Micronutrient elements
Chapter 14
General Characteristics
Nutrient Soil Content (kg/ha) Corn Removal (kg/ha)
Boron (B) 22-225 0.07
Copper (Cu) 2-450 0.06
Iron (Fe)
11,200 – 224,000 0.12
Manganese (Mn) 112-11,200 0.09
Molybdenum (Mo) 1-8 0.03
Zinc (Zn) 22-675 0.17
Micronutrients in Soils and Crops
? A,Micronutrients are required by all
plants but in smaller amounts
compared to the macronutrients,
? Deficiencies of micronutrients can
reduce growth just as much as
deficiencies of macronutrients,
Remember the ―Law of the Minimum‖.
General Characteristics
B The amount of micronutrient that is
needed by the plant can have a narrow
range,If the amount of micronutrient is
too high,it is possible for toxicity to
occur.
Available forms
1,Cations,Fe2+,Fe3+,Mn2+,Zn2+,Cu2+
2,Anions,MoO42-,Cl-
3,Neutral,H3BO3
General Characteristics
Micronutrient function in plants
1,Enzymes and coenzymes
a) Structural component of enzymes
b) Involved in the activation and regulation
of enzymes
2,Oxidation and reduction reactions
Micronutrients are involved in electron
transport
Micronutrient transformations in the soil
1,The transformations that micronutrients undergo in
the soil vary depending on the nutrient,but overall,
the reactions are similar to what has already been
discussed for macronutrients.
a) Mineralization and immobilization
b) Adsorption and desorption to clay or organic
matter surfaces
c) Precipitation and dissolution of secondary
minerals
Micronutrient transformations in the soil
2,Micronutrients undergo one
transformation that is quite different
from the transformations that we
discussed for the macronutrients,That
transformation is called chelation,
a) The word chelate means ―claw‖,Chelation
refers to the process in which organic molecules
in the soil form a complex with micronutrient ions,
b) The chelated micronutrients are carried by
mass flow and diffusion to the root surface.
The chelation process in the soil
c) The chelate is broken down in rhizosphere,
The micronutrient is taken up by the root and
the organic molecule diffuses away,
d) The organic molecule can complex with
more micronutrients and the process is
repeated,
The chelation process in the soil
e) There is still a lot about the chelation of micronutrients that
is unknown,The organic molecule that forms the chelate
may be derived from:
Natural chelates
(1) Organic compounds released by the roots or soil
microorganism,such as Siderophores高铁载体 and
phytosiderophores植物高铁载体
(2) Compounds released during the decomposition of soil
organic matter,such as fulvic acids
(3) Man-made chelates,EDTA,DTPA EDDHA etc
The chelation process in the soil
Soluble chelates increase the
availability of micronutrient cations,Fe,
Zn,Mn,and Cu,The chelates help
protect the ions from precipitation or
adsorption reactions,
The chelation process in the soil
a) Solubility of the micronutrient (affected by
factors such as pH)
b) Percent of exchange sites that are
occupied by the micronutrient
c) Soil organic matter
(1) Affects the balance between adsorption and
desorption
(2) Organic matter is also involved in the
chelation process
Factors that affect micronutrient availability
Iron
? Fe in the soil
Fe is one of the most abundant elements
in the surface of the earth,It makes up about
5% weight of the earth’s crust and is
invariably present in all soils.
Iron forms in soil
? Mineral bearing iron
? Primary mineral:
? olivine,augite(辉石 ),hornblende and biotite(黑云母 ).
? Minerals Fe oxides
? Geothite (α-FeOOH针铁矿 ),haematite（赤铁矿 ) and
ferrihydrate（ HFe5O8·4H2O水化铁） etc
Iron in the soil solution
1,Soil solution concentrations are very low,
The concentration of Fe3+ in the soil is
~10-15 to 10-20 M,
? Soluble inorganic forms include Fe3+,Fe(OH)2+,
Fe(OH)2+ and Fe2+
? Iron solubility is largely controlled by the
pH and Eh.
? Fe3+ +3OH-= Fe(OH)3
? At higher pH levels Fe3+ activity in solution decrease
1000 fold for each pH unit rise
In aerobic soils,Fe2+ is oxide to Fe3+,
and formation of Fe(OH)3 precipitation.
In water-saturated soils (anaerobic),
Fe3+ is converted into Fe2+,which
increase Fe solubility.
Fe(OH)3 +e-+3H+ Fe2+ +3H2O
Iron in the soil solution
Siderophores and phytosiderophores
Siderophores are a kinds of
organic substance (such as
nicotinamine (烟酰胺 ),mugineic acid麦
根酸 and avenic acid etc) produced by
the bacteria,fungi and plant),which can
form organic complexes or chelates with
Fe3+,and increase the movement of
iron in soil.
Characteristics of siderophores
they are molecules with a high
affinity for Fe3+,and removes the Fe from
minerals and contributes their dissolution.
these Fe-chelates are highly soluble
and are stable over a wide pH range.
they are of crucial importance for the
Fe transport in soils and the Fe supply of
plants.
Plant uptake of Fe
1,Plants can take up both Fe2+ and Fe3+,
In general,Fe2+ pass through a species
channel of PM,Fe3+ is reduced to Fe2+
before absorption occurs,Fe3+ uptake is
important for grasses
Phytosiderophores molecular is take up
by specific transporters located in PM of
graminaceous禾本科 monocots root,and Fe
is reduced in cells.
Factors that affect Fe uptake
1,Plants have different abilities to take up Fe
from the soil solution
Not only different species (wheat vs,bean) but even
different genotypes.
2,pH
Fe3+ reduction requires a pH of about 5 at the
apoplastic site of the reductase,
The Fe uptake of general plant is affected by the pH,but
Fe uptake of graminaceous monocots is little affected by pH.
3,Ability of Fe3+ reduction in the root
Effect of pH in the nutrients solution and N sources on the
Fe concentrations in leaves and roots and chlorophyll
concentration in the youngest leaves of helimanthus
annuus (Kosegarten et al 1998)
T r e a t me n t C h l o ro p h y l l,m g / g f r,w t, L e a f,μ g F e / g d ry w t, R oot,μ g F e / g d ry w t,
NH 4 N O 3,p H 4,c o n t r o l 1, 5 0 7 0, 8 156
NH 4 N O 3,p H 6, 5 0, 9 5 *** 3 2, 5 * * 307 *
N O 3
-
,p H 6, 0 0, 2 8 * * * 2 9, 1 * * 351 **
*,* *,* * * r e p r e s e n t s i g n i f i c a n t l y f r o m t h e c o n t r o l a t p < 0, 0 5,0, 0 1 a n d 0, 0 0 1,r e s p e c t i v e l y
Translocation of iron
? The Fe2+ in the cytosol is presumably
oxidized in transport into the xylem.
? Long- distance transport in the xylem is
Fe3+ complex when an excess of citrate in
the xylem.
? In the phloem and in the symplasm Fe is
transported as an nicotianamin,
Fe concentration in the plant
Fe concentrations in dry plant tissue
are commonly around 50-100 μg/g
(compared to N which is typically 10,000-
50,000 μg/g
Most of Fe is in the vegetative parts,
grains and tubes are often considerably low.
The content of iron in the plant is
effected by the soil iron availability,
1,Fe is important in the process of chlorophyll and
haem formation in plants
text book p392
2,Fe is required for electron transport in
photosynthesis,
It is an important part of several molecules
that are involved in photosynthesis,
Iron sulphur proteins or ferredoxin and ferritin(铁
蛋白 )
Roles of iron in plant
Roles of iron in the plant
3,Chelate complex Fe is an important electron
acceptor in redox reactions
Haem is prosthetic groups辅基 of several enzymes
(catalase,peroxides,cytochrome oxidase etc.),
4,Nitrogenase comprises an Fe protein and FeMo
protein;
5,Ribonucleotide reductase,It is required of
synthesis of DNA and RNA,which is required for
the synthesis of proteins.
Fe deficiency symptoms
1,Interveinal yellowing and chlorosis of whole leaves and
emerging leaves.
Symptoms appear on youngest upper leaves The leaves are
yellow,with the veins remaining green,
2,Whole leaves become chlorotic and pale and reduction of
leave.
3,Not all species are equally susceptible to Fe deficiency
Calcifuge species(避钙植物） is susceptible to Fe
chlorosis;
The most important commercial crops affected are
citrus,deciduous fruit trees落叶果树 and vine;
Field beans,soybeans,legumes,and tomato etc,
Iron deficiency in soybeans
Iron deficiency in rice
Wheat Plants Iron deficiency
Severe chlorosis of leaves,
most severe on younger growths;
die-back of chlorotic leaves
Oat Plants Iron deficiency
Young leaves severe chlorosis;
chlorosis begins as interveinal stripes,
越橘
Fe deficiency of grape leaves (up)
Fe deficiency of pear (left and middle of bottom),and apple tree (right of bottom)
Tip leaves chlorotic; small veins show as fine network in early stages; margins
develop brown patches
Potato Foliage
Iron deficiency
Young leaver strongly chlorotic;
veins may remain green;
margins and tips brown patches,
Potato Foliage
Iron deficiency
Young leaver strongly chlorotic;
veins may remain green;
margins and tips brown patches,
TOMATO FOLIAGE
Iron deficiency
Tip leaves,especially basal
areas of leaflets,
intense chlorotic mottling; stem
near tip also yellow,
Cabbage Plant (Savoy皱叶
甘兰 )
Iron deficiency
Severe chlorosis of leaves
beginning as a chlorotic
mottling色斑,
? 水稻铁中
毒：青铜
色叶片
bronzing
leave or
bronzed
disease
Lime induced chlorosis
? Iron chlorosis may result from an absolute
Fe deficiency in soil,such as organic soils
and degraded sandy soils,But such cases
are rare.
? However,iron chlorosis occurs frequently
on the calcareous or saline and sodic soils,
The chlorosis is not caused by absolute
Fe deficiency,The Fe concentration in the
chlorotic leaves can be higher than in the
green leaves,Why?
Lime induced chlorosis
? Calcareous soils,high pH and high HCO3-
concentrations in soil solution may depress or
even block F3+ reduction in the root apoplast,
? The nitrate nutrition is predominately in
Calcareous soils,which induce high apoplastic
leaf pH,so Fe3+ reduction in the leaf apoplast is
restricted and hence the uptake of Fe from the
apolast into the cytosol impaired.
