plant mineral nutrition - wordpress.com · 2015-03-06 · plant mineral nutrition . main driving...

Plant Mineral Nutrition

Main driving forces for

water flow from the

soil through the plant to the

atmosphere

• Differences in water vapor

concentration,

• Hydrostatic pressure,

• Water potential .

Root hairs

make

intimate

contact

with soil

particles

WATER ABSORPTION BY

ROOTS

Animation

Mineral Nutrients

MINERAL NUTRIENTS ARE ELEMENTS

acquired primarily in the form of inorganic ions from the soil.

The study of how plants obtain and use mineral nutrients is

called mineral nutrition.

Mineral Nutrition

Growth Factors:

What do plants need to grow?

1.

2.

3.

4.

5.

6.

What is an essential plant nutrient?

The criteria for essentiality: Arnon and Stout, 1939

All the nutrients needed to carry out growth and

reproductive success; full life cycle

2. The element cannot be replaced or substituted

1. Omission of the element will result in abnormal growth

3. The element must exert its effect directly on growth


There are 17 known (accepted) elements that are

essential for plant growth

Hydrogen, Oxygen, Carbon – plant gets from air

and water

The other 14 are mineralized elements derived from

soil (or air as in N)

Other nutrients being studied:

Silicon, Cobalt, Aluminum

Types of Nutrients • 1. The first group of essential elements forms the organic (carbon)

compounds of the plant. Plants assimilate these nutrients via

biochemical reactions involving oxidation and reduction.

• 2. The second group is important in energy storage reactions or in

maintaining structural integrity.

• 3. The third group is present in plant tissue as either free ions or

ions bound to substances such as the pectic acids present in the

plant cell wall.

• 4. The fourth group has important roles in reactions involving

electron transfer.

Relationship between plant growth

and nutrient concentration

• What happens when a nutrient or nutrients

are inadequate in supply?

• Can the concentration of a nutrient be too

high?

Plant growth progresses to

the limit imposed by the

nutrient in least supply


Techniques Are Used in Nutritional Studies

Absence or excess of any

nutrient….. Hoagland

solution

1)Hydroponics

2) Nutrient film growth

system

3) Aeroponic growth system

Mineral Deficiencies Disrupt Plant Metabolism

and Function

• Both chronic and acute deficiencies of several

elements may occur simultaneously.

• Deficiencies or excessive amounts of one element

may induce deficiencies or excessive accumulations

of another.

• Some virus-induced plant diseases may produce

symptoms similar to those of nutrient deficiencies.

Forms in which nutrients exist

• cation – positively charged ion

• anion – negatively charged ion

• neutral – uncharged

• Plants used the mineralized from of a nutrient – It does not matter to the plant where it comes from

So which nutrients exist in what form?

• ammonium – NH4+

• potassium – K+

• calcium – Ca+2

• magnesium – Mg+2

• iron – Fe+2, Fe+3

• zinc - Zn+2

• manganese Mn+2, Mn+4

• copper – Cu+2

• cobalt – Co+2

• nickel – Ni +2

• nitrate – NO3-

• phosphate – H2PO4- , HPO4

-2

• sulfate - SO4-2

• chlorine – Cl-

• borate - H3BO3, H2BO3-, B4O7

-2

• molybdate – MoO4-2

Anions Cations

Factors that affect nutrient uptake

• Getting nutrients to the plant roots

– Nutrients are water soluble

• What factors affect nutrient availability

– pH

– Cation Exchange Capacity

• Colloids (humus, clay)

Getting nutrients to the roots: Mechanisms for nutrient delivery

• mass flow

– the passive movement of nutrients in soil water

to roots

• diffusion

– the movement of nutrient from regions of high

concentration to regions of low concentration

• root interception

– direct contact of nutrients with roots as roots

grow and explore soil

Getting nutrient to the roots:

Mechanisms for nutrient

delivery

Properties Affecting Nutrient Availability

p = potential or power

H = hydrogen

Chemical Properties - pH

• pH and hydrogen ion

concentration are inversely

related.

• As pH increases, hydrogen

ion concentration

decreases.


