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Soils and Mineral Nutrition - Coggle Diagram
Soils and Mineral Nutrition
Essential Elements
hydroponic solution
chemical composition carefully controlled
Julius von Sachs 1860
supports plant growth
necessary vs toxic chemicals
if positive growth
composition is made identical minus 1 ingredient
if not essential plants grow normally
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Criteria for Essentiality
1.
element must be necessary for complete normal plant development through full life cycle
differentiation, reproduction, or survival
essential
hydroponic solution must be protected carefully from dirt, dust, etc.
cannot study large trees in greenhouses
practical assumptions are made
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2.
element itself must be necessary and
no substitute can be effective
relatively straight-forward
if essential element is absent
chemically related elements does not keep plant alive
some can be substituted in specific enzymatic reactions
3.
element must be acting within the plant, not outside it
complexity of test solubility makes it difficult to analyze results
Soils and Mineral Availability
soil derived through weathering
rock not suitable because of crystal matrix
physical vs chemical weathering
physical weathering breaks down rocks by physical forces
wind, water movement, temperature changes
runoff, avalanches, rock fragmentation
corse-sand
size range 2.0-0.2 mm
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chemical weathering decreases soil particle size
matrix elements become available to plants
cations are released
attraction is beneficial
Cation Exchange
loosely bound to micelle surfaces
due to their charge, roots cannot absorb directly
cation exchange
presence of proteins acidifies soils
waste does not hurt plant
exported upward through xylen
decaying organic matter releases - charged matrixes
Soil Acidity
concentration of free protons in soil solution
important for cation exchange and cation retention
during heavy rain
as acidity increases more cations are released from soil micelles
too many or too few protons in soil based on pH
changes solubility
chemical nature of the original rock
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Endodermis and Selective Absorption of Substances
enter roots by crossing plasma membrane and entering the simplistic protoplasm phase of the plant
or by diffusing in cell walls and intracellular spaces in the apoplastic phase
selective permeability
can penetrate simply by moving with water through plant
any substance can enter, harmful or not
impermeable Casparian strips prevent water
Mycorrhizae and the Absorption of Phosphorus
90% of roots form symbiotic association with soil fungi
called mycorrhiza
allows plants to absorb phosphorus
Mineral Deficiency Diseases
Causes of Deficiency Diseases
all types of soil contain small amounts of all essential elements
uncommon to find plants suffering from overabundance
some extra minerals can be precipitated as crystals
desert soils
excessive amounts of all available minerals because groundwater moves upward
can grow too strong from too high concentration of minerals
bad for trees
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Symptoms of Deficiency Disease
closely related to particular lacking element
all plants suffer from scarcity of particular essential element
chlorosis
leaves lack chlorophyll
yellowish, brittle, and papery
deficiencies of nitrogen or phosphorus
cause accumulation of anthocyanin pigments
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Mobile and Immobile Elements
important diagnostic technique
whether symptoms appear in young leaves or older leaves
immobile elements
boron, calcium, iron
after they have been incorporated into plant tissue they do not move
growth is normal until soil is exhausted
mobile elements
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Nitrogen Metabolism
nitrogen metabolism
Nitrogen fixation
nitrogen reduction
nitrogen assimilation
Nitrogen Fixation
conversion of N2 gas into nitrate, nitrite, or ammonium
human manufacturing
fertilizer
natural process fix over 190 million tons of nitrogen annually
lightening is important
nitrogen-fixing bacteria and cyanobacteria
convert 130 million tons of nitrogen to forms that plants and animals can use
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Nitrogen Reduction
process of reducing nitrogen in the nitrate ion NO3-
nitrogenase automatically reduces nitrogen
requires 8 electrons
becomes oxidized and must pick up more electrons
adds 6 electrons to nitrite reducing it to ammonium
Nitrogen Assimilation
actual incorporation of ammonium into organic molecules
similar to electron transport chain
acceptor molecule is glutamate
amino group
glutamine transfers ammonium
bases for incorporating nitrogen into the plant's metabolism and synthesizing all of the amino acids, nucleotides, chlorophyll, etc
transamination
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Other Aspects of Prokaryotes and Nitrogen
some bacteria oxidize nitrogen
adversely affects plants
nitrifying bacteria
oxidize ammonium to nitrate and others oxidize nitrate to nitrate
nitrification
important ecological consequences
large amounts of ATP must be reduced
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Obtaining Nitrogen from Animals
soils in bogs and swamps have little nitrogen available
carnivorous plants
numerous mechanisms because it has developed separately in different plants
Ant-plants
flowering plants and ferns obtain reduced nitrogen from animals
epiphytic
mutualistic
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Plants Eat Dirt; Animals Eat Protoplasm
at fundamental level level plant and animal nutrition is almost identical
same amino acids, nucleic acids, and sugars
as similar as they are very different
plants make everything organic in their bodies
balanced diet is dirt
photosynthesis
animals lack synthetic pathways
must obtain nutrients through diet
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Acid Rain
silent killer
destroying forests, streams, and lakes
as we burn fuels
sulfur dioxide reacts with water to form sulfuric acid
acid rain
precipitation carries sulfuric acid down
damages plants
some acid moves inside plants
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Plants and People
From Fertility gods to Fertilizers
field mineral nutrition excellent for studying the development of biological thought
farming for thousands of years
earliest thoughts about plant growth came from the Greeks
"plants do not grow unless their roots are in earth"
unchanged until 1600s
J.B. van Helmont
cutting willow experiment
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Fertilizers, Pollution, and Limiting Factors
plants in nature don't grow vigorously
desert plants grow faster with more water
given more fertilizer or nitrogen won't change growth rate
limiting factor
difficult to stop pollution
Storage of Minerals Within Plants
cannot be certain that essential minerals will be available
animals have large reservoirs of some elements
muscle protein can be broken down into amino acids
amino group
plants rarely store minerals or nitrogen as crystals
flower buds and maturation
all parts of plants except seeds store minerals in soluble form in central vacuoles
does not permit storage of large amounts of miners
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