Plant Deficiencies
The
correct diagnosis of nutritional deficiencies is important in
maintaining optimum plant growth. The recognition of these symptoms
allows growers to fine tune their nutritional regime as well as minimize
stress conditions. However, the symptoms expressed are often dependent
on the species of plant growth, stage of growth or other controlling
factors. Therefore, growers should become familiar with nutritional
deficiencies on a crop-by-crop basis.
Record keeping and photographs are excellent tools for assisting in the diagnosis of nutrient deficiencies. Photographs allow growers to compare symptoms to previous situations in a step-by-step approach to problem solving. Accurate records help in establishing trends as well as responses to corrective treatments.
Nitrogen (N) Restricted
growth of tops and roots especially lateral shoots. Plants
become spindly with general chlorosis of entire plant to a light
green and then a yellowing of older leaves which proceeds
toward younger leaves. Older leaves defoliate early.
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Phosphorous (P) Restricted
and spindly growth similar to that of nitrogen deficiency.
Leaf color is usually dull dark green to bluish green with
purpling of petioles and the veins on underside of younger
leaves. Younger leaves may be yellowish green with purple
veins with N deficiency and darker green with P deficiency.
Otherwise, N and P deficiencies are very much alike.
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Potassium (K) Older
leaves show interveinal chlorosis and marginal necrotic spots
or scorching which progresses inward and also upward toward
younger leaves as deficiency becomes more severe.
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Calcium (Ca) From
slight chlorosis to brown to black scorching of new leaf tips
and die- back of growing points. The scorched and die-back
portion of tissue is very slow to dry so that it does not
crumble easily. Boron deficiency also causes scorching of new
leaf tips and die-back of growing points, but calcium
deficiency does not promote the growth of lateral shoots and
short internodes as does boron deficiency. |
Magnesium (Mg) Interveinal
chlorotic mottling or marbling of the older leaves which
proceeds toward the younger leaves as the deficiency becomes
more severe. The chlorotic Interveinal yellow patches usually
occur toward the center of leaf with the margins being the last
to turn yellow. In some crops, the interveinal yellow patches
are followed by necrotic spots or patches and marginal
scorching of the leaves. |
Boron (B) Slight
chlorosis to brown to black scorching of new leaf tips and die-
back of the growing points similar to calcium deficiency. Also
the brown and black die- back tissue is very slow to dry so that
it can be crumbled easily. Both the pith and epidermis of
stems may be affected as exhibited by hollow stems to roughened
and cracked stems. |
Sulfer (S) Resembles
nitrogen deficiency in that older leaves become yellowish green
and the stems thin, hard and woody. Some plants show colorful
orange and red tints rather than yellowing. The stems,
although hard and woody, increase in length but not in
diameter. |
Iron (Fe) Starts
with interveinal chlorotic mottling of immature leaves and in
severe cases, the new leaves become completely lacking in
chlorophyll but with little or no necrotic spots. The
chlorotic mottling on immature leaves may start first near the
bases of the leaflets so that in effect the middle of the leaf
appears to have a yellow streak.
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Manganese (Mn) Starts
with interveinal chlorotic mottling of immature leaves and in
many plants it is indistinguishable from that of iron. On
fruiting plants, the blossom buds often do not fully develop
and turn yellow or abort. As the deficiency becomes more
severe, the new growth becomes completely yellow, but in
contrast to iron necrotic spots usually appear in the
interveinal tissue. |
Zinc (Zn) In
some plants, the interveinal chlorotic mottling first appears on
the older leaves and in others, it appears on the immature
leaves. It eventually affects the growing points of all
plants. The interveinal chlorotic mottling may be the same as
that for iron and manganese except for the development of
exceptionally small leaves. When zinc deficiency onset is
sudden such as the zinc left out of the nutrient solution, the
chlorosis can appear identical to that of iron and manganese
without the little leaf.
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Copper (Cu) Leaves
at top of the plant wilt easily followed by chlorotic and
necrotic areas in the leaves. Leaves on top half of plant may
show unusual puckering with veinal chlorosis. Absence of a
knot on leaf where petiole joins the main stem of plant
beginning about 10 or more leaves below growing point.
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Molybdenum (Mo) These
deficiency symptoms in legumes are mainly exhibited as
nitrogen-deficiency symptoms because of the primary role of
molybdenum in nitrogen fixation. Unlike the other
micronutrients, molybdenum-deficiency symptoms are not confined
mainly to the youngest leaves because molybdenum is mobile in
plants. The characteristic molybdenum deficiency symptom in some
vegetable crops is irregular leaf blade formation known as
whiptail, but interveinal mottling and marginal chlorosis of
older leaves also have been observed. |
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