• Logarithmic scale

pH of 6

has 10x more H+

than pH 7

pH [H+] [H+]

1 10-1 .1

2 10-2 .01

3 10-3 .001

4 10-4 .0001

5 10-5 .00001

6 10-6 .000001

7 10-7 .0000001

8 10-8 .00000001

9 10-9 .000000001



pH affects the availability of nutrients


Chemical Properties – Cation Exchange Capacity C E C

• ammonium – NH4+

• potassium – K+

• calcium – Ca+2

• magnesium – Mg+2

• iron – Fe+2, Fe+3

• zinc - Zn+2

• manganese Mn+2, Mn+4

• copper – Cu+2

• cobalt – Co+2

• nickel – Ni+2

• nitrate – NO3-

• phosphate – H2PO4-HPO4

-2

• sulfate - SO4-2

• chlorine – Cl-

• borate - H3BO3, H2BO3-, B4O7

-2

• molybdate – MoO4-2

Cations Anions


Growing Media - Chemical Properties


OH-

OH-

OH-

OH-

H+ H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+ H+

H+ H+

H+

H+

H+

H+

H+ H+

H+

H+

H+

H+ H+

H+

OH-


Negatively charged chemical groups OH- on humic particles

Sometimes associated with Fe and Al in clays

pH

High or Low ?

Low




H+

H+

H+

H+ H+

H+

H+

OH-

OH-

OH-

OH-

OH-

Negatively charged chemical groups OH- on humic particles

Sometimes associated with Fe and Al in clays

pH

High or Low ?

High


The ability of a soil or substrate to provide a nutrient reserve

It is all the exchangeable cations the soil or substrate can adsorb

The CEC of a soil depends on colloids and pH


The higher the CEC of a soil the better buffering capacity

attracts

Chemical Properties – Colloids and CEC

Colloids - very small particles in soil that are

chemically reactive (charged) – humus, clay

K+ Fe++

Mg++

Mn++

H+

Fe++

Mg++

Mg++

Mn++

H+

H+

Ca++

K+

+




Chemical Properties - Colloids and CEC

OH-

OH-

OH-

OH-

OH-

Example of one scneario:

some nutrients become more available at low pH

Mn++

Mn++

Mg++

Mn++

Mn++ Mg++

Ca++

Fe++

Fe++

Fe++

Fe++

Fe++



Chemical Properties – CEC

OH-

OH-

OH-

OH-

OH-

H+ ions vie for space, certain ions released becoming available

Mn++

Mn++

Mn++

Mn++

Mn++

Mn++

Ca++

Fe++

Fe++

Ca++

Fe++

Fe++

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+ H+

H+ H+

H+

H+ H+

H+

H+

H+

H+

H+

pH ≈ 5.8


The ability of a soil or substrate to provide a nutrient reserve

Types of Soil Colloids Cation Exchange Capacity

(cmolc/kg of colloid)

humus 100-300

vermiculite 120-150

montmorillonite 60-120

illite 15-40

0-3* iron oxides


10 – 10 – 10

What’s on the Bag

N P K

# - # - #

N

1.00

N

0.44 0.83 –

–

–

– P K

– P2O5 – K2O

The Major Players – N and P

• Nitrogen

– NO3- N and NH4

+-N or urea

• Phosphorus

– H2PO4--P at pH of 5.0 to 6.5

Nitrogen (N)

– NO3- N and NH4

+-N or urea

utilized for a variety of structural and metabolic compounds

over half of N in plants is found in the leaves of plants

between 15 and 30% of that leaf nitrogen goes into the production

of Ribulose 1-5-biphosphate carboxylase or Rubisco

Nitrogen is very mobile within the plant

NO3- nitrate

Nitrogen (N)

taken up by plants passively and actively

uptake increases pH in soil

best uptake pH range between 4.5 and 6

nitrate can be stored in plant

nitrates leach

taken up by plants passively and actively

decreases pH in soil

ammonium (ammonia) cannot be stored

must be assimilated immediately by carbon

NH4+ ammonium

ericaceous species utilize

Nitrogen (N)

Phosphorus (P)

H2PO4- -P at pH of 5.0 to 6.5

High pH, P binds with calcium

Low pH P, binds with iron

High P fertilizers do not promote root growth

Utilized for energy transfer, membrane structure, nucleic acids,

proteins

Mobile in plant

Nutrient Interactions: Relationships of elemental excess

in growing media to potential nutrient deficiencies in plant tissue.

Element in excess in media Element possibly deficient in plant tissue

Nitrogen as ammonium Potassium, Calcium, Magnesium

Potassium Nitrogen, Calcium, Magnesium

Phosphorus Copper, Zinc, Iron

Calcium Magnesium, Boron

Magnesium Calcium, Potassium

Sodium Potassium, Calcium, Magnesium

Manganese Iron, Molybdenum

Iron Manganese

Zinc Manganese, Iron

Copper Manganese, Iron, Molybdenum

Molybdenum Copper

Aluminum: this element is not essential and high levels are rare in artificial soils. High Aluminum will precipitate Phosphorus as Aluminum Phosphate and can highly reduce short term Phosphorus availability.