? Spraying chlorotic leaves with dilute acids results
in regreening,So does fusicoccin ( 壳梭孢素 )as
well as IAA
Effect of spraying Fe-EDDHA or dilute H2SO4 for
curing Fe chlorosis on chlorophyll concentration and
pod yield of Pisum sativum (Shau 1987)T r e a t me n t C h l o r o p h y l l,mg / g / f r e s h w e i g h t P od y i e l d M g / h a
C o n t r o l,n o s p r a y i n g 1, 3 7 1, 7 9
H 2 SO 4 1, 8 3 3, 3 6
Fe - E D D H 1, 7 8 3, 1 5
P <0,0 5 0, 6 7 6 0, 6 7 6
Common Fe Fertilizers
1,Ferrous sulfate,FeSO4·7H2O,(20% Fe)
a) applied to foliage as a solution
b) injected into the tree trunk
2,Iron oxalate,Fe2(C2O4)3,(30% Fe)
3,Iron citrate,FeC6H5O7·X H2O,(16%-
18% Fe)
Common Fe Fertilizers
3,Chelated iron
Chelated iron compounds consist of an
organic molecule that binds iron and makes it
solubility in soil solution and more available to
plants,
FeEDDHA,Fe 6%
FeDTPA,Fe10%
FeEDTA,Fe 9-12%
HEDTA,Fe 5-9%
b) Chelated compounds must be placed into
the root zone to be most effective,Or foliage
application.
Applications should be made in the
spring to coincide with the beginning of
growth.
In most cases,it is necessary to treat the
soil every year.
Common Fe Fertilizers
Management strategies
? A,Soil application can be helpful when the pH is
low,but not at high pH,
? B,Alternative methods of Fe-fertilization include:
1,Foliar application
2,Seed coating
3,Injecting Fe into the tree trunk
Other management strategies
1,Lower the pH of the soil (increases
soluble Fe
2,Combined the organic matter content
and FeSO4 together.
3,Choose varieties that are not so
sensitive to iron deficiencies.
Zinc
Soil Zinc
The total amount of Zn in the soil is
relatively small,The average Zn content
of the soil is 17 to160μg Zn/g soil.
The level of Zn in soils is very much
related to the parent materials.
Basic igneous rocks > siliceous parent
materials
sometimes,pollution soil have high Zn
levels
zinc content in soil
Soil Zinc
primary and secondary soil minerals:
augite (辉石 ）, hornblende,and biotite (黑云母 ）
salts,
ZnS,Sphalerite (ZnFe)S 闪锌矿, smithsonite
(ZnCO3)菱锌矿 willemite (Zn2SiO4)硅锌矿
Zinc fraction in soil
Soil Zinc
Soil solution Zn
1,the Zn concentration is very low and in
the 3╳ 10-5 to 5 ╳ 10-3mol/l.
2,forms of Zn in soil solution
Zn2+,ZnOH+ or ZnCI+
Most of the Zn in the soil solution is
usually in the chelated form
Soil Zinc
Exchange Zn
Clay minerals and organic matter have
exchange site of Zn ions.
Specific adsorption of Zn2+ by carbonate:
Magnesite (菱镁矿） >dolomite（白云石） >calcite（方解石）
Adsorption and occlusion of Zn by carbonate
are major cause of poor Zn availability and the
appearance of Zn deficiency on calcareous soils.
Soil Zinc
? Organic Zn
? Zn can interact with organic matter in soil
? Soluble Zn organic complexes is about
60% of total Zn in soil solution.
? Amino acids,organic acids and fulvic
acids富哩酸 complexes with Zn are
soluble; but insoluble organic complexes
are derive from humic acid胡敏酸,
Soil Zinc
? pH:
Soluble Zn+2 is ~100 times lower with a pH
increase of 1 unit
organic matter
Zn complexes can either increase or decrease
the availability of Zn to the plant.
carbonate content
History of arable soil
Excess application P fertilizers or iron Mn
etc
Factors affecting soil Zn availability
Zinc in plants
? Zn Content in plant
? For most plant species Zn
concentrations in leaves below 10-15 μg
Zn/g dry matter are indicated of Zn
deficiency and concentration in the range
of 20 to 100 μg Zn/g dry matter are
sufficiency,
Zinc in plants
Uptake and translocation
The uptake may be as facilitated
diffusion through membrane channels
or mediated by specific transporters.
The uptake is strongly inhibited by
the Cu,the Fe,Mn and alkaline earths
cations碱土金属离子 etc.
And is reduced by low temperature.
Zinc in plants
? Translocation
? Zn is not bound to stable ligand.
? It is translocated as zinc citrate
complexes
? Zn is phloem-mobile,but its
translocation is varies among different
plants,
? In the high Zn level,excess Zn is
deposited to a large extent in the older
leaves
Zinc in plants
Function of Zn in plants
1,Activates 300 enzymes
Carbonic anhydrase( 碳 酸 酐 酶 ） is
particularly important for C4-species.
Alcohol dehydrogenase is important in
root under anaerobic conditions.
Cu-Zn superoxide dismutase (SOD) is
required for the detoxification of the
superoxide radical超氧自由基, It is important
to resist the sunscald (日灼病 ）
Enzymes involved in the carbohydrate
metabolism.
Zinc in plants
Function of Zn in plants
2,Necessary for the plant hormone (for
example IAA)
In Zn deficient plant it is low rates of
stem elongation,low auxin activities and
low trytophan (色氨酸 ）
3,Zinc is very closely in the N metabolism of
plant.
RNA polymerase contains Zn
Zinc deficiency affected the structural
integrity of the cytoplasmic ribosomes.
Deficiency symptoms
1,Stunted (reduced) growth
Unevenly distributed clusters or rosettes
of small stiff leaves (Small,narrow,thick
leaves) are formed at the ends of the
young shoots,Frequently the shoots die off
and leaves fall prematurely.
Apple tree,rosette and little leaf.小叶病
与簇叶病,
Fewer bud,bark is rough and brittle
Deficiency symptoms
2,Chlorosis in the interveinal areas of the
leaf
In the monocots chlorotic bands form on
either side of midrib of the leaf which later
become necrotic,The symptoms appears on
young leaves.
In most case,the deficiency symptoms of
vegetable crops is characterized by short
internodes and chlorotic areas in older leaves.
Sometimes chlorosis also appears in younger
leaves.
Zinc deficiency in corn
Zinc deficiency in canola (chlorotic
mottling and than necrosis)
Zinc deficiency of citrus
spring
summer
Zinc deficiency of rice
?
? Center,healthy shoot from
zinc deficient apple tree;
? Left and Right,shoots
showing zinc deficiency
symptoms; buds along
shoots fail to develop,
leaves small and narrow
("Little Leaf" condition)
and tend to form rosettes
at tips of shoots,
Zinc toxicity and tolerance
? Excess Zn supply results in reduction of
root and leaf expansion which is followed
by chlorosis,Red-brown pigment was
formed under conditions of excess Zn in
soya beans,
? Some plants species are Zn tolerant,They
can accumulated 600 to 7800 μg Zn/g dry
matter,
?
? Sugar Beet Plants
Zinc toxicity
? Growth severely
stunted; young leaves
show chlorotic iron
deficiency symptoms
followed by severe
intervenal necrosis
? Excessive Zn of
cucumber,dark
green of older
leave (left).
? Younger leave
shows slight
green with
interveinal
brown spot like
pinhole
Conditions that may have Zn deficiencies
A,Soils with a high pH (low Zn solubility)
B,Fine-textured soils (Zn adsorption)
C,Cool,wet conditions
D,High levels of Cu,Fe,Mn or P can
cause a Zn deficiency
E,Some crops are more sensitive than
others
1,Corn and beans are sensitive
2,Sensitive crops following sugar beets
may have a Zn deficiency.
Conditions that may have Zn deficiencies
Zinc fertilizer
A,Kinds of Zn fertilizer
1,Manure supplies Zn and organic molecules
for chelation
2,ZnSO4 (35% Zn) is most common fertilizer
3,Chelated zinc
Application of Zn fertilizer
1,Zn may be applied to the soil or to the
foliage
2,Banding is usually more efficient than
broadcasting – but don’t band P and
Zn together.
Zinc fertilizer
Copper
Copper in the soil
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.
Copper fractions in soil
? Minerals
? Largest fraction of Cu is usually present in the crystal
lattices of primary and secondary minerals,such as
olivine,hornblende,picrites辉石,biotite,feldspar,
chalcopyrite黄铜矿 etc.
?
Copper fractions in soil
? 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 (层状硅酸盐 ),
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
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)
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 (波
尔多液 ）,
The factors controlling Cu availability in soils
So Cu deficiency often occurs on the
Cu inherently low soils such as sandy
podzolic soils灰化土 and soils developed
on parent materials poor in Cu; organic
soil and peaty soil calcareous soils high in
clay content.
Reclamation disease 开垦病
Copper in plants
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 (花 ） are normally very high in Cu.
Crops species differ in their sensitivity to Cu
deficiency.
The most responsive crops,oats,spinach,wheat,
and lucerne (紫花苜蓿 )
Medium range,cabbage,cauliflower,sugar beet
and maize
Low response crops,beans,grass,potatoes and
soya beans
Copper in plants
? Uptake and transport
? The mechanism of Cu uptake is not yet
clear,But Cu2+ must be reduced
before is transport across the PM
? Cu uptake appears to be metabolically
mediated process
? Zn strong inhibit the Copper uptake and
vice versa
Copper in plants
? 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
deficiency plants Cu is relatively immobile.
? Cu is transported in the form of anionic
Cu complex.
Function of Cu in plants
1,Important component of many enzymes
The most common of the three types of superoxide
dismutase iosenzymes contains Cu and Zn (Cu-ZnSOD)
Cytochrome c oxidase is one of the most well studied
of Cu containing enzymes in the mitochondrial transport
chain.
The enzymes phenolase (tyrosinase酪氨酸氧化酶
and polyphenol oxidase多酚氧化酶 )
Ascorbic acid oxidase
Amine oxidase which catalyze oxidative deamination.
Function of Cu in plants
2,Necessary for photosynthesis
Blue protein or plastocyanin 质体蓝素
(2Cu/molecular) is essential redoxsystem of the
photosynthesis e- transport chain.
3,Involved in the lignification of cell walls
Phenolase ( 酚酶 ) and laccase ( 漆酶 ) are
involved in lignin synthesis.
Function of Cu in plants
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 (开花期 ） 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.
Copper deficiency symptoms
In cereals crops deficiency shows
first in the leaf tips at tillering (分蘖
期 ),The tips becomes white and leaves
are narrow and twisted,The growth of
internodes is depressed; excessive
tiller occurs; ear（ 小穗 ） and panicle(圆
锥花序 ） formation is absent in severe
conditions,Or ear are not fully developed
and may be partially blind in less
deficiency.
