Vascular cylinder

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Vascular cylinder
cortex
xylem
phloem
endodermis
pericycle
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Pathway of water movement

• The endodermis regulates what ions enter the
  vascular tissues

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Water movement

• Water movement into the tissues of the plant
  follows the water potential gradient

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Absorption lag

• Caused by resistance in the water path in the
  root (water must pass through endodermis)
• Roots cut off under water in an actively
  transpiring plant increases xylem absorption.
• Lag can cause mid-day closure of stomata until
  absorption rate catches up

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Root pressure

• Minerals actively pumped into the xylem lower
  water concentration
• Water diffuses into the xylem causing a pressure
  to build since the cells can not expand
• Water is forced up the xylem

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Leaf guttation

• Root pressure can cause guttation of water from
  the leaf, especially in small plants

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Nutrients

• Negative charges are found on clay and humus
  particles and to a lesser extent on silt
  particles
• Ions (K,Ca, Mg, etc.) are attracted to the
  negative charges and therefore next to the
  particle.

K
Ca
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Cation Exchange

• Mineral element - sand, silt and clay
• Reverse of Coloumbs law because of hydration
• F k (ea eb)/d2 d rarb e
  charge r radius of particle
• HgtCagtMggtKgtNa
• Oscillations (brownian movement) and the exchange
  process
• H is the best for exchange, since it is held the
  tightest. The is the ion that plants give off
  (from COOH)
• Contact exchange - with pectic substances

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Epidermal cells - root hairs

• H ions released to the soil solution exchange
  with other ions near soil particles

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Humus Content

• Also holds cations
• higher capacity than clay
• COOH groups on surfaces
• Can aid in liberating elements from mineral bases
  
• puts K in an exchangeable form
• Friability of the soil
• N content

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Plant Nutrients

• Macronutrients
• C H O N P K Mg Ca S
• Micronutrients
• Fe, Mn, B, Cu, Zn, Cl, Mo
• C H O P K N S CaFe Mg B Mn CuZn Cl Mo
• C H O come from the atmosphere as does S in
  some cases.
• Others are from soil solution

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Availability and Growth
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Nitrogen

• Necessary part of proteins, enzymes and metabolic
  processes involved in the synthesis and transfer
  of energy.
• Part of chlorophyll
• Helps with rapid growth, increasing seed and
  fruit production
• Improves the quality of leaf and forage crops. 
• Comes from decomposition, fertilizer application,
  and from the air
• (legumes get their N from the atmosphere, water
  or rainfall contributes very little nitrogen)

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Phosphorus

• Essential part of photosynthesis process. 
• Involved in the formation of all oils, sugars,
  starches, etc.
• Helps with proper plant maturation withstanding
  stress.
• Effects rapid growth.
• Encourages blooming and root growth.
• Comes from fertilizer, bone meal, and
  superphosphate. 

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Phosphorus Availability
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Potassium

• Absorbed by plants in larger amounts than any
  other mineral element except nitrogen and, in
  some cases, calcium. 
• Building of protein, photosynthesis, starch
  formation, fruit quality and reduction of
  diseases.
• Osmosis, stomatal opening, ionic balance
• Not part of plant structure
• Supplied to plants by soil minerals, organic
  materials, and fertilizer.

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Potassium Availability
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Calcium

• An essential part of plant cell wall structure,
  thus for growth.
• Affects membrane permeability
• Provides for normal transport and retention of
  other elements as well as strength in the plant.
   
• Sources are dolomitic lime, gypsum, and
  superphosphate.

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Magnesium

• Part of chlorophyll molecule
• Helps activate many plant enzymes needed for
  growth.
• Soil minerals, organic material, fertilizers, and
  dolomitic limestone are sources

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Sulfur

• Essential for production of protein.
• Promotes activity and development of enzymes and
  vitamins.
• Helps in chlorophyll formation.
• Improves root growth and seed production.
• Helps with vigorous plant growth and resistance
  to cold.
• Supplied to soil from rainwater. It is also added
  in some fertilizers as an impurity, especially
  the lower grade fertilizers. The use of gypsum
  also increases soil sulfur levels. 

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Micronutrients

• Mostly involved as parts of enzymes
• Many are involved in photosynthesis and
  respiration
• Boron affects membrane transport and Ca use

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Nutrient Deficiencies

• Deficiency is determined by function of nutrient
• Location is determined by mobility of nutrient
• Easily mobile nutrients, such as magnesium, move
  through phloem source-to-sink translocation to
  younger tissues
• older tissues demonstrate deficiency first
• Relatively immobile nutrients, such as iron, do
  not move
• younger tissues demonstrate deficiency first

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Nitrogen Deficiency

• Light green to yellow appearance of leaves
• Older leaves first
• Reddening in severe cases
• Stunted growth
• Poor fruit development

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Supply can make a difference!
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Phosphorus Deficiency

• Dark green foliage turning to reddish in portions
• Fruit and seed yield reduced or stopped
• Drought, disease, and insect susceptibility

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Potassium Deficiency

• Older leaves yellow initially around margins and
  die
• Irregular fruit development
• Variability depending on crop

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Sulfur Deficiency

• Yellowing of leaves
• Occurs on young leaves first
• Sometimes vein area are lighter green than area
  between veins

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Magnesium Deficiency

• Yellowing between leaf veins
• Older leaves first
• Poor fruit development and production

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Iron Deficiency

• Yellowing between veins
• Young leaves first
• Eventually spots of dead tissue

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Calcium Deficiency

• Reduced growth
• Death of growing tips
• Blossom-end rot of tomato
• Poor fruit development and production

Cucumber
Lettuce
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Nutrient deficiency symptoms
S
N
K
P
Ca
Micro
Fe
Mg

• Tomato plants grown hydroponically

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Organic vs. processed fertilizers

• Organic
• Little or no processing
• Low analysis
• Usually slow release
• Often unknown analysis
• Usually a source of OM
• Processed
• Industrial processing
• High analysis
• Usually fast release
• Known analysis
• No Organic matter

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Nutrient ratios

• The level of one nutrient affects the critical
  level of another.
• Abundance of one element can hinder the uptake of
  another
• Liebigs Law of the minimum
• There are problems with this concept

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Natural sources

• Organic
• Manure
• Wood ashes
• Bone meal
• Biosolids
• Blood meal
• Others
• Processed
• N - air
• P - minerals
• K - salts

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CarbonNitrogen (CN) ratio

• Ranges from lt 51 to gt 5001 in organic materials
  
• Low CN materials supply N to plants
• High CN materials tie up N by biological
  immobilization

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Biological Release (Mineralization)

• N content and CN ratio
• Degree of decomposition (stability)
• Examples of available N
• Poultry manure - 40-70
• Stable compost - 0 -10
• Humus - 1-4
• Sawdust - negative

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Organic Materials - N availability

• Low CN ratio rich in N
• Use in small amounts as a fertilizer.
• Example undiluted manure or biosolids
• Medium CN slow release of N
• Use in larger amounts to replenish soil organic
  matter.
• Example compost, leaf mulch
• High CN reduce available N levels in soil
  (immobilization).
• Use as mulch.
• Example sawdust, straw

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Soil Tests

• What a Soil Test Tells You
• Relative levels of nutrients in your soil
• Fertilizer recommendation
• Standard soil test P, K, Ca, Mg, B, pH, lime
• No good soil test exists for nitrogen requirement

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Taking a Sample

• Sample defined area
• Take 10 or more subsamples (0-6 deep)
• Dry and mix well
• Subsample mixture and fill sample bag

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N fixing nodules
Rhizobium nodules
Actinomycete on Alnus