Mobility of Plant Nutrients: Mobility of elements in the

plant often defines the location of visual symptoms of nutrient deficiencies or toxicities:

Very Mobile

Moderately Mobile

Limited Mobility

Nitrogen Magnesium Iron

Phosphorus Sulfur Manganese

Potassium Molybdenum Copper

Chlorine Zinc

Calcium

Boron

* Most recently matured leaves are the most accurate leaf sample for nutrient analysis.

Nutrient Form:

Organic or Inorganic?

• Plants used the mineralized form of a nutrient

– It does not matter to the plant where the nutrient comes from,

as all nutrients taken up are in a mineralized form

– See handout on types of organic and inorganic fertilizers

• However adding composted organic matter to your soil

will aid in nutrient availability

– See lesson on soils

Nutrient Form:

Composts and Teas?

• Composts are denatured organic materials

– A true aerobic compost requires 3 things

• Aeration

• Moisture – 40 to 60 %

• A C:N ratio of 30 to 1

• Anaerobic composting – less heat, more break down,

increased humus production, but more noxious gases

• Making teas from composts is easy, however

making a consistent product is not

– Anti-pathogen properties

Foliar Nutrient Application

• Plants use the mineralized form of a nutrient – The majority of nutrient uptake are via plant roots

– Nutrients can be applied via foliar application

– Foliar application should merely be supplemental

• For most nutrients

– If foliar application is the primary method of nutrition

something is wrong with your soil ! (or roots)

Other Negative Effects of Nutrient Over-application

• Runoff

• Physiological responses

may affect root growth

e.g. recent evidence shows P does not promote root growth

may affect flowering

e.g. over application of N and other nutrients may

stimulate vegetative growth as in grapes

• Inappropriate fertilizers

NO3 is not well utilized by ericaceous species

• Balance your NO3 with your NH4

good for most plants

Timing of Fertility

• Evidence of periodicity in nutrient uptake in some species

• evidence for opposite shoot growth/root uptake periods

• fall uptake for spring growth

• Arborist stress fall fertilization of trees and shrubs

• Some concern over cold hardiness issues with fall N fertility

• Lawn care specialists suggest fall fertilization

• Tree nursery recommendations stress split fertilization

early spring and mid summer

Nitrogen (N)

Deficiency

- occurs in oldest leaves first

- stunted growth yellowing, chlorosis, stunted growth,

leaf drop, increased root shoot ratio

Symptoms of Deficiency and Toxicity

Toxicity

- occurs with ammonium only

- yellowing, chlorosis, root death

- interactions with K, Ca, Mg

Phosphorus (P)

Deficiency


- older leaves darken and turn purple, leaf margin necrosis,

low production of flowers, fruit and seed


Toxicity

- mostly interactions with other nutrients including

zinc, copper and iron

Potassium (K)

K+

Like phosphorus, potassium exists as many forms in soils, and

much of it is unavailable to plants,

Plants take up potassium in large amounts compared to other

nutrients. Only the demand for nitrogen is greater. In plant

tissue the N:K ratio is close to 1:1.

Maintains a variety of plant metabolic activity mainly by

regulating water status and stomatal control.

Aides in carbohydrate transport and cellulose production.

Mobile in plant

Potassium (K)

Deficiency


- yellowing of margins and tips of leaves

- edge “scorch”


Toxicity


calcium and magnesium

Sulfer (S)

SO4-2

In soil, the majority of sulfur is found in organic form and to a

lesser extent mineral form as sulfates

Plant roots actively take up sulfur primarily as sulfates SO4 -2,

Plants utilize sulfur in amino acids, proteins, vitamins and other

plant compounds like glycoside oils that give onions and mustards

their characteristic flavors..

Sulfur also activates certain enzyme systems

Not Mobile in plant

Sulfur (S)

Deficiency

- occurs in youngest leaves first

- similar to N deficiency


Toxicity

- There are rarely issues of toxicity

Calcium (Ca)

Ca 2+

Free calcium is loosely bound to organic and mineral colloids

Calcium is taken up passively in roots tips and moves

through the plant primarily via the xylem during

evapotranspiration

Mainly found in the cell walls

Not Mobile in plant

Responsible for membrane stability and cell wall integrity

Calcium is required for the extension of cell walls during cell

growth at shoot and root tips and enhances pollen tube growth.

Calcium (Ca)

Deficiency

- Occurs in youngest leaves first

- Reduction of growth at meristems

- Deformed and chlorotic leaves

- leag margin necrosis


Toxicity


magnesium, potassium causing deficiencies

Mg 2+

Magnesium is made available to the plant through exchange

with soil colloid complexes

Plants take-up magnesium passively, transported mainly through

the phloem

Fifteen to twenty percent of the magnesium in plants is found in

the pigment molecule, chlorophyll.

Mobile in plant

Cofactor for enzymes that help transfer energy and CO2 fixation

Magnesium (Mg)

Assists in RNA translation for protein synthesis

Magnesium (Mg)

Deficiency

- Deficiency symptoms appear in older leaves as interveinal

chlorosis.


Toxicity

- There is typically no magnesium toxicity.

Cl -

Chlorine naturally occurs in soils as constituents of many soil

minerals and is made available through natural weathering.

Taken actively and passively depending on soil concentrations,

active when low and passive when concentrations are high

Utilized in several processes of photosynthesis.

Mobile in plant

Chlorine (Cl)

Chlorine (Cl)

Deficiency

- Deficiencies are uncommon


Toxicity

Yellowing and burning of leaf tips, with interveinal areas

being bleached, scorched and necrotic in severe cases.

Fe 2+

Iron is ubiquitous in many soils, yet availability depends on

soil chemistry.

Actively taken up by the plant and is transported by xylem

to the leaves.

Utilized in several processes of photosynthesis.

Not mobile in plant

Iron (Fe)

Deficiency

- Iron deficiency is similar to magnesium deficiency

symptoms (interveinal chlorosis), but occurs on youngest

leaves first


Toxicity

- iron interferes with manganese uptake manganese

deficiency (mottled yellowing between veins developing

as necrotic lesions later), as.

Iron (Fe)

Mn 2+

Availability depends on pH and organic colloid content.

Increased in low pH

In the plant manganese is transported in the xylem and delivered

to mertistematic tissue where it is largely immobilized.

Cofactor for many metabolic enzymes and is important factor

in photosynthesis. Used to split water.

Not mobile in plant

Manganese (Mn)

Deficiency

- Interveinal chlorosis, similar to iron and zinc.


Toxicity

- Toxicity varies among species.

- Occurs in acid soil conditions when manganese is most

available

- Dark purple or brown spots within the leaf margins and/or

leaf tip necrosis

- Toxicity varies among species. Plants associated with acid

soils are naturally tolerant to high manganese conc.

- Severe toxicity results in stunted and yellowed meristems.

Manganese (Mn)

H3BO3

Availability depends on pH and organic colloid content.

Increased in low pH

Boron moves into the plant, passively taken up in solution by the

roots via evapotranspiration, moving through xylem

Factor in cell growth, including division, differentiation, and

elongation

Not mobile in plant

Boron (B)

Cell processes like carbohydrate metabolism and other

metabolic pathways

Concentrated at growth areas including reproductive structures.

Deficiency

- Since boron is associated with cell growth, deficiencies

usually show up in new growth as wrinkled and withered

leaves, with tip death soon after.

- Like calcium, deficiencies may be caused by drought or

high humidity.


Toxicity

- Toxicity can develop quickly, the range between deficient

and toxic supply is small.

- Different tolerances among plant species.

- Yellowing of the leaf tips, interveinal chlorosis and leaf

margin scorching.

Boron (B)

Cu 2+

Optimally available in slightly acid conditions where the copper

ion exchanges with other cations on soil colloids

Root uptake is active and copper moves in the xylem, complexed

with amino acids and other nitrogenous compounds.

Copper is utilized with enzymes for metabolic activities and

photosynthesis.

Not mobile in plant

Copper (Cu)

Deficiency

- Deficiencies of copper show up on the youngest leaves

first

- Depressed and twisted growth

- New leaves appear pale along the margins but green at the

end of the veins.

- Spotty necrosis occurs in the leaf margins. Stems may

become distorted and twisted.


Toxicity

- Toxic levels of cooper induce iron deficiency and

accompanying symptoms along with depressed root

growth.

Copper (Cu)

MoO4 -2

Molydenum uptake is dependent on solubility of the ion. Unlike

many micronutrients, molybdenum becomes more available in

higher pH.