Copper deficiency symptoms
? In Cu deficient trees the development of
― pendula‖(摇摆） forms may occurs.
? In N application soil plant is easily to
lodging if Cu deficient.
Copper deficiency in barley
Pigtail whip tail of barley
shows copper deficiency
Left normal wheat,Right wheat with
severe copper deficiency symptoms
upright empty headed Park wheat at right is grown on
0.6 ppm DTPA Cu soil,
At left,same crop grown on soil amended with 12 lb
Cu per ac as CuSO4,
Yields were 19 bu per ac vs 51 bu per acre
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黑变病,
Toxic of Cu
? 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 of root
growth is one of most rapid response to
toxic Cu levels
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
Copper fertilizer
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
T a b l e 7, P a r k w h e a t r e s p o n s e t o c o p p e r f e r t i l i z a t i o n n e a r T o f i e l d,A l b e r t a,*
M e t h od of
c op p e r ap p l i c at i on
Y i e l d b u / ac r e
3 yr, A vg,
C on t r ol 44
C op pe r c he l a t e s oi l s pr a y 59
C op pe r s ul ph a t e s e e d - r o w 56
C op pe r s ul ph a t e ba nd 50
C op pe r s ul ph a t e br oa dc a s t 60
*O ne - t i m e a pp l i c a t i on of C u c he l a t e ( 1 l b,C u/ a c r e a s C u - E D T A ) a nd C u s ul ph a t e ( 3 l b,C u/ a c r e a s
C u s ul ph a t e ),
Cu concentrations of organic manures and
wastes (Dam Kofoed 1980)
F r e s h w e i gh t,μ g g
- 1
D r y w e i gh t,μ g g
- 1
C a t t l e m a nu r e 9 34
P i g m a nu r e 21 86
P ou l t r y m a nu r e 30 69
S l ur r y,pi g 18 265
S l ur r y,c a t t l e 4 43
S l ud ge ho us e ho l d 46 1 13
S l ud ge,i nd us t r y 353 1477
? 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
Application
Manganese
Manganese in the soil
? 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 软锰矿,manganite or MnO(OH)水
锰矿 ),clays,oxides,and hydroxides.
Manganese in the soil
? 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+
Oxdation/reduction processes of Manganese in the soil
Mn2+ Mn2O3
MnO2·nH2O
MnO2
Aerobic and OH-
Aerobic
and OH-
dehydrate
Aerobic
and OH-
Anaerobic
and H+
Factors of control of Mn availability in soil
? Redox conditions
? as Eh increase,the Mn availability decrease
? pH
? pH>5 to 6,the reduction rate decrease by a factor 10 to
100
? Forms of Mn oxide
? amorphous > crystalline
? Organic matter large organic matter reserves are
particularly prone to Mn deficiency
? Microbial activity pH dependent (pH=7)
Effect of liming and a three day period of flooding
on dry matter yield and Mn concentrations in
lucerne (Graven et al,1965)
T r e a t m e n t
g C a C O 3 / p o t
F l o o d i n g g,d r y m a t t e r / p o t
M n c o n c e n t r a t i o n
Μ g / d r y m a t t e r
0 - 3, 1 4 2 6
0 + 1, 2 6 0 6 7
2 0 - 5, 7 9 9
2 0 + 3, 0 9 5 4
Manganese in plants
? Mn uptake and translocation
? Mn uptake occurs in the forms of Mn2+ by facilitated
diffusion presumably.
? Mg2 + and Ca2 + depress Mn2+ uptake
? Mn 2+ depress the Fe uptake
? Mn is relatively immobile in the plant and
is scarsely translocated in the phloem.
? Mn is preferentially translocated to meristem.
? Si enhanced the distribution of Mn in barley
plants
Manganese in plants
? 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 (真核细胞）
Manganese in plants
3,Photosynthesis
Involved in the splitting of H2O and O2 evolution in
photosynthesis – Hill reaction
Manganese in plants
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
Deficiency symptoms
Chloroplasts are the most sensitive of all
organelles to the Mn deficiency and
disorganization of lamellar( 片层 ） 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‖ 灰斑病
Wheat,Oats,Barley
Manganese deficiency
Field comparison of susceptibility,
Oats (center) more susceptible than barley (left) and wheat (right).
Oat Leaves and Heads Manganese deficiency (right),Leaves,grayish-
brown elongated specks and streaks,most prevalent in basal halves;
breaking of leaves with distal areas remaining green empty panicles.
?
Irregular,grayish-brown
lesions,which coalesce
and bring about collapse
of leaf (gray speck
symptoms灰斑病 ) (left),
Rye and wheat Mn deficiency,interveinal chlirotic
spot and stripe on the middle and basal halves
? ?
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.
Apple,Variety,Early Victoria,Leaves
severe chlorosis over most of tree;
young leaves of terminal shoots not as
severely affected as older leaves.
Apple Foliage Manganese deficiency
Leaves intervenal chlorosis progressing
from margins towards midrib.
?
?
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)
? ?
?
Manganese toxic
? 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
toxicity,
? The toxicity symptoms are generally
characterized by brown spots of MnO2 in
older leaves surrounded by chlorotic areas.
Mn toxicity of orange and lemon
Mn toxicity of vegetable rice
Manganese toxic
? 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（分枝，分蘖增加）,
? Some times Mn excess can induce a
deficiency of other mineral nutrients
such as Fe,Mg and Ca.
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(灰化土 ) and sandy soils
etc
6,Crops
oats and peas are the most sensitive to Mn
deficiency; other sensitive crops are,apple,cherry,
citrus,raspberry(悬钩子 ),and sugar beet
Manganese Fertilizer
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 %
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
Kinds of manganese fertilizer
Boron
Soil boron
Total boron in the soil
The content of B in the soil ranges
between 20-200 mg/kg dry weight,Most
of which is inaccessible to plants.
Boron in the soil solution
1,Between pH 5 and 9,H3BO3 is the
dominant form of B in the soil solution.
2,The pH of the soil solution and the
amount of clay,oxides,and organic
matter are important factors that affect
B availability.
Soil boron fraction
? B containing Minerals
? Tourmaline (30-40 mg B/kg) and hydrated
minerals
? Absorbed B
? AI and Fe oxides,clay minerals,calcium
carbonate,and organic matter
? Ligand exchange,
kaolinite>montmorillonite>illite
Soil boron fraction
? Organic matter bounding B
? the sorption capacity for B in composed
organic matter is about 4 times greater than
for soil or clay,It is believed to be ligand
exchange.
? Hot water soluble B (0.5-2.0 mg B/L)
? Soluble B consists mainly of boric acid
which under most soil pH conditions (pH 4-8)
? B(OH)3 + H2O B(OH)4-; pK4=9.2
Soil boron fraction
Factors affecting boron availability
1,pH
Absorption of B is closely dependent on soil
pH,adsorption increase the pH range 5-9
2,B leaching
In acid,sandy soil or podzolic soil,B is easily
leached from soil; but in arid and semiarid regions,
B may accumulate to toxic concentration.
3,Organic matter
Native B and hot water soluble B in soil are
significantly correlated with organic C content.
Effect of soil pH and carbonate on the proportion of
sugar beet infected by crown and heart rot
(scheffer and Welte 1955)
P e r c e n t a g e o f s u g a r b e e t
pH C a r b o n a t e,%
H e a l t h y I n f e c t e d d e a d
6, 7 0, 1 100 0 0
7, 0 0, 1 99 1, 0 0
7, 5 0, 3 46 40 14
8, 1 1 4, 4 0 25 75
B deficient Soils
? Soils developed from sandstones and acid
igneous rocks
? Spodosol灰土 and podzols 灰壤
? Sometimes Andosols,Lithosols 石质土 and
Luvisols 淋溶土
? Sandy soil
? Liming acids with marginal B
concentrations
? Hot water soluble B <0.5 mg/L
Boron in plant
Uptake
B uptake is a possible combination of
active transport as esters with cis diols (顺式 二
醇 ) and passive diffusion as undissociated boric
acid,
But the exact nature of boric acid
transport across cell membrane is still not
totally resolved.
B in plant
Translocation
To most of plant species,B is translocated
through the xylems,and limited phloem,It is
controlled by the transpiration flow.
B is not readily transported in the plant,
Deficiencies occur first in the growing points and
young leaves.
But in some species,such as celery,carrot,
bean,and cauliflowers,apple,pear,and apricot杏,
B is mobile and is transported as a complex with
polyols (多元醇）,
Function of B in the plant
? Cell walls
? B is now believed to play a key role in
the structure and integrity of cell walls,
The chemical composition and
ultrastructure of cell walls are quickly
affected by a lack of B.
? The role of B in cell walls is cross
linking of pectic polymers (B-RG）,
? It is important to cell wall structure.
Function of B in the plant
? Membrane function
? 1.The effects of B are thus mediated either directly
or indirectly by the plasmamembrane bound H+
pumping ATPase.
? 2.The effects of B are primarily on
plasmmembrane itself (Cakmak and R?mheld
1997),
? B stabilizes the structure of plasma membrane by
complexing membrane compounds containing cis-diol
groups such as glycoproteins and glycolipids to keep
channels and enzymes at optimum conforation within the
membrane,
? 3.B exerts its most important influence at the
cell/plasma interphase.
Function of B in the plant
Other functions
Pollination
B was associated with the higher growth
rate of pollen tubes.
Root elongation
IAA levels is regulated by the B via IAA
oxidase activity
? Meristematic activity
? synthesis of N-bases such as uracil
Deficiency symptoms
1,Abnormal or retarded growth of apical
growing points,in advantage stage,death
of the terminal growing points
2,Stems have an unusual shape,They may
become thick and crack.
3,Youngest leaves are misshapen,wrinkled
and are often thicker and of a darkish blue-
green color,Irregular chlorosis between
the intercostal veins肋间脉 occur.
4,The roots may grow in a very unusual way.
In turnips芜青 and swedes甘蓝,B deficiency result in
glassy like root which are hollow and cracked
5,Flower and fruit formation is restricted or inhibited.
The tissue of the fruit may have some soft,brown spots,
Sometimes it results parthenogenesis (单性生殖 ),
Drop of buds,flowers and fruits
Fruits developed remain very small and are of poor quality.
Deficiency symptoms
Boron deficient potatoes
Growth stunted; growing point killed;
leaves dull grayish green,changing to yellow before dying off,
Boron toxicity shown by narrow brown
rims on leaflets;
magnesium deficiency by intervenal
necrosis and withering
黄瓜缺硼,B deficiency of cucumber,older leave developed
yellow； new leave are distorted and appear mottled； Aborted
fruit (top); twisting and scarring；
? ?
