Transcript Cu content in plant

Micronutrient elements
Copper
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The total amount of Cu in the soil is
relatively small. The average Cu content of
the soil is 5-50 μg/g. It is contained in a
number of primary and secondary soil
minerals.
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Minerals
Largest fraction of Cu is usually present in the
crystal lattices of primary and secondary
minerals, such as olivine, hornblende, picrites
biotite, feldspar, chalcopyrite etc.
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Absorbed Cu or occluded Cu
Cu ion is adsorbed to inorganic and
organic negatively charged groups.
Copper is specifically adsorbed to
carbonates, soil organic matter,
phyllosilicate , and hydrous oxides of Fe,
AI and Mn.
The divalent Cu ion has a strong
affinity to soil organic matter compared
with other divalent cations
Cu>Nickel>Pb (lead)＞
(Lead)>Cobalt>Ca>Zn>Mn>Mg
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Copper fractions in soil
Cu in soil solution
The Cu concentration of the soil
solution is usually very low being in the
range of 0.01 to 0.6mmol/m3.
The majority of the Cu in the soil
solution is in the chelated form
(complexed with organic molecules)
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The factors controlling Cu availability in soils
1. Soil pH
The amount of soluble Cu is about 100 times lower
with a pH increase of 1 unit.
2. Soil organic matter
Organic matter complexes (molecular weight <1000)
may increase and decrease the availability of Cu to
plants when molecular >5000.
3. Carbonate or oxides
4. History of arable soil and applications of
agrochemicals such as Bordeaux mixture
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So Cu deficiency often occurs on the Cu
inherently low soils such as sandy podzolic
soils and soils developed on parent materials
poor in Cu; organic soil and peaty soil
calcareous soils high in clay content.
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Cu content in plant
In most plant species, the Cu concentration
in plant is low and in the range of 5 to 20 μg
Cu/g and is normally less than 10 μg Cu/g dry
matter.
Anthers are normally very high in Cu.
Crops species differ in their sensitivity to
Cu deficiency.
The most responsive crops: oats, spinach,
wheat, and lucerne
Medium range: cabbage, cauliflower, sugar
beet and maize
Low response crops: beans , grass,
potatoes and soya beans
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Uptake and transport
The mechanism of Cu uptake is not yet
clear, But Cu2+ must be reduced before it
is transport across the PM
Cu uptake appears to be metabolically
mediated process
High levels of inhibit Zn strong inhibits
Copper uptake and vice versa
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Uptake and transport
Cu is very strongly bound to the root
apoplast.
Copper is not readily mobile in the plant.
when supplied with copper, Cu can move
from leaves to the grains; but in deficient
plants Cu is relatively immobile.
Cu is transported in the form of anionic Cu
complex.
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Function of Cu in plants
1. Important component of many enzymes
Cytochrome c oxidase is one of the most well studied
of Cu containing enzymes in the mitochondrial transport
chain.
The enzymes phenolase (tyrosinase and polyphenol
oxidase
Ascorbic acid oxidase
Amine oxidase which catalyze oxidative deamination.
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2. Necessary for photosynthesis
important in lignin synthesis, is essential
redoxsystem of the photosynthesis e- transport
chain.
3. Involved in the lignification of cell walls
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4. Copper influences both carbohydrate and
nitrogen metabolism
In the vegetative stage Cu deficiency can
induce
lower
concentration
of
soluble
carbohydrate and an accumulation of soluble
carbohydrate in the leaves and roots after
anthesis owing to failure of flower set and
consequent lack of grain filling process.
5. Important for the formation of pollen
sterility of pollen in Cu deficient plant.
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Copper deficiency symptoms
In cereals crops deficiency shows
first in the leaf tips at tillering ．The tips
becomes white and leaves are narrow
and twisted. The growth of internodes is
depressed; excessive tiller occurs; ear
and panicle formation is absent in severe
conditions. Or ear are not fully developed
and may be partially blind in less
deficiency.
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catalyst in photosynthesis and respiration.
constituent of several enzyme systems involved
in building and converting amino acids to
proteins.
carbohydrate and protein metabolism.
It formation of lignin in plant cell walls which
contributes to the structural strength of the
cells, and the plant.
affects the flavor, the storageability, and the
sugar content of fruits.
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High N applications promote plant lodging if Cu is
deficient.
Young tissues show chlorosis, distortion, and
necrosis (death).
The death of the growing points often leads to
excessive tillering in cereal crops and excessive
branching in dicots (non-grass crops).
Some vegetables show a blue-green color before
advancing to chlorosis.
Excessive wilting, lodging and reduced disease
resistance result from the weak cell walls caused
by Cu deficiency.
