issue with the root system that is causing the
micronutrients to fail assimilation.
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