? ?
B deficiency,Stems stiff; terminal buds die and
growths die back （ up is capsicum； bottom is
cucumber and tomato）
? 番茄果实缺硼：表面
有凹痕软木区，成熟
不平衡，类似缺钙。
? Fruits pitted and
corky areas in skin;
ripening uneven
Cauliflower Head Boron deficiency
Browning of curd
Longitudinal section,Browning of curd and
lesions in pith,(Not specific for boron; may be
due to other causes in the field) Secondary
infection of Bacillus Carotovorus,
Corky condition of epidermis (bottom)
? ?
? ?
? ?
? Young Sugar Beet Plant Boron deficiency
? Early stage of boron deficiency,Young leaves distorted
and fail to expand.（ left)
―Crown Rot―茎腐病 and death and distortion of young
leaves; older leaves cracking and distortion of laminae,
yellow pigment formation and severe marginal scorch.
(right)
? ?
? Table Beet Plants Boron deficiency
? Collapse of foliage,beginning with young leaves;
rotting of outer tissues of the roots,("Canker") ；
Transverse section,"Canker" lesions,mainly
in outer tissues,
Rough skin condition which may accompany
"Brown Heart" condition,
? 蕉青甘蓝缺硼,Swede Plant Boron deficiency
? Mottling and tinting of foliage and death of
growing point,(right)
? Rough skin condition which may accompany
"Brown Heart" condition,(middle and right)
?
? Runner Bean Stem and
Leaves Boron deficiency
? Stem thickened and stiff;
growing points die; leaves
slight chlorotic mottling.
Carrot Plants
Boron deficiency
Growth of young leaves restricted giving a
rosette effect,
older leaves orange tints; growing point
may die,
Crops sensitive to B deficiency
? Crops differ in their sensitivity to B deficiency,
? Most sensitive crops,Cruciferae（十字花科） such
as cabbage,turnips,brussels(抱子甘蓝）,sprouts,
cauliflower and Chenopodiaceae(藜科） such as
sugar beet and swede,
? Others crops sensitive to B deficiency,celery,
groundnut（落花生）,coffee,oil palm（油棕榈）,
cotton,sunflower,olive,and pines（松树）,
? Legumes and fruit trees have a high B requirement
? Graminaceous monocots have a low B requirement.
Boron concentrations of various plant groups
(Syworotkin 1958) B in μg/g DM
M o n o c o t s D i c o t s D i c o t s w i t h a l a t e x s y s t e m
B a r l e y 2, 3 P eas 22 D a n d e l i o n ( 蒲公英 ) 80
W h e a t 3, 3 B e e t s 49 E u p h o r b i a ( 大蕺属 ) 93
M a i z e 5, 0 L e t t u c e 70 P oppy ( 罂粟 ) 94
Boron toxicity
? The symptoms of B toxic often occurs
on the older leaves.
? Begin with chlorosis on the tips and
margins and finally spreads between
the lateral vein,followed by progressive
necrosis in the advantage stage.
? The leaves take on a scorch (焦枯）
appearance and drop prematurely.
B toxicity of Mellon（ left of up）
and sweet potato (bottom0
B toxicity,rice（ up）
?
? +B Symptoms of B
toxicity are first seen
in older leaves,They
include yellowing
between the
veins,followed by
necrosis,Note small
brown necrotic
spots,and large
areas of dead tissue
B toxic of cucumber in the greenhouse
Boron toxic soils
? Arid and semi-arid soils with high B
level
? B concentration in the irrigation water
>0.3-1mg/L for sensitive crops; 1-2mg/L
for semi tolerant plants and 2.1-4 mg/L
for tolerant plants
? Industrial pollution
Sensitivity of crops to B toxicity
? Sensitive crops,peach,grapes,kidney
beans(菜豆 ) and figs(无花果 )
? Semi-tolerant crops,barley,peas,
maize,potato,lucerne(苜蓿 ),tobacco,
and tomato
? Most tolerant crops,turnips(芜青 ),
sugarbeet and cotton.
Boron fertilizer
B or on s ou r c e C he m i c a l f or m ul a S ol ub i l i t y B ( % )
B or a x ( 硼砂 ) Na
2
B
4
O
7
· 10 H
2
O W a t e r s ol ub l e 11
B or i c a c i d H
3
BO
3
W a t e r s ol ub l e 17
B or on f r i t s ( 硼 玻璃 ) Na
2
B
4
· XH 2 O M od e r a t e l y s ol ub l e 10 - 17
S od i um t e t r a bo r a t e Na 2 B 4 O 7 · 5H 2 O W a t e r s ol ub l e 14
B or a t e - 65 Na
2
B
4
O
7
W a t e r s ol ub l e 20
S od i um pe nt a bo r a t e Na 2 B 10 O 16 · 10H 2 O W a t e r s ol ub l e 18
S ol ub or ( 硼砂 ) Na
2
B
4
O
7
· 5H 2 O + Na
2
B
10
O
16
· 10H
2
O W a t e r s ol ub l e
B or a t e d s up e r ph os pa t e
C ol e m a ni t e ( 硬 硼酸 钙 ) S l ow r e l e a s e
Application of boron fertilizer
1,Soil application
2.Foliage spray
early autumn or anthering
3,Application as starter or pop-up
Molybdenum
Soil molybdenum
? Content of Mo in soil
? 0.8-3.3 mg/kg in agriculture soil
? Soil derived from granitic rocks (花岗岩 ),
shells（贝壳）,slates（板岩） or
argillaceous schist（片岩） are often high in
Mo
? Highly weathered acids soils tends to be
deficient
? Soils formed from igneous rocks（火成岩）
and shale(页岩 ) and poorly drained neutral or
alkaline organic soils have high level Mo
Soil molybdenum
? Fraction of soil Mo
? Dissolved Mo
? Mo occluded with oxides
? Mo solids phases,including
molybdenite辉钼矿 (MoS2),powellite
(CaMoO4),ferrimolybdite水钼铁矿
(Fe2(MoO4)3 and PbMoO4,
? Mo associated with organic compounds.
Soil molybdenum
? Mo availability in soil
? Molybdate is the most prominent form in soil
solution above a pH about 4.
? Molybdate is absorbed by sequioxides and clay
minerals via ligand exchange similar to
phosphates,
? The Mo concentration in soil solution is usually
determined predominantly by soil pH and total
Mo content of the soil,
? As the pH falls the Mo soil solution concentration
decrease.
Soil molybdenum
? Soils derived from quartzic material,sandy
pebbly(多卵石的 ) alluviums(冲积物 ),and
sandy loam and soils with high anion
exchange capacity are often Mo deficiet.
? Peat soils
? Calcareous soil derived from loess and
alluvium
Mo in physiology
? Content of Mo in plant
? The Mo concentration of plant materials
is usually low and plants are adequately
supplied with less than 1 mg/kg dry
matter,Deficiency is usually under 0.2
mg/kg dry matter,
Mo concentration in different plants in μg Mo/g
in the dry matter (Johnson 1966)
L u c e r n e l e a v e s 0, 3 4 S u g a r b e e t t o p s 0, 7 2
P h a s e o l u s b e a n t o p s 0, 4 0 T o m a t o l e a v e s,h e a l t h y 0, 6 8
S p i n a c h l e a v e s 1, 6 0 T o m a t o l e a v e s,d e f i c i e n c y 0, 1 3
Mo in physiology
? Mo uptake and translocation
? Mo is absorbed by plants as molybdate.
? The uptake is depressed by the SO4-
and phosphate.
? Mo may possibly move in xylem as MoO42-,
as Mo-S amino acid complex or as a
molybdate complex with sugar or polyhydroxy
compounds.
? Mo is moderately mobile in plant,
Mo function in plant
? Mo is an essential component of nitrate
reductase and nitrogenase
? Mo plays another essential role in the N
metabolism in legumes such as soybean and
cowpea.—xanthine dehydrogenase (黄嘌呤脱
氢酶）
? Other functions
? Synthesis of vitamins
? IAA oxidase activity
? Phosphatase activity
? Chlorophyll structure stability
Symptoms of Mo deficiency
? Mo deficiency frequently begins in the
middle and older leaves.
? Interveinal mottling,marginal chlorosis
of the older leaves and upward curling
of the leaf margins are all typical,
? As the deficiency progress necrotic
spots appear at leaf tips and margins.
Symptoms of Mo deficiency
? In the cruciferae the lamella is not properly
formed and in the extreme case only the leaf
rib is present,like a whip,so the deficiency is
called,whiptail”
? Curd(胚乳） formation is also distorted
? In Mo deficiency maize the tasseling stage(抽
穗期） is delayed; flower fail to open and
grain size and viability is greatly reduced;
premature sprouting（萌发） of grains.
Mo deficiency of cauliflower,interveinal mottling,marginal chlorosis
of the older leaves and upward curling of leaf margins and tip
necrosis in early stage； in the serious deficiency,leaf lamella is
not properly formed and in extreme case only the leaf rib is present,
it is called whiptail）； curd formation is also distorted.
?
TOMATO PLANTS Molybdenum deficiency
Leaflets somewhat chlorotic,strongly incurled and die
back from tips,
Left,healthy leaf receiving molybdenum,Right:
Molybdenum deficient leaf; leaflets,incurled margins,
intervenal chlorotic motting and death of tips.
?
?
? Young Cabbage
Plants (Savoy)
Molybdenum
deficiency
? Leaves cupped and
show chlorotic
mottling,especially
around margins; tips
and margins develop
dead patches; plants
fail to heart,(Similar
to manganese toxicity；
Mo toxicity
? High Mo levels in fodder and a Mo concentration
of 5 to 10 mg Mo/kg in the dry matter is
dangerous to ruminants such as cattle,
? Molybdenosis (慢性钼中毒 ),diarrhoea（腹泻）,
depigmentation (褪色 ) of hair or wool,bone
formation and reduction in growth.
? Poorly drained soils derived from granitic (花岗岩）
alluvium and black shales ash on highly organic
soils.
Mo fertilizers
? Molybdenum trioxide MoO3 Mo 60%
? Ammonium
molybdate(NH4)6Mo7O24.4H2O
? Mo 54%
? Na molybdate Na2MoO4.2H2O Mo 38-
46%
? Molybdenized superphosphate
Application of Mo fertilizers
? Seed treat
? ７ g/ ha
? Soil apllication
? 0.01-0.5kg/ha
? Foliage spray
? 85g/ha
Chapter 14
General Characteristics
Nutrient Soil Content (kg/ha) Corn Removal (kg/ha)
Boron (B) 22-225 0.07
Copper (Cu) 2-450 0.06
Iron (Fe)
11,200 – 224,000 0.12
Manganese (Mn) 112-11,200 0.09
Molybdenum (Mo) 1-8 0.03
Zinc (Zn) 22-675 0.17
Micronutrients in Soils and Crops
? A,Micronutrients are required by all
plants but in smaller amounts
compared to the macronutrients,
? Deficiencies of micronutrients can
reduce growth just as much as
deficiencies of macronutrients,
Remember the ―Law of the Minimum‖.
General Characteristics
B The amount of micronutrient that is
needed by the plant can have a narrow
range,If the amount of micronutrient is
too high,it is possible for toxicity to
occur.
Available forms
1,Cations,Fe2+,Fe3+,Mn2+,Zn2+,Cu2+
2,Anions,MoO42-,Cl-
3,Neutral,H3BO3
General Characteristics
Micronutrient function in plants
1,Enzymes and coenzymes
a) Structural component of enzymes
b) Involved in the activation and regulation
of enzymes
2,Oxidation and reduction reactions
Micronutrients are involved in electron
transport
Micronutrient transformations in the soil
1,The transformations that micronutrients undergo in
the soil vary depending on the nutrient,but overall,
the reactions are similar to what has already been
discussed for macronutrients.
a) Mineralization and immobilization
b) Adsorption and desorption to clay or organic
matter surfaces
c) Precipitation and dissolution of secondary
minerals
Micronutrient transformations in the soil
2,Micronutrients undergo one
transformation that is quite different
from the transformations that we
discussed for the macronutrients,That
transformation is called chelation,
a) The word chelate means ―claw‖,Chelation
refers to the process in which organic molecules
in the soil form a complex with micronutrient ions,
b) The chelated micronutrients are carried by
mass flow and diffusion to the root surface.
The chelation process in the soil
c) The chelate is broken down in rhizosphere,
The micronutrient is taken up by the root and
the organic molecule diffuses away,
d) The organic molecule can complex with
more micronutrients and the process is
repeated,
The chelation process in the soil
e) There is still a lot about the chelation of micronutrients that
is unknown,The organic molecule that forms the chelate
may be derived from:
Natural chelates
(1) Organic compounds released by the roots or soil
microorganism,such as Siderophores高铁载体 and
phytosiderophores植物高铁载体
(2) Compounds released during the decomposition of soil
organic matter,such as fulvic acids
(3) Man-made chelates,EDTA,DTPA EDDHA etc
The chelation process in the soil
Soluble chelates increase the
availability of micronutrient cations,Fe,
Zn,Mn,and Cu,The chelates help
protect the ions from precipitation or
adsorption reactions,
The chelation process in the soil
a) Solubility of the micronutrient (affected by
factors such as pH)
b) Percent of exchange sites that are
occupied by the micronutrient
c) Soil organic matter
(1) Affects the balance between adsorption and
desorption
(2) Organic matter is also involved in the
chelation process
Factors that affect micronutrient availability
Iron
? Fe in the soil
Fe is one of the most abundant elements
in the surface of the earth,It makes up about
5% weight of the earth’s crust and is
invariably present in all soils.
Iron forms in soil
? Mineral bearing iron
? Primary mineral:
? olivine,augite(辉石 ),hornblende and biotite(黑云母 ).
? Minerals Fe oxides
? Geothite (α-FeOOH针铁矿 ),haematite（赤铁矿 ) and
ferrihydrate（ HFe5O8·4H2O水化铁） etc
Iron in the soil solution
1,Soil solution concentrations are very low,
The concentration of Fe3+ in the soil is
~10-15 to 10-20 M,
? Soluble inorganic forms include Fe3+,Fe(OH)2+,
Fe(OH)2+ and Fe2+
? Iron solubility is largely controlled by the
pH and Eh.
? Fe3+ +3OH-= Fe(OH)3
? At higher pH levels Fe3+ activity in solution decrease
1000 fold for each pH unit rise
In aerobic soils,Fe2+ is oxide to Fe3+,
and formation of Fe(OH)3 precipitation.
In water-saturated soils (anaerobic),
Fe3+ is converted into Fe2+,which
increase Fe solubility.
Fe(OH)3 +e-+3H+ Fe2+ +3H2O
Iron in the soil solution
Siderophores and phytosiderophores
Siderophores are a kinds of
organic substance (such as
nicotinamine (烟酰胺 ),mugineic acid麦
根酸 and avenic acid etc) produced by
the bacteria,fungi and plant),which can
form organic complexes or chelates with
Fe3+,and increase the movement of
iron in soil.
Characteristics of siderophores
they are molecules with a high
affinity for Fe3+,and removes the Fe from
minerals and contributes their dissolution.
these Fe-chelates are highly soluble
and are stable over a wide pH range.
they are of crucial importance for the
Fe transport in soils and the Fe supply of
plants.
Plant uptake of Fe
1,Plants can take up both Fe2+ and Fe3+,
In general,Fe2+ pass through a species
channel of PM,Fe3+ is reduced to Fe2+
before absorption occurs,Fe3+ uptake is
important for grasses
Phytosiderophores molecular is take up
by specific transporters located in PM of
graminaceous禾本科 monocots root,and Fe
is reduced in cells.
Factors that affect Fe uptake
1,Plants have different abilities to take up Fe
from the soil solution
Not only different species (wheat vs,bean) but even
different genotypes.
2,pH
Fe3+ reduction requires a pH of about 5 at the
apoplastic site of the reductase,
The Fe uptake of general plant is affected by the pH,but
Fe uptake of graminaceous monocots is little affected by pH.
3,Ability of Fe3+ reduction in the root
Effect of pH in the nutrients solution and N sources on the
Fe concentrations in leaves and roots and chlorophyll
concentration in the youngest leaves of helimanthus
annuus (Kosegarten et al 1998)
T r e a t me n t C h l o ro p h y l l,m g / g f r,w t, L e a f,μ g F e / g d ry w t, R oot,μ g F e / g d ry w t,
NH 4 N O 3,p H 4,c o n t r o l 1, 5 0 7 0, 8 156
NH 4 N O 3,p H 6, 5 0, 9 5 *** 3 2, 5 * * 307 *
N O 3
-
,p H 6, 0 0, 2 8 * * * 2 9, 1 * * 351 **
*,* *,* * * r e p r e s e n t s i g n i f i c a n t l y f r o m t h e c o n t r o l a t p < 0, 0 5,0, 0 1 a n d 0, 0 0 1,r e s p e c t i v e l y
Translocation of iron
? The Fe2+ in the cytosol is presumably
oxidized in transport into the xylem.
? Long- distance transport in the xylem is
Fe3+ complex when an excess of citrate in
the xylem.
? In the phloem and in the symplasm Fe is
transported as an nicotianamin,
Fe concentration in the plant
Fe concentrations in dry plant tissue
are commonly around 50-100 μg/g
(compared to N which is typically 10,000-
50,000 μg/g
Most of Fe is in the vegetative parts,
grains and tubes are often considerably low.
The content of iron in the plant is
effected by the soil iron availability,
1,Fe is important in the process of chlorophyll and
haem formation in plants
text book p392
2,Fe is required for electron transport in
photosynthesis,
It is an important part of several molecules
that are involved in photosynthesis,
Iron sulphur proteins or ferredoxin and ferritin(铁
蛋白 )
Roles of iron in plant
Roles of iron in the plant
3,Chelate complex Fe is an important electron
acceptor in redox reactions
Haem is prosthetic groups辅基 of several enzymes
(catalase,peroxides,cytochrome oxidase etc.),
4,Nitrogenase comprises an Fe protein and FeMo
protein;
5,Ribonucleotide reductase,It is required of
synthesis of DNA and RNA,which is required for
the synthesis of proteins.
Fe deficiency symptoms
1,Interveinal yellowing and chlorosis of whole leaves and
emerging leaves.
Symptoms appear on youngest upper leaves The leaves are
yellow,with the veins remaining green,
2,Whole leaves become chlorotic and pale and reduction of
leave.
3,Not all species are equally susceptible to Fe deficiency
Calcifuge species(避钙植物） is susceptible to Fe
chlorosis;
The most important commercial crops affected are
citrus,deciduous fruit trees落叶果树 and vine;
Field beans,soybeans,legumes,and tomato etc,
Iron deficiency in soybeans
Iron deficiency in rice
Wheat Plants Iron deficiency
Severe chlorosis of leaves,
most severe on younger growths;
die-back of chlorotic leaves
Oat Plants Iron deficiency
Young leaves severe chlorosis;
chlorosis begins as interveinal stripes,
越橘
Fe deficiency of grape leaves (up)
Fe deficiency of pear (left and middle of bottom),and apple tree (right of bottom)
Tip leaves chlorotic; small veins show as fine network in early stages; margins
develop brown patches
Potato Foliage
Iron deficiency
Young leaver strongly chlorotic;
veins may remain green;
margins and tips brown patches,
Potato Foliage
Iron deficiency
Young leaver strongly chlorotic;
veins may remain green;
margins and tips brown patches,
TOMATO FOLIAGE
Iron deficiency
Tip leaves,especially basal
areas of leaflets,
intense chlorotic mottling; stem
near tip also yellow,
Cabbage Plant (Savoy皱叶
甘兰 )
Iron deficiency
Severe chlorosis of leaves
beginning as a chlorotic
mottling色斑,
? 水稻铁中
毒：青铜
色叶片
bronzing
leave or
bronzed
disease
Lime induced chlorosis
? Iron chlorosis may result from an absolute
Fe deficiency in soil,such as organic soils
and degraded sandy soils,But such cases
are rare.
? However,iron chlorosis occurs frequently
on the calcareous or saline and sodic soils,
The chlorosis is not caused by absolute
Fe deficiency,The Fe concentration in the
chlorotic leaves can be higher than in the
green leaves,Why?
Lime induced chlorosis
? Calcareous soils,high pH and high HCO3-
concentrations in soil solution may depress or
even block F3+ reduction in the root apoplast,
? The nitrate nutrition is predominately in
Calcareous soils,which induce high apoplastic
leaf pH,so Fe3+ reduction in the leaf apoplast is
restricted and hence the uptake of Fe from the
apolast into the cytosol impaired.
? Spraying chlorotic leaves with dilute acids results
in regreening,So does fusicoccin ( 壳梭孢素 )as
well as IAA
Effect of spraying Fe-EDDHA or dilute H2SO4 for
curing Fe chlorosis on chlorophyll concentration and
pod yield of Pisum sativum (Shau 1987)T r e a t me n t C h l o r o p h y l l,mg / g / f r e s h w e i g h t P od y i e l d M g / h a
C o n t r o l,n o s p r a y i n g 1, 3 7 1, 7 9
H 2 SO 4 1, 8 3 3, 3 6
Fe - E D D H 1, 7 8 3, 1 5
P <0,0 5 0, 6 7 6 0, 6 7 6
Common Fe Fertilizers
1,Ferrous sulfate,FeSO4·7H2O,(20% Fe)
a) applied to foliage as a solution
b) injected into the tree trunk
2,Iron oxalate,Fe2(C2O4)3,(30% Fe)
3,Iron citrate,FeC6H5O7·X H2O,(16%-
18% Fe)
Common Fe Fertilizers
3,Chelated iron
Chelated iron compounds consist of an
organic molecule that binds iron and makes it
solubility in soil solution and more available to
plants,
FeEDDHA,Fe 6%
FeDTPA,Fe10%
FeEDTA,Fe 9-12%
HEDTA,Fe 5-9%
b) Chelated compounds must be placed into
the root zone to be most effective,Or foliage
application.
Applications should be made in the
spring to coincide with the beginning of
growth.
In most cases,it is necessary to treat the
soil every year.
Common Fe Fertilizers
Management strategies
? A,Soil application can be helpful when the pH is
low,but not at high pH,
? B,Alternative methods of Fe-fertilization include:
1,Foliar application
2,Seed coating
3,Injecting Fe into the tree trunk
Other management strategies
1,Lower the pH of the soil (increases
soluble Fe
2,Combined the organic matter content
and FeSO4 together.
3,Choose varieties that are not so
sensitive to iron deficiencies.
Zinc
Soil Zinc
The total amount of Zn in the soil is
relatively small,The average Zn content
of the soil is 17 to160μg Zn/g soil.
The level of Zn in soils is very much
related to the parent materials.
Basic igneous rocks > siliceous parent
materials
sometimes,pollution soil have high Zn
levels
zinc content in soil
Soil Zinc
primary and secondary soil minerals:
augite (辉石 ）, hornblende,and biotite (黑云母 ）
salts,
ZnS,Sphalerite (ZnFe)S 闪锌矿, smithsonite
(ZnCO3)菱锌矿 willemite (Zn2SiO4)硅锌矿
Zinc fraction in soil
Soil Zinc
Soil solution Zn
1,the Zn concentration is very low and in
the 3╳ 10-5 to 5 ╳ 10-3mol/l.
2,forms of Zn in soil solution
Zn2+,ZnOH+ or ZnCI+
Most of the Zn in the soil solution is
usually in the chelated form
Soil Zinc
Exchange Zn
Clay minerals and organic matter have
exchange site of Zn ions.
Specific adsorption of Zn2+ by carbonate:
Magnesite (菱镁矿） >dolomite（白云石） >calcite（方解石）
Adsorption and occlusion of Zn by carbonate
are major cause of poor Zn availability and the
appearance of Zn deficiency on calcareous soils.
Soil Zinc
? Organic Zn
? Zn can interact with organic matter in soil
? Soluble Zn organic complexes is about
60% of total Zn in soil solution.
? Amino acids,organic acids and fulvic
acids富哩酸 complexes with Zn are
soluble; but insoluble organic complexes
are derive from humic acid胡敏酸,
Soil Zinc
? pH:
Soluble Zn+2 is ~100 times lower with a pH
increase of 1 unit
organic matter
Zn complexes can either increase or decrease
the availability of Zn to the plant.
carbonate content
History of arable soil
Excess application P fertilizers or iron Mn
etc
Factors affecting soil Zn availability
Zinc in plants
? Zn Content in plant
? For most plant species Zn
concentrations in leaves below 10-15 μg
Zn/g dry matter are indicated of Zn
deficiency and concentration in the range
of 20 to 100 μg Zn/g dry matter are
sufficiency,
Zinc in plants
Uptake and translocation
The uptake may be as facilitated
diffusion through membrane channels
or mediated by specific transporters.
The uptake is strongly inhibited by
the Cu,the Fe,Mn and alkaline earths
cations碱土金属离子 etc.
And is reduced by low temperature.
Zinc in plants
? Translocation
? Zn is not bound to stable ligand.
? It is translocated as zinc citrate
complexes
? Zn is phloem-mobile,but its
translocation is varies among different
plants,
? In the high Zn level,excess Zn is
deposited to a large extent in the older
leaves
Zinc in plants
Function of Zn in plants
1,Activates 300 enzymes
Carbonic anhydrase( 碳 酸 酐 酶 ） is
particularly important for C4-species.
Alcohol dehydrogenase is important in
root under anaerobic conditions.
Cu-Zn superoxide dismutase (SOD) is
required for the detoxification of the
superoxide radical超氧自由基, It is important
to resist the sunscald (日灼病 ）
Enzymes involved in the carbohydrate
metabolism.
Zinc in plants
Function of Zn in plants
2,Necessary for the plant hormone (for
example IAA)
In Zn deficient plant it is low rates of
stem elongation,low auxin activities and
low trytophan (色氨酸 ）
3,Zinc is very closely in the N metabolism of
plant.
RNA polymerase contains Zn
Zinc deficiency affected the structural
integrity of the cytoplasmic ribosomes.
Deficiency symptoms
1,Stunted (reduced) growth
Unevenly distributed clusters or rosettes
of small stiff leaves (Small,narrow,thick
leaves) are formed at the ends of the
young shoots,Frequently the shoots die off
and leaves fall prematurely.
Apple tree,rosette and little leaf.小叶病
与簇叶病,
Fewer bud,bark is rough and brittle
Deficiency symptoms
2,Chlorosis in the interveinal areas of the
leaf
In the monocots chlorotic bands form on
either side of midrib of the leaf which later
become necrotic,The symptoms appears on
young leaves.
In most case,the deficiency symptoms of
vegetable crops is characterized by short
internodes and chlorotic areas in older leaves.
Sometimes chlorosis also appears in younger
leaves.
Zinc deficiency in corn
Zinc deficiency in canola (chlorotic
mottling and than necrosis)
Zinc deficiency of citrus
spring
summer
Zinc deficiency of rice
?
? Center,healthy shoot from
zinc deficient apple tree;
? Left and Right,shoots
showing zinc deficiency
symptoms; buds along
shoots fail to develop,
leaves small and narrow
("Little Leaf" condition)
and tend to form rosettes
at tips of shoots,
Zinc toxicity and tolerance
? Excess Zn supply results in reduction of
root and leaf expansion which is followed
by chlorosis,Red-brown pigment was
formed under conditions of excess Zn in
soya beans,
? Some plants species are Zn tolerant,They
can accumulated 600 to 7800 μg Zn/g dry
matter,
?
? Sugar Beet Plants
Zinc toxicity
? Growth severely
stunted; young leaves
show chlorotic iron
deficiency symptoms
followed by severe
intervenal necrosis
? Excessive Zn of
cucumber,dark
green of older
leave (left).
? Younger leave
shows slight
green with
interveinal
brown spot like
pinhole
Conditions that may have Zn deficiencies
A,Soils with a high pH (low Zn solubility)
B,Fine-textured soils (Zn adsorption)
C,Cool,wet conditions
D,High levels of Cu,Fe,Mn or P can
cause a Zn deficiency
E,Some crops are more sensitive than
others
1,Corn and beans are sensitive
2,Sensitive crops following sugar beets
may have a Zn deficiency.
Conditions that may have Zn deficiencies
Zinc fertilizer
A,Kinds of Zn fertilizer
1,Manure supplies Zn and organic molecules
for chelation
2,ZnSO4 (35% Zn) is most common fertilizer
3,Chelated zinc
Application of Zn fertilizer
1,Zn may be applied to the soil or to the
foliage
2,Banding is usually more efficient than
broadcasting – but don’t band P and
Zn together.
Zinc fertilizer
Copper
Copper in the soil
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.
Copper fractions in soil
? Minerals
? Largest fraction of Cu is usually present in the crystal
lattices of primary and secondary minerals,such as
olivine,hornblende,picrites辉石,biotite,feldspar,
chalcopyrite黄铜矿 etc.
?
Copper fractions in soil
? 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 (层状硅酸盐 ),
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
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)
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 (波
尔多液 ）,
The factors controlling Cu availability in soils
So Cu deficiency often occurs on the
Cu inherently low soils such as sandy
podzolic soils灰化土 and soils developed
on parent materials poor in Cu; organic
soil and peaty soil calcareous soils high in
clay content.
Reclamation disease 开垦病
Copper in plants
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 (花 ） are normally very high in Cu.
Crops species differ in their sensitivity to Cu
deficiency.
The most responsive crops,oats,spinach,wheat,
and lucerne (紫花苜蓿 )
Medium range,cabbage,cauliflower,sugar beet
and maize
Low response crops,beans,grass,potatoes and
soya beans
Copper in plants
? Uptake and transport
? The mechanism of Cu uptake is not yet
clear,But Cu2+ must be reduced
before is transport across the PM
? Cu uptake appears to be metabolically
mediated process
? Zn strong inhibit the Copper uptake and
vice versa
Copper in plants
? 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
deficiency plants Cu is relatively immobile.
? Cu is transported in the form of anionic
Cu complex.
Function of Cu in plants
1,Important component of many enzymes
The most common of the three types of superoxide
dismutase iosenzymes contains Cu and Zn (Cu-ZnSOD)
Cytochrome c oxidase is one of the most well studied
of Cu containing enzymes in the mitochondrial transport
chain.
The enzymes phenolase (tyrosinase酪氨酸氧化酶
and polyphenol oxidase多酚氧化酶 )
Ascorbic acid oxidase
Amine oxidase which catalyze oxidative deamination.
Function of Cu in plants
2,Necessary for photosynthesis
Blue protein or plastocyanin 质体蓝素
(2Cu/molecular) is essential redoxsystem of the
photosynthesis e- transport chain.
3,Involved in the lignification of cell walls
Phenolase ( 酚酶 ) and laccase ( 漆酶 ) are
involved in lignin synthesis.
Function of Cu in plants
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 (开花期 ） 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.
Copper deficiency symptoms
In cereals crops deficiency shows
first in the leaf tips at tillering (分蘖
期 ),The tips becomes white and leaves
are narrow and twisted,The growth of
internodes is depressed; excessive
tiller occurs; ear（ 小穗 ） and panicle(圆
锥花序 ） formation is absent in severe
conditions,Or ear are not fully developed
and may be partially blind in less
deficiency.
Copper deficiency symptoms
? In Cu deficient trees the development of
― pendula‖(摇摆） forms may occurs.
? In N application soil plant is easily to
lodging if Cu deficient.
Copper deficiency in barley
Pigtail whip tail of barley
shows copper deficiency
Left normal wheat,Right wheat with
severe copper deficiency symptoms
upright empty headed Park wheat at right is grown on
0.6 ppm DTPA Cu soil,
At left,same crop grown on soil amended with 12 lb
Cu per ac as CuSO4,
Yields were 19 bu per ac vs 51 bu per acre
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黑变病,
Toxic of Cu
? 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 of root
growth is one of most rapid response to
toxic Cu levels
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
Copper fertilizer
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
T a b l e 7, P a r k w h e a t r e s p o n s e t o c o p p e r f e r t i l i z a t i o n n e a r T o f i e l d,A l b e r t a,*
M e t h od of
c op p e r ap p l i c at i on
Y i e l d b u / ac r e
3 yr, A vg,
C on t r ol 44
C op pe r c he l a t e s oi l s pr a y 59
C op pe r s ul ph a t e s e e d - r o w 56
C op pe r s ul ph a t e ba nd 50
C op pe r s ul ph a t e br oa dc a s t 60
*O ne - t i m e a pp l i c a t i on of C u c he l a t e ( 1 l b,C u/ a c r e a s C u - E D T A ) a nd C u s ul ph a t e ( 3 l b,C u/ a c r e a s
C u s ul ph a t e ),
Cu concentrations of organic manures and
wastes (Dam Kofoed 1980)
F r e s h w e i gh t,μ g g
- 1
D r y w e i gh t,μ g g
- 1
C a t t l e m a nu r e 9 34
P i g m a nu r e 21 86
P ou l t r y m a nu r e 30 69
S l ur r y,pi g 18 265
S l ur r y,c a t t l e 4 43
S l ud ge ho us e ho l d 46 1 13
S l ud ge,i nd us t r y 353 1477
? 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
Application
Manganese
Manganese in the soil
? 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 软锰矿,manganite or MnO(OH)水
锰矿 ),clays,oxides,and hydroxides.
Manganese in the soil
? 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+
Oxdation/reduction processes of Manganese in the soil
Mn2+ Mn2O3
MnO2·nH2O
MnO2
Aerobic and OH-
Aerobic
and OH-
dehydrate
Aerobic
and OH-
Anaerobic
and H+
Factors of control of Mn availability in soil
? Redox conditions
? as Eh increase,the Mn availability decrease
? pH
? pH>5 to 6,the reduction rate decrease by a factor 10 to
100
? Forms of Mn oxide
? amorphous > crystalline
? Organic matter large organic matter reserves are
particularly prone to Mn deficiency
? Microbial activity pH dependent (pH=7)
Effect of liming and a three day period of flooding
on dry matter yield and Mn concentrations in
lucerne (Graven et al,1965)
T r e a t m e n t
g C a C O 3 / p o t
F l o o d i n g g,d r y m a t t e r / p o t
M n c o n c e n t r a t i o n
Μ g / d r y m a t t e r
0 - 3, 1 4 2 6
0 + 1, 2 6 0 6 7
2 0 - 5, 7 9 9
2 0 + 3, 0 9 5 4
Manganese in plants
? Mn uptake and translocation
? Mn uptake occurs in the forms of Mn2+ by facilitated
diffusion presumably.
? Mg2 + and Ca2 + depress Mn2+ uptake
? Mn 2+ depress the Fe uptake
? Mn is relatively immobile in the plant and
is scarsely translocated in the phloem.
? Mn is preferentially translocated to meristem.
? Si enhanced the distribution of Mn in barley
plants
Manganese in plants
? 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 (真核细胞）
Manganese in plants
3,Photosynthesis
Involved in the splitting of H2O and O2 evolution in
photosynthesis – Hill reaction
Manganese in plants
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
Deficiency symptoms
Chloroplasts are the most sensitive of all
organelles to the Mn deficiency and
disorganization of lamellar( 片层 ） 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‖ 灰斑病
Wheat,Oats,Barley
Manganese deficiency
Field comparison of susceptibility,
Oats (center) more susceptible than barley (left) and wheat (right).
Oat Leaves and Heads Manganese deficiency (right),Leaves,grayish-
brown elongated specks and streaks,most prevalent in basal halves;
breaking of leaves with distal areas remaining green empty panicles.
?
Irregular,grayish-brown
lesions,which coalesce
and bring about collapse
of leaf (gray speck
symptoms灰斑病 ) (left),
Rye and wheat Mn deficiency,interveinal chlirotic
spot and stripe on the middle and basal halves
? ?
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.
Apple,Variety,Early Victoria,Leaves
severe chlorosis over most of tree;
young leaves of terminal shoots not as
severely affected as older leaves.
Apple Foliage Manganese deficiency
Leaves intervenal chlorosis progressing
from margins towards midrib.
?
?
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)
? ?
?
Manganese toxic
? 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
toxicity,
? The toxicity symptoms are generally
characterized by brown spots of MnO2 in
older leaves surrounded by chlorotic areas.
Mn toxicity of orange and lemon
Mn toxicity of vegetable rice
Manganese toxic
? 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（分枝，分蘖增加）,
? Some times Mn excess can induce a
deficiency of other mineral nutrients
such as Fe,Mg and Ca.
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(灰化土 ) and sandy soils
etc
6,Crops
oats and peas are the most sensitive to Mn
deficiency; other sensitive crops are,apple,cherry,
citrus,raspberry(悬钩子 ),and sugar beet
Manganese Fertilizer
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 %
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
Kinds of manganese fertilizer
Boron
Soil boron
Total boron in the soil
The content of B in the soil ranges
between 20-200 mg/kg dry weight,Most
of which is inaccessible to plants.
Boron in the soil solution
1,Between pH 5 and 9,H3BO3 is the
dominant form of B in the soil solution.
2,The pH of the soil solution and the
amount of clay,oxides,and organic
matter are important factors that affect
B availability.
Soil boron fraction
? B containing Minerals
? Tourmaline (30-40 mg B/kg) and hydrated
minerals
? Absorbed B
? AI and Fe oxides,clay minerals,calcium
carbonate,and organic matter
? Ligand exchange,
kaolinite>montmorillonite>illite
Soil boron fraction
? Organic matter bounding B
? the sorption capacity for B in composed
organic matter is about 4 times greater than
for soil or clay,It is believed to be ligand
exchange.
? Hot water soluble B (0.5-2.0 mg B/L)
? Soluble B consists mainly of boric acid
which under most soil pH conditions (pH 4-8)
? B(OH)3 + H2O B(OH)4-; pK4=9.2
Soil boron fraction
Factors affecting boron availability
1,pH
Absorption of B is closely dependent on soil
pH,adsorption increase the pH range 5-9
2,B leaching
In acid,sandy soil or podzolic soil,B is easily
leached from soil; but in arid and semiarid regions,
B may accumulate to toxic concentration.
3,Organic matter
Native B and hot water soluble B in soil are
significantly correlated with organic C content.
Effect of soil pH and carbonate on the proportion of
sugar beet infected by crown and heart rot
(scheffer and Welte 1955)
P e r c e n t a g e o f s u g a r b e e t
pH C a r b o n a t e,%
H e a l t h y I n f e c t e d d e a d
6, 7 0, 1 100 0 0
7, 0 0, 1 99 1, 0 0
7, 5 0, 3 46 40 14
8, 1 1 4, 4 0 25 75
B deficient Soils
? Soils developed from sandstones and acid
igneous rocks
? Spodosol灰土 and podzols 灰壤
? Sometimes Andosols,Lithosols 石质土 and
Luvisols 淋溶土
? Sandy soil
? Liming acids with marginal B
concentrations
? Hot water soluble B <0.5 mg/L
Boron in plant
Uptake
B uptake is a possible combination of
active transport as esters with cis diols (顺式 二
醇 ) and passive diffusion as undissociated boric
acid,
But the exact nature of boric acid
transport across cell membrane is still not
totally resolved.
B in plant
Translocation
To most of plant species,B is translocated
through the xylems,and limited phloem,It is
controlled by the transpiration flow.
B is not readily transported in the plant,
Deficiencies occur first in the growing points and
young leaves.
But in some species,such as celery,carrot,
bean,and cauliflowers,apple,pear,and apricot杏,
B is mobile and is transported as a complex with
polyols (多元醇）,
Function of B in the plant
? Cell walls
? B is now believed to play a key role in
the structure and integrity of cell walls,
The chemical composition and
ultrastructure of cell walls are quickly
affected by a lack of B.
? The role of B in cell walls is cross
linking of pectic polymers (B-RG）,
? It is important to cell wall structure.
Function of B in the plant
? Membrane function
? 1.The effects of B are thus mediated either directly
or indirectly by the plasmamembrane bound H+
pumping ATPase.
? 2.The effects of B are primarily on
plasmmembrane itself (Cakmak and R?mheld
1997),
? B stabilizes the structure of plasma membrane by
complexing membrane compounds containing cis-diol
groups such as glycoproteins and glycolipids to keep
channels and enzymes at optimum conforation within the
membrane,
? 3.B exerts its most important influence at the
cell/plasma interphase.
Function of B in the plant
Other functions
Pollination
B was associated with the higher growth
rate of pollen tubes.
Root elongation
IAA levels is regulated by the B via IAA
oxidase activity
? Meristematic activity
? synthesis of N-bases such as uracil
Deficiency symptoms
1,Abnormal or retarded growth of apical
growing points,in advantage stage,death
of the terminal growing points
2,Stems have an unusual shape,They may
become thick and crack.
3,Youngest leaves are misshapen,wrinkled
and are often thicker and of a darkish blue-
green color,Irregular chlorosis between
the intercostal veins肋间脉 occur.
4,The roots may grow in a very unusual way.
In turnips芜青 and swedes甘蓝,B deficiency result in
glassy like root which are hollow and cracked
5,Flower and fruit formation is restricted or inhibited.
The tissue of the fruit may have some soft,brown spots,
Sometimes it results parthenogenesis (单性生殖 ),
Drop of buds,flowers and fruits
Fruits developed remain very small and are of poor quality.
Deficiency symptoms
Boron deficient potatoes
Growth stunted; growing point killed;
leaves dull grayish green,changing to yellow before dying off,
Boron toxicity shown by narrow brown
rims on leaflets;
magnesium deficiency by intervenal
necrosis and withering
黄瓜缺硼,B deficiency of cucumber,older leave developed
yellow； new leave are distorted and appear mottled； Aborted
fruit (top); twisting and scarring；
? ?