Reduced seed and fruit yield is caused mainly by
male sterility.
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Copper deficiency often causes a
complete failure to set flowers.
Lettuce and onions most commonly
manifest visible symptoms with only a
slight deficiency occurring.
Copper is found to be evenly distributed
in the plant, but is relatively immobile.
Therefore, a constant supply is needed
throughout the growing season.
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Pigtail whip tail of barley
shows copper deficiency
Left normal wheat. Right wheat with
severe copper deficiency symptoms
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Left normal barley.
Right severe copper deficiency
Heads of wheat grown in copper deficient
soil become bleached and then turn grey;
stems of some cultivars darken
significantly due to melanosis
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For most plants species high concentrations
of available Cu in nutrient medium are toxic
to growth.
Chlorosis is commonly observed symptom of
Cu toxicity, superficially resembling Fe
deficiency.
Inhibit ed root growth is one of the most
rapid responses to toxic Cu levels
Symptoms appear in young tissue ;
 dark green leaves followed by induced Fe chlorosis
 the leaves may appear nearly white;
 thick, short, or barbed-wire looking roots which can
be mistaken for chemical damage
 depressed tillering.
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soils high in iron (Fe), or plants v. efficient in
absorbing Fe can increase the plant concentration at
which Cu has toxic effects, thus lessening the toxic
effect.
Increasing the soil pH should also help reduce toxic
effects, --may cause deficiencies of other nutrients.
leaf analysis may not properly reflect severity Cu
problem because the root damage can become selflimiting to Cu uptake.
orchards field , or cropping history with prolonged
"Bordeaux Mix" use are prone to excess Copper.
Minimizing effects of Cu toxicity
◦ Liming to the proper pH,
◦ using Molybdenum seed treatments,
◦ and increasing the Nitrogen, Zinc and Phosphorus rates
will. Although this is not well proven, foliar Fe might help
offset the damaging effects of excess Cu.
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Conditions that may have copper deficiencies
1. Cu deficiency is most common in soils with
very high levels of organic matter or sandy
soils with a high pH.
2. High levels of Fe, Zn, and P can also cause Cu
deficiency
3. Small grains, carrots, and onions are sensitive
to low levels of Cu
4. N Stress: low N availability reduces plant vigor
hindering nutrient uptake incl. copper
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Root Growth: Cu the most immobile micronutrient,
therefore inhibited root growth inhibits Cu uptake.
Soil pH: Acid soils increase Cu uptake and High pH
inhibits uptake.
Organic Matter: readily and tightly complexed by OM,
therefore high SOM levels reduce Cu availability.
Flooding: Waterlogging reduces Cu availability, Cu will
become available again if soils are drained
Cu:Zn Balance: High Zn levels will reduce Cu availability.
Cu:N Balance: High N uptake in the presence of marginal
Cu levels can lead to a reduction of Cu transport into the
growing tips of plants.
Cu:P Balance: High soil and plant P reduces Cu uptake
due to reduced mycorrhizal uptake by plant roots.
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Copper sulfate (CuSO4·5H20) –
25% Cu is the most common fertilizer
Cu Oxides 75% -89% Cu, insoluble in
water
Chelated Cu: EDTA, Cu amino acids
and Cu fulvic complex
Manure and other organic sources can
supply chelates as well as Cu
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Application
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Soil application
Cu can be applied to the soil with
rate of 1-10 kg Cu/ha, more for organic
soil
If added to the soil, Cu should
generally be broadcast and incorporated.
There is some concern that putting Cu in
bands could cause root damage.
Foliar applications
CuSO4, CuO or Cu chelates
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Total Mn content in the soil
The average Mn content in the soil is20
~3000 μg Mg/g.
It is found in primary minerals (pyrolusite or
MnO2,manganite or MnO(OH),clays, oxides,
and hydroxides.
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Mn fractions in soil
Crystalline Mn oxides: MnO2, MnO·nH2O
Easily reduced Mn (amorphous): Mn2O3,
MnO(OH) etc
Exchangeable Mn: bounded to the organic or
clay
Soluble Mn: Mn2+
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Aerobic and OH-
Mn2+
Mn2O3
Anaerobic
and H+
Aerobic
and OH-
Aerobic
and OH-
MnO2·nH2O
dehydrate
MnO2
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Redox conditions
as Eh increase, the Mn availability decrease
pH
pH>5 to 6, the reduction rate decreases by a factor
10 to 100
Forms of Mn oxide
amorphous > crystalline
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Organic matter
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Microbial activity pH dependent (pH=7)
large organic matter reserves are
particularly prone to Mn deficiency
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Treatment
g CaCO3/pot
0
Flooding
g, dry matter/pot
Mn concentration
Μg/dry matter
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3.1
426
0
20
+
-
1.2
5.7
6067
99
20
+
3.0
954
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Mn uptake and translocation
Mn uptake occurs in the form of Mn2+ by
facilitated diffusion presumably.
