Plant Physiology 2011
The chief source is the soil.
Plants absorbs it either in the form of nitrate or
Some bacteria and heterocysts containing blue green
algae fix the nitrogen of the atmosphere.
Nitrogen is an essential constituent of different
proteins and nucleic acids
The chlorotic symptoms in leaf.
A light red cast can also be seen on the veins and petioles.
The older mature leaves gradually change from their normal
characteristic green appearance to a much paler green.
As the deficiency progresses these older leaves become
uniformly yellow (chlorotic).
Branching is reduced in nitrogen deficient plants resulting in
short, spindly plants.
The yellowing in nitrogen deficiency is uniform over the entire
leaf including the veins.
In some plants the underside of the leaves and/or the petioles
and midribs develop traces of a reddish or purple color.
Sulphur is available to plants in the form of soluble
sulphate of soil.
Sulphur is the constituent of amino acids ( cystein and
methionine), vitamin (B1), co-enzyme A and volatile
The characteristic odour of crucifer plants, onions,
garlic and tropeolae is due to sulphur as a constituent
of volatile oils.
Sulphur affects an increase in nodule formation in
root of leguminous plants.
Sulphur adversely affects chlorophyll synthesis.
leaves show a general overall chlorosis while still retaining
some green color.
The veins and petioles show a very distinct reddish color.
sulfur deficiency are very similar to the chlorosis found in
However, in sulfur deficiency the yellowing is much more
uniform over the entire plant including young leaves.
The reddish color often found on the underside of the leaves
and the petioles has a more pinkish tone and is much less vivid
than that found in nitrogen deficiency.
with advanced sulfur deficiency brown lesions and/or necrotic
spots often develop along the petiole, and the leaves tend to
become more erect and often twisted and brittle.
as H3PO4 and HPO4.
It promotes healthy root growth and fruit ripening by
helping translocation of carbohydrates.
It is an essential participating in the skeleton of
plasma membrane, nucleic acids, many coenzymes
and organic molecules such as ATP and other
It plays an important role in the energy transfer
reaction and in oxidation reduction process.
Phosphorus-deficient leaves show some necrotic
A major visual symptom is that the plants are dwarfed
Some species such as tomato, lettuce, corn and the
brassica develop a distinct purpling of the stem,
petiole and the under sides of the leaves.
Under severe deficiency conditions there is also a
tendency for leaves to develop a blue-gray luster.
In older leaves under very severe deficiency
conditions a brown netted veining of the leaves may
derived from stone or chalk rock contains a larger percentage
of calcium carbonate.
Calcium is the chief constituents of plants as calcium pectate of
the middle lamella of the cell wall.
It provides a base for the neutralization of organic acid and is
also concerned with the growing root apices.
It also acts as an activator of ATPase, some kinase,
phospholipids and succinate dehydrogenase.
It is essential for fat metabolism.
formation of membrane, carbohydrate metabolism, nitrate
assimilation, binding of nucleic acids with proteins.
Calcium-deficient leaves show necrosis around the
base of the leaves.
Classic symptoms of calcium deficiency include
blossom-end rot of tomato (burning of the end part of
tomato fruits), tip burn of lettuce and death of the
growing regions in many plants.
All these symptoms show soft dead necrotic tissue at
rapidly growing areas, which is generally related to
poor translocation of calcium to the tissue.
potassium is widely distributed in soil minerals.
Its utilisation in plant is concerned with
synthesis of nucleic acid and chlorophyll
oxidative and photophosphorylation
translocation of solutes etc.
Deficiency symptoms potassium
Leaves show marginal necrosis (tip burn),
others at a more advanced deficiency status show
necrosis in the interveinal spaces between the main
veins along with interveinal chlorosis.
The onset of potassium deficiency is generally
characterized by a marginal chlorosis progressing into
a dry leathery tan scorch on recently matured leaves.
magnesium occurs as carbonate fairly similar to that of
It is a constituent of chlorophyll and, therefore, essential
for the formation of this pigment.
It acts as a phosphorous carrier in the plant, particularly in
connection with the formation of seeds of high oil
contents which contain compound lecithin.
Magnesium is essential for the synthesis of fats and
metabolism of carbohydrates and phosphorous.
It is required to combine two subunits of ribosomes.
The Mg deficient leaves show advanced interveinal
chlorosis, with necrosis developing in the highly chlorotic
In its advanced form, magnesium deficiency may
superficially resemble potassium deficiency.