? ?
B deficiency,Stems stiff; terminal buds die and
growths die back （ up is capsicum； bottom is
cucumber and tomato）
? 番茄果实缺硼：表面
有凹痕软木区，成熟
不平衡，类似缺钙。
? Fruits pitted and
corky areas in skin;
ripening uneven
Cauliflower Head Boron deficiency
Browning of curd
Longitudinal section,Browning of curd and
lesions in pith,(Not specific for boron; may be
due to other causes in the field) Secondary
infection of Bacillus Carotovorus,
Corky condition of epidermis (bottom)
? ?
? ?
? ?
? Young Sugar Beet Plant Boron deficiency
? Early stage of boron deficiency,Young leaves distorted
and fail to expand.（ left)
―Crown Rot―茎腐病 and death and distortion of young
leaves; older leaves cracking and distortion of laminae,
yellow pigment formation and severe marginal scorch.
(right)
? ?
? Table Beet Plants Boron deficiency
? Collapse of foliage,beginning with young leaves;
rotting of outer tissues of the roots,("Canker") ；
Transverse section,"Canker" lesions,mainly
in outer tissues,
Rough skin condition which may accompany
"Brown Heart" condition,
? 蕉青甘蓝缺硼,Swede Plant Boron deficiency
? Mottling and tinting of foliage and death of
growing point,(right)
? Rough skin condition which may accompany
"Brown Heart" condition,(middle and right)
?
? Runner Bean Stem and
Leaves Boron deficiency
? Stem thickened and stiff;
growing points die; leaves
slight chlorotic mottling.
Carrot Plants
Boron deficiency
Growth of young leaves restricted giving a
rosette effect,
older leaves orange tints; growing point
may die,
Crops sensitive to B deficiency
? Crops differ in their sensitivity to B deficiency,
? Most sensitive crops,Cruciferae（十字花科） such
as cabbage,turnips,brussels(抱子甘蓝）,sprouts,
cauliflower and Chenopodiaceae(藜科） such as
sugar beet and swede,
? Others crops sensitive to B deficiency,celery,
groundnut（落花生）,coffee,oil palm（油棕榈）,
cotton,sunflower,olive,and pines（松树）,
? Legumes and fruit trees have a high B requirement
? Graminaceous monocots have a low B requirement.
Boron concentrations of various plant groups
(Syworotkin 1958) B in μg/g DM
M o n o c o t s D i c o t s D i c o t s w i t h a l a t e x s y s t e m
B a r l e y 2, 3 P eas 22 D a n d e l i o n ( 蒲公英 ) 80
W h e a t 3, 3 B e e t s 49 E u p h o r b i a ( 大蕺属 ) 93
M a i z e 5, 0 L e t t u c e 70 P oppy ( 罂粟 ) 94
Boron toxicity
? The symptoms of B toxic often occurs
on the older leaves.
? Begin with chlorosis on the tips and
margins and finally spreads between
the lateral vein,followed by progressive
necrosis in the advantage stage.
? The leaves take on a scorch (焦枯）
appearance and drop prematurely.
B toxicity of Mellon（ left of up）
and sweet potato (bottom0
B toxicity,rice（ up）
?
? +B Symptoms of B
toxicity are first seen
in older leaves,They
include yellowing
between the
veins,followed by
necrosis,Note small
brown necrotic
spots,and large
areas of dead tissue
B toxic of cucumber in the greenhouse
Boron toxic soils
? Arid and semi-arid soils with high B
level
? B concentration in the irrigation water
>0.3-1mg/L for sensitive crops; 1-2mg/L
for semi tolerant plants and 2.1-4 mg/L
for tolerant plants
? Industrial pollution
Sensitivity of crops to B toxicity
? Sensitive crops,peach,grapes,kidney
beans(菜豆 ) and figs(无花果 )
? Semi-tolerant crops,barley,peas,
maize,potato,lucerne(苜蓿 ),tobacco,
and tomato
? Most tolerant crops,turnips(芜青 ),
sugarbeet and cotton.
Boron fertilizer
B or on s ou r c e C he m i c a l f or m ul a S ol ub i l i t y B ( % )
B or a x ( 硼砂 ) Na
2
B
4
O
7
· 10 H
2
O W a t e r s ol ub l e 11
B or i c a c i d H
3
BO
3
W a t e r s ol ub l e 17
B or on f r i t s ( 硼 玻璃 ) Na
2
B
4
· XH 2 O M od e r a t e l y s ol ub l e 10 - 17
S od i um t e t r a bo r a t e Na 2 B 4 O 7 · 5H 2 O W a t e r s ol ub l e 14
B or a t e - 65 Na
2
B
4
O
7
W a t e r s ol ub l e 20
S od i um pe nt a bo r a t e Na 2 B 10 O 16 · 10H 2 O W a t e r s ol ub l e 18
S ol ub or ( 硼砂 ) Na
2
B
4
O
7
· 5H 2 O + Na
2
B
10
O
16
· 10H
2
O W a t e r s ol ub l e
B or a t e d s up e r ph os pa t e
C ol e m a ni t e ( 硬 硼酸 钙 ) S l ow r e l e a s e
Application of boron fertilizer
1,Soil application
2.Foliage spray
early autumn or anthering
3,Application as starter or pop-up
Molybdenum
Soil molybdenum
? Content of Mo in soil
? 0.8-3.3 mg/kg in agriculture soil
? Soil derived from granitic rocks (花岗岩 ),
shells（贝壳）,slates（板岩） or
argillaceous schist（片岩） are often high in
Mo
? Highly weathered acids soils tends to be
deficient
? Soils formed from igneous rocks（火成岩）
and shale(页岩 ) and poorly drained neutral or
alkaline organic soils have high level Mo
Soil molybdenum
? Fraction of soil Mo
? Dissolved Mo
? Mo occluded with oxides
? Mo solids phases,including
molybdenite辉钼矿 (MoS2),powellite
(CaMoO4),ferrimolybdite水钼铁矿
(Fe2(MoO4)3 and PbMoO4,
? Mo associated with organic compounds.
Soil molybdenum
? Mo availability in soil
? Molybdate is the most prominent form in soil
solution above a pH about 4.
? Molybdate is absorbed by sequioxides and clay
minerals via ligand exchange similar to
phosphates,
? The Mo concentration in soil solution is usually
determined predominantly by soil pH and total
Mo content of the soil,
? As the pH falls the Mo soil solution concentration
decrease.
Soil molybdenum
? Soils derived from quartzic material,sandy
pebbly(多卵石的 ) alluviums(冲积物 ),and
sandy loam and soils with high anion
exchange capacity are often Mo deficiet.
? Peat soils
? Calcareous soil derived from loess and
alluvium
Mo in physiology
? Content of Mo in plant
? The Mo concentration of plant materials
is usually low and plants are adequately
supplied with less than 1 mg/kg dry
matter,Deficiency is usually under 0.2
mg/kg dry matter,
Mo concentration in different plants in μg Mo/g
in the dry matter (Johnson 1966)
L u c e r n e l e a v e s 0, 3 4 S u g a r b e e t t o p s 0, 7 2
P h a s e o l u s b e a n t o p s 0, 4 0 T o m a t o l e a v e s,h e a l t h y 0, 6 8
S p i n a c h l e a v e s 1, 6 0 T o m a t o l e a v e s,d e f i c i e n c y 0, 1 3
Mo in physiology
? Mo uptake and translocation
? Mo is absorbed by plants as molybdate.
? The uptake is depressed by the SO4-
and phosphate.
? Mo may possibly move in xylem as MoO42-,
as Mo-S amino acid complex or as a
molybdate complex with sugar or polyhydroxy
compounds.
? Mo is moderately mobile in plant,
Mo function in plant
? Mo is an essential component of nitrate
reductase and nitrogenase
? Mo plays another essential role in the N
metabolism in legumes such as soybean and
cowpea.—xanthine dehydrogenase (黄嘌呤脱
氢酶）
? Other functions
? Synthesis of vitamins
? IAA oxidase activity
? Phosphatase activity
? Chlorophyll structure stability
Symptoms of Mo deficiency
? Mo deficiency frequently begins in the
middle and older leaves.
? Interveinal mottling,marginal chlorosis
of the older leaves and upward curling
of the leaf margins are all typical,
? As the deficiency progress necrotic
spots appear at leaf tips and margins.
Symptoms of Mo deficiency
? In the cruciferae the lamella is not properly
formed and in the extreme case only the leaf
rib is present,like a whip,so the deficiency is
called,whiptail”
? Curd(胚乳） formation is also distorted
? In Mo deficiency maize the tasseling stage(抽
穗期） is delayed; flower fail to open and
grain size and viability is greatly reduced;
premature sprouting（萌发） of grains.
Mo deficiency of cauliflower,interveinal mottling,marginal chlorosis
of the older leaves and upward curling of leaf margins and tip
necrosis in early stage； in the serious deficiency,leaf lamella is
not properly formed and in extreme case only the leaf rib is present,
it is called whiptail）； curd formation is also distorted.
?
TOMATO PLANTS Molybdenum deficiency
Leaflets somewhat chlorotic,strongly incurled and die
back from tips,
Left,healthy leaf receiving molybdenum,Right:
Molybdenum deficient leaf; leaflets,incurled margins,
intervenal chlorotic motting and death of tips.
?
?
? Young Cabbage
Plants (Savoy)
Molybdenum
deficiency
? Leaves cupped and
show chlorotic
mottling,especially
around margins; tips
and margins develop
dead patches; plants
fail to heart,(Similar
to manganese toxicity；
Mo toxicity
? High Mo levels in fodder and a Mo concentration
of 5 to 10 mg Mo/kg in the dry matter is
dangerous to ruminants such as cattle,
? Molybdenosis (慢性钼中毒 ),diarrhoea（腹泻）,
depigmentation (褪色 ) of hair or wool,bone
formation and reduction in growth.
? Poorly drained soils derived from granitic (花岗岩）
alluvium and black shales ash on highly organic
soils.
Mo fertilizers
? Molybdenum trioxide MoO3 Mo 60%
? Ammonium
molybdate(NH4)6Mo7O24.4H2O
? Mo 54%
? Na molybdate Na2MoO4.2H2O Mo 38-
46%
? Molybdenized superphosphate
Application of Mo fertilizers
? Seed treat
? ７ g/ ha
? Soil apllication
? 0.01-0.5kg/ha
? Foliage spray
? 85g/ha
