Nutrition and Transport

1
Nutrition and Transport
2
Nutrients

• 95 of plants dry weight is carbon, hydrogen,
  and oxygen (carbohydrates, CO2 and water)
• Minerals provide proteins and nucleic acids
• Essential nutrients had role, no substitute,
  and a deficiency results in death.
• Macro and micronutrients according to
  concentration
• Beneficial required or enhances growth

3
soil

• Mixture of mineral particles, decaying organic
  material, living organisms, air and water
• Humus decaying organic matter
• Mineral particles
• Sand largest sized particles, water drains
• Silt - intermediate
• Clay fine particles, not good drainage, -
  charge, can retain charged minerals.
• Loam equal portions of silt, clay and sand, good

4
Soil profile

• Vertical section of ground
• Horizons, parallel layers
• A uppermost, litter and humus
• B inorganic nutrients leached form A
• C weathered and shattered rock
• Soil erosion water and/or wind carry soil away
  to new location
• Loss of topsoil

5
Water and mineral uptake

• Casparian strip suberin and lignin border sides
  of root endodermal cells, force water to enter
  cells
• Root hairs allow water in at epidermal cells
• Minerals enter plants in ionic forms via
  electrochemical gradient with ATP pump
• Root nodules fix atmospheric nitrogen to NH4.
• Epiphytes air plants, roots can absorb water or
  in pockets at base of leaves.

6
Transport mechanisms

• Xylem
• Tracheids contain pits at ends that allow fluid
  to flow from cell to cell
• Vessel elements long, tubular, form hollow
  pipeline
• Phloem
• Sieve tube members -
• Companion cells provide proteins to sieve-tube
  members

7
Water transport

• Root pressure formed when water enters the
  root, usually at night
• Guttation drops of water are forced out of vein
  endings along edges of leaves
• Cohesion-tension model of xylem transport
• Tension is created from the loss of water out of
  the leaves (transpiration), draws water up from
  roots in vessels
• Cohesion water molecules cling together
• Adhesion water molecules cling to walls of
  vessel elements
• Continuous water column

8
Stomata

• Bordered by guard cells
• Potassium ions accumulate within guard cells,
  water follows, stomata open
• Turgor pressure is increased in guard cells
• Hydrogen ions accumulate outside guard cells
• Stoma close when turