Nutrient Balance

Nutrient Balance

NRES 406/606Spring 2013

hernandez.leo@cabnr.unr.edu

The study of how plants absorb and assimilate inorganic compounds is called Mineral Nutrition and it is specially important in agriculture and environmental protection

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http://serc.carleton.edu/images/microbelife/topics/map_of_gulf_of_.jpg

• Higher plants are autotrophic organisms

http://www.sheppardsoftware.com/content/animals/kidscorner/images/foodchain/fullchain.gif

• Higher plants are autotrophic organisms– Synthesize organic components out of the inorganic

elements found in their surroundings

http://www.sheppardsoftware.com/content/animals/kidscorner/images/foodchain/fullchain.gif

• Most of the nutrients plants need are taken up by the roots directly from the soil solution

• Most of the nutrients plants need are taken up by the roots directly from the soil solution

http://www.savingwithshellie.com/wp-content/uploads/2011/01/Vitaminwater.jpg

C H O

• ~85% of plant dry matter is made of– C (Atmosphere)

– H– O

http://www.lenntech.com/images/Water%20molecule.jpg

http://spark.ucar.edu/sites/default/files/images/large_image_for_image_content/co2_molecule_720x400.gif

What are those inorganic elements?

• Are all these elements equally important for plants?

What are those inorganic elements?

What are those inorganic elements?

Essential Elements

Essential elements

• Those that have a clear physiological role.• If plants receive all of these plus water and

sunlight they will synthesize all the compounds needed.

• Based on the relative abundance in the plant…

• Macronutrients– >1%– N,K, Ca, P,S, Mg

• Micronutrients (Trace elements)– <1%

http://www.stewardcoaching.com/wordpress/wp-content/uploads/2012/01/quality_vs_quantity.jpg

• Nutrient concentration is not constant among different plant structures.

Why leaves?

• Nutrient concentrations in the soils ultimately determine the acquisition and concentration in plants.

• Some soils have high concentration of specific elements, like heavy metals.– Au, Ag, Ni, Al Hg

Accumulator plantIn some cases, plants growing in soils with high concentration of a

particular element can accumulate large concentration of that element

without apparent side effects.

Equisetum

• The atmosphere is the mayor source of N– Biotic dinitrogen fixation– Deposition

• Some cations may come from particulates traveling form other regions or from industrial pollution– Na (sea salt in coastal regions)– Fe & P from Africa

Nature

• Nutrient recycling is the major source of soluble nutrients

http://polaris.umuc.edu/~meaton/edtc620/omed/images/decomposition.jpg

• Nutrient recycling is the major source of soluble nutrients

http://polaris.umuc.edu/~meaton/edtc620/omed/images/decomposition.jpg

Microbial Activity

1 2 3 4 5 6 7 8

2. How the element is found in the soil 3. How does it change from 2 to 44. For that plants take up the element 5. How does the element exist w/in the8. Within the plant plant

1 2 3 4 5 6 7 8

• Most of N in soil is found organically bound

• Microbial activity is required to make it available fro plants

• Element that plants need the most• N deficiency rapidly affects plant growth

• chlorosis

http://hort.ufl.edu/database/images/nutdef/thy9529_M.jpg

P• Integral component of plant cell• Used in energy metabolism• Stunt growth and yellow foliage

S• S and N are constituents of many

proteins.• Deficiency symptoms are very similar to

those of N.http://pics.davesgarden.com/pics/2008/12/20/darius/c498d5.jpg

http://www.ipni.net/ppiweb/gseasia.nsf/$webindex/914E7F33D866E03848256E8900362252/$file/%23601%20legume%20lcp%20k%20def.jpg

K• Inorganic form• Found as free cation in plants (Osmotic

potential)• Activates many enzymes involved in

photosynthesis

Mg• Enzyme activation• Synthesis of DNA and RNA• Deficiency causes intervein chlorosisCa• Synthesis of cell wall• Cell Division (mitotic spindle)

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http://cleatordesigns.files.wordpress.com/2011/03/032409-hartman-rhodo-fe-deficiency-kaiser-h17-73.jpg

Fe• Component of enzymes involved in e- transport• Intervenous chlorosis

http://www.drt.com.tr/doctoferro/images/chelate.jpg

Why a chelate?

All micronutrients are found as inorganic compounds in the soil

• N, P. S, Fe and Mg are directly involved in metabolic activities

• Ca and K are inorganic ions but are biological active ( osmotic potential)

• Leaves are the most common place of nutrient accumulation within plants (vacuole)

• Except Cl, all other micronutrients are stored as organic forms

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Nutrient Uptake

1. Dissolved nutrients are taking in with water due to the continuous movement of water driven by transpiration

SPAC

2.Proton pump: H+ excreted out of cells affect the absorptivity of ions in the soil and release them into the soil solution.

http://extension.missouri.edu/explore/images/mg0004art04.jpg

By releasing H+ and HCO3- from the roots, plants promote ion exchange at the surface of clay particles. (Root Exudates)

Nutrient Uptake

Nutrient Uptake3. Weathering of the soil:

Roots can release compounds that lower the pH breaking down soil particulates.

http://it.pinellas.k12.fl.us/Teachers/madeirosa/images/48655D05E7824170A64E008894255590.gif

http://www.drt.com.tr/doctoferro/images/chelate.jpg

Nutrient Balance

Episode II

Nutrient uptake

– Passive• Following a gradient

– Active• Against a gradient

http://www.funtasti.com/pdata/t/l-31.jpg

Ion Uptake into the cell• Passive transport– Transport proteins• Channels

– (Selective) pores– Size and Density

• Carriers *– Substance being transported binds to the carrier– Conformational change– Dissociation

Ion Uptake into the cell

• Active transport– Energy depends on photosynthesis and respiration– ATP-ases function as proton pumps• Electrochemical gradient

– Present in plasmalemma and the tonoplast

Proton Pump

http://avonapbio.pbworks.com/f/electrogenic.jpg

H+ Pump

Electrochemical gradient

Uniports

Cotransporters

Uniports:

•Integral proteins•Charge Specific•In the tonoplast these could be ion-specific.•Low affinity

Cotransporters:

•Integral proteins•Active transport•Require H+ pump•High affinity•One way & Two ways

Cotransporters

Response to Nutrient Supply

• Michaelis-Menten• Uptake increase in response

to supply until a maximum value is achieved (Imax)

• Km: nutrient concentration at which

• Imax/2 is reached

http://depts.washington.edu/wmatkins/kinetics/mm1.gif

Km as a measure of Affinity

• Km is a measure of the capacity of the root to use nutrient at low concentrations.

• Km Affinity

• Km Affinity

H.A.S

L.A.S

H.A.S L.A.S