In the case of magnesium deficiency the symptoms
generally start with mottled chlorotic areas developing in
the interveinal tissue.
The interveinal laminae tissue tends to expand
proportionately more than the other leaf tissues, producing
a raised puckered surface, with the top of the puckers
progressively going from chlorotic to necrotic tissue
It is fairly present in the form of its oxides giving red or
brown colour to the soil.
well-irrigated areas ferric compounds are
predominantly found and in water logged soils, ferrous
compounds are formed.
Iron also acts as a catalyst and electron carrier in
Iron is a constituent of cytochromes, ferredoxin, catalase,
peroxidase and etc.
It also acts as an activator of nitrate reductase and
These iron-deficient leaves show strong chlorosis at the
base of the leaves with some green netting.
The most common symptom for iron deficiency starts out
as an interveinal chlorosis of the youngest leaves, evolves
into an overall chlorosis, and ends as a totally bleached
The bleached areas often develop necrotic spots
Like iron, the oxide forms of manganese are common in
soil but the more highly oxidised form ( manganese
dioxide) are of very low availability to plants.
It acts as an activator of some oxidases, peroxidises,
dehydrogenases, kinases and decarboxylases etc.
And is essential for the formation of chlorophyll.
It also decreases the solubility of iron by oxidation hence
in certain cases abundance of manganese leads to iron
deficiency in plants.
In leaves light interveinal chlorosis developed under a
limited supply of Mn.
The early stages of the chlorosis induced by
manganese deficiency are somewhat similar to iron
As the stress increases, the leaves take on a gray
metallic sheen and develop dark freckled and necrotic
areas along the veins.
A purplish luster may also develop on the upper
surface of the leaves.
Copper is found in small quantities in soils
Its specific function in plants largely remains to be
determined but its role as a catalyst and regulator is
It is a constituent of ascorbic acid oxidase, laccase,
tryosinase, phenoloxidase, plastocyanin etc.
And is essential for photosynthesis, respiration and
copper-deficient leaves are curled, and their petioles
Copper deficiency may be expressed as a light overall
chlorosis along with the permanent loss of turgor in
the young leaves.
Recently matured leaves show netted, green veining
with areas bleaching to a whitish gray.
Some leaves develop sunken necrotic spots and have a
tendency to bend downward.
Trees under chronic copper deficiency develop a
rosette form of growth.
Leaves are small and chlorotic with spotty necrosis.
Like copper, it is also found in soils in very small quantities
and largely results from concentration and addition from
growing plants and added residue.
little is known about its function like that of iron,
manganese or copper
but it is a component of enzymes like carbonic
anhydrogenase, alcohol dehydrogenase, Lactic acid
phosphatise, carboxypeptidase, etc.
It has been found essential for carbon dioxide evolution
metabolism and synthesis of RNA and auxins.
A close relationship is found between zinc and chlorophyll
Leaves show an advanced case of interveinal necrosis.
In the early stages of zinc deficiency the younger leaves
become yellow and pitting develops in the interveinal
upper surfaces of the mature leaves.
Guttation is also prevalent.
As the deficiency progress these symptoms develop
into an intense interveinal necrosis
It is found widely distributed in small amounts in soils
its higher concentration occurs in mineral oils and
It is an important constituent of the nitrate reducatse
It also acts as an activator of some dehydrogenase
and phosphatase and as cofactors in the synthesis of
It is found necessary to the nodule formation in
legumes for the fixation of atmospheric nitrogen.
leaves show some mottled spotting along with some
In the case of cauliflower, the lamina of the new leaves
fail to develop, resulting in a characteristic whiptail
In many plants there is an upward cupping of the
leaves and mottled spots developing into large
interveinal chlorotic areas under severe deficiency.
At high concentrations, molybdenum has a very
distinctive toxicity symptom in that the leaves turn a
very brilliant orange.
Boron occurs in rocks and marine sediments.
It is absorbed in the form of borate ions.
It is necessary for translocation of sugars
is involved in the reproduction and germination of
It is concerned with water reactions in cells and
regulate the intake of water into the cell.
boron-deficient leaves show a light general chlorosis.
Deficiency symptoms of Chloride
leaves have abnormal shapes, with distinct interveinal
The most common symptoms of chlorine deficiency
are chlorosis and wilting of the young leaves.
The chlorosis occurs on smooth flat depressions in the
interveinal area of the leaf blade.
In more advanced cases there often appears a
characteristic bronzing on the upper side of the
Lincoln Taiz and Eduardo Zeiger, Plant Physiology,