In the leaf, used for an important enzymatic process called nitrate

reduction, the first of two important physiological steps that

make nitrate usable in the plant

Relatively mobile in plant

Molybdenum (Mo)

Deficiency

- Since molybdenum is essential for nitrate reduction, a

deficiency in molybdenum manifests as a nitrogen

deficiency

- leaf chlorosis in older leaves

- then leaf margin wilting

- leaf and meristem death


Toxicity

- rare in soils and plants can tolerate relatively high levels of

molybdenum

Molybdenum (Mo)

Zn +2

Slightly mobile in plant, mainly stored in roots

Zinc (Zn)

present in sulfide and silicate minerals and is also associated

with organic colloids

Zinc is actively taken up by plants and transported through the

xylem metabolic functions including auxin (growth hormone)

production, a cofactor in protein synthesis, enzyme activity and

carbohydrate metabolism and regulation.

chlorophyll production

may enable plants to tolerate colder temperatures

Deficiency

- Symptoms on older leaves first

- Include interveinal chlorosis, curled and dwarfed leaves

and then leaf scorch and necrosis.

- excessive phosphorus can interfere with zinc uptake


Toxicity

- May occur in low pH soils (< pH 5) or where municipal

sludge has been added to soils

- Toxicity concentrations are species dependent

- interfere with iron uptake

Zinc (Zn)

Ni +2

Possibly mobile in plants

Nickel (Ni)

Nickel is the newest recognized essential plant nutrient

requirement was not known because impurities in

irrigation water and fertilizers supplied the very low

requirements of this nutrient

required for the enzyme urease to metabolize urea, releasing

the ammoniacal nitrogen for plant use

for iron absorption and seeds production and germination

evidence to suggest that carbon respiration and nitrogen

metabolism are sensitive to Ni nutrition

Deficiency

- rounded, blunt and slightly curled leaves known as

“mouse-ear”

- seen on spring growth and is a result of accumulation of

urea to the point of toxicity


Toxicity

- At a level of 100 ppm or higher, nickel is considered to be

phytotoxic

- toxicities typically exist in areas where industrial waste has

been concentrate

- In beets severely stunted growth; young leaves at early

stage show chlorotic iron deficiency symptoms, followed

by severe necrosis, collapse and death

Nickel (Ni)

Analysis of Plant Tissues Reveals

Mineral Deficiencies

• Soil analysis vs plant tissue analysis

Add new methods?

TREATING NUTRITIONAL

DEFICIENCIES • Crop Yields Can Be Improved by addition of

Fertilizers

• Soil pH Affects Nutrient Availability, Soil

Microbes, and Root Growth

• Different Areas of the Root Absorb Different

Mineral Ions

• Mycorrhizal Fungi Facilitate Nutrient uptake

by Roots

• Excess Minerals in the Soil Limit Plant

Growth

Discussion Paper

• For Next WEEK

Plant Cell Physiol. 2014 Dec;55(12):2027-36. doi: 10.1093/pcp/pcu156. Epub 2014 Nov 6.

Strategies for optimization of mineral nutrient transport in plants:

multilevel regulation of nutrient-dependent dynamics of root

architecture and transporter activity. Aibara I1, Miwa K2.

Abstract

How do sessile plants cope with irregularities in soil nutrient availability? The uptake of essential

minerals from the soil influences plant growth and development. However, most environments do

not provide sufficient nutrients; rather nutrient distribution in the soil can be uneven and change

temporally according to environmental factors. To maintain mineral nutrient homeostasis in their

tissues, plants have evolved sophisticated systems for coping with spatial and temporal variability

in soil nutrient concentrations. Among these are mechanisms for modulating root system

architecture in response to nutrient availability. This review discusses recent advances in

knowledge of the two important strategies for optimizing nutrient uptake and translocation in

plants: root architecture modification and transporter expression control in response to nutrient

availability. Recent studies have determined (i) nutrient-specific root patterns; (ii) their

physiological consequences; and (iii) the molecular mechanisms underlying these modulation

systems that operate to facilitate efficient nutrient acquisition. Another mechanism employed by

plants in nutrient-heterogeneous soils involves modification of nutrient transport activities in a

nutrient concentration-dependent manner. In recent years, considerable progress has been made

in characterizing the diverse functions of transporters for specific nutrients; it is now clear that

the expression and activities of nutrient transporters are finely regulated in multiple steps at both

the transcriptional and post-transcriptional levels for adaptation to a wide range of nutrient

conditions.

http://www.ncbi.nlm.nih.gov/pubmed/25378690

http://www.ncbi.nlm.nih.gov/pubmed/?term=Aibara%20I%5BAuthor%5D&cauthor=true&cauthor_uid=25378690

http://www.ncbi.nlm.nih.gov/pubmed/?term=Miwa%20K%5BAuthor%5D&cauthor=true&cauthor_uid=25378690

plant mineral nutrition - wordpress.com · 2015-03-06 · plant mineral nutrition . main driving...

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