Plants and Inorganic Nutrients

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Plants and Inorganic Nutrients

• Animals Heterotrophic
• Plants - Autotrophic

What is plant nutrition?
Organic nutrition photosynthesis Inorganic
nutrition mineral elements from soil
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How is mineral nutrition studied under controlled
conditions?
Ideal Concentration Of Elements For The
Vegetative Reproductive Stages Of Cucumber
Plants
Plants do not need soil to grow if they are
supplied with specific mineral nutrients

Elements  Vegetable State  Reproductive Stage 
N 251 ppm 225 ppm
P 70 ppm 60 ppm
K 220 ppm 280 ppm
Ca 200 ppm 140 ppm
Mg 60 ppm 60 ppm
Fe 20 ppm 20 ppm
Mn 2 ppm 2 ppm
B 1 ppm 1 ppm
Cu 0.1 ppm 0.1 ppm
Mo 0.2 ppm 0.2 ppm
Zn 1.0 ppm 1.0 ppm
Hoaglands Solution Note that the amounts
required will be higher than found in most soils.
Why?
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Hydroponics
Nutrient film technique aeroponics
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How is mineral nutrition studied in the field?
Nutrient addition experiments at Rothhamstead
Experimental Station Conclusions Nutrient
availability influences growth, species
abundance, competition and soil microbial
populations
Park Grass Experiment started in 1856 (shown in
1941) Variables pH, P, K, Mg, Na, nitrate-N,
ammonium-N and Silicon Fertilized plots have
fewer species (2-3) vs. unfertilized 50-60)
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What are the essential nutrients?
Essential nutrients are needed for a plant to
complete its life cycle and/or part of some
essential plant part or molecule 17
nutrients Macronutrients H, C, O, N, K, Ca,
Mg, P, S Micronutrients Cl, b, Fe, Mn, Zn, Cu,
Ni, Mo
Nitrogen deficiency in corn
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What are the roles of the essential nutrients?
Nitrogen 80 of atmosphere, but not in the form
available to plants Pathway of
absorption NO3-(nitrate) ? NH4(ammonia) ?amino
acids (proteins, nucleic acids, etc)
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What are the roles of the essential nutrients?
Phosphorous often most limiting element in
natural environment Why? 1. uptake from soil
based on pH lt6.8 readily taken up 6.8 7.2
less readily taken up gt7.2 not available to
plants 2. Organic phosphate must first be
converted to an organic form by soil microbes
before it can be taken up by the roots (some
plants secrete phosphatase into soil)
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What are the beneficial nutrients?
Sodium Desert plants (Atriplex vesicaria)
involved with C4 pathway Silicon Taken up from
soil 1-2 of dry weight of corn
16 dry weight of Equisetum arvense
(Scouring Rush) involved with
limiting fungal infections and preventing
lodging Cobalt legumes required by symbiotic
N2 fixing bacteria Selenium accumulates in arid
soils of western US toxic to most plants
accumulated by certain legumes (Astragalus
example of a Locoweed)
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Plant requirements for nutrients is defined in
terms of critical concentration
Critical concentration supply of nutrient
(measured in tissues) just below concentration
that gives maximum growth
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Plants exhibit either morphological or
biochemical deficiency symptoms
Mobile elements symptoms first seen in older
leaves Immobile elements - symptoms first seen in
younger leaves
Manganese - immobile
Nitrogen - mobile
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Roots, soil and nutrient uptake
Soil has two phases Liquid phase water or
soil solution, gases, microorganisms Solid phase
mineral particles derived from rock, plus
organic matter Soil solution is a very dilute
(1mM) solution of ions Roots take up nutrients
from soil solution that are replenished by
release from solid phase
From http//www.laspilitas.com/advanced/pictures/
roots.jpg
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Soil as a nutrient reservoir
Soil has both inorganic and organic
colloids Soil ? clay (lt0.002 mm particles),
silt (0.02-0.002), sand (0.2-0.02) Clay forms a
colloid (particles too small to settle out, too
large to go into solution (Tyndall
Effect) Colloidal humus-organic material that
has been degraded to a colloidal
dimension Nutrient contribution colloidal humus
gt colloidal clay (in good soil)
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How do soil colloids work?
Effectiveness of colloids depend on Surface
area more area, more nutrient ions can be
held Surface charge Clay kaolinite (mostly
negative charges from ionized aluminum and silica
at edge of particle) Colloidal carbon negative
charges because of exposed carboxyl and hydroxyl
groups
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How do ions get from the soil into the plant?
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Are all ions taken up by a plant equally?
Accumulation ratio Ci (conc. inside cell)/C0
(conc. outside cell)
Ion Co Ci Ci/Co
K 0.14 160 1142
Na 0.51 0.6 1.18
NO3- 0.13 38 292
SO4- 0.61 14 23
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How do ions get across root cell membranes?
Carriers selectivity with low transport
rates Ion channels high transport rates (ex.
K rates into guard cells)
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Root Microbe Interactions
Root bacteria interactions
Cluster or proteoid roots
Root cap mucilage
http//www.tau.ac.il/ecology/virtau/3-philip_nemo
y/image006.jpg
www.ffp.csiro.au/research/ mycorrhiza/root.html
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Root Microbe Interactions
Ectomycorrhizae on pine roots http//www.forestpes
ts.org/nursery/images/fnp0-7.jpg
Endomycorrhizae http//www.mun.ca/biology/singlet
on/Topic2012/37-14-Mycorrhizae.jpg
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Benefit of mycorrhizae