Mg2 + and Ca2 + depress Mn2+ uptake
Mn 2+ depresses Fe uptake
Mn is relatively immobile in the plant and is
scarsely translocated in the phloem.
Mn is preferentially translocated to
meristem.
Si enhances the distribution of Mn in
barley plants
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Function of Mn in plants
1. Activates a number of enzymes
Mn bridge ATP with the enzyme complex,
such as phosphokinase and
phosphotransferases)
It activates PEP carboxylase.
It depress the peroxidase and IAA oxidase
activity
2. Mn containing enzymes
MnSOD detoxifies the superoxide radical in
the mitochondria of eukaryote
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3. Photosynthesis
Involved in the splitting of H2O and O2 evolution in
photosynthesis
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4. Other reactions associated with the
photosynthetic e- transport are affected by
the Mn deficiency.
Photophosphorylation
Reduction of CO2
Reduction of nitrite
Reduction of sulphate etc
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Deficiency symptoms
Chloroplasts are the most sensitive of all
organelles to the Mn deficiency and
disorganization of lamellar system occurs.
So interveinal chlorosis of young leaves. It is
resembles Mg deficiency (older leaves).
In monocots and particularly in oats, Mn
deficiency symptoms appear at the basal part
of leaves as greenish grey spots and strips
during tillering stage.-- “grey speck”
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Wheat, Oats, Barley
Manganese deficiency
Field comparison of susceptibility.
Oats (center) more susceptible than barley (left) and wheat (right).
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Irregular, grayish-brown
lesions, which coalesce
and bring about collapse
of leaf (gray speck
symptoms (left).
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Oat Leaves and Heads Manganese deficiency (right): Leaves, grayishbrown elongated specks and streaks, most prevalent in basal halves;
breaking of leaves with distal areas remaining green empty panicles.
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Rye and wheat Mn deficiency：interveinal chlirotic
spot and stripe on the middle and basal halves
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Manganese deficiency in oranges
In dicots, the symptoms are
often characterized
by small yellow spots on the leaves
and interveinal chlorosis.
It differs from that of Fe deficiency
where the whole young leaf
becomes chlorotic.
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Apple, Variety, Early Victoria. Leaves
severe chlorosis over most of tree;
young leaves of terminal shoots not as
severely affected as older leaves.
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Apple Foliage Manganese deficiency
Leaves intervenal chlorosis progressing
from margins towards midrib.
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Dwarf Bean Plants Manganese deficiency :Leaves severe chlorosis and
necrosis；Haricot Bean Plants Manganese deficiency Leaves strong chlorotic
motting
Pea Seeds Manganese deficiency :Brown lesions in centers of cotyledons
("Marsh Spot") (left of bottom)
Runner Bean Seeds Manganese deficiency brown lesions in cotyledons.
(right of bottom)
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The critical deficiency level for most plant
species is in the range of 10 to 20μg Mn/g dry
matter.
200μg Mn/g dry matter for maize and 5300μg
Mn/g dry matter for sunflower are toxic.
The toxicity symptoms are generally
characterized by brown spots of MnO2 in older
leaves surrounded by chlorotic areas.
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Mn toxicity in spring barley was
characterized by dark brown spots at the
leaf tips which were enrolled and had
extremely high Mn concentrations.
Another symptom of Mn toxic is the loss of
dominance and the proliferation of
auxiliary shoot.
Some times Mn excess can induce a
deficiency of other mineral nutrients such
as Fe, Mg and Ca.
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Conditions that may have Mn deficiencies
1. High pH soils
2. High organic matter soils
3. High levels of Cu, Fe or Zn
4. Dry weather
5. Soils
organic soils, some podzolic soils and sandy soils etc
6. Crops
oats and peas are the most sensitive to Mn
deficiency; other sensitive crops are: apple, cherry,
citrus, raspberry, and sugar beet
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Kinds of manganese fertilizer
1．Manganese sulfate (MnSO4·4H20)
Mn 26-28%
MnSO4·4H20 is the most common source of
Mn.
It can be added to the soil or applied
to the foliage. Banding is more effective
than broadcasting.
2. Manganese chloride MnCl2 17 %
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Kinds of manganese fertilizer
3． Chelated Mn
Mn EDTA Mn 12%
Used for foliar applications. Applying
chelated Mn to the soil is ineffective,
because Fe or Ca will replace the Mn
in the chelate.
4．Manure supplies Mn and organic matter
for the formation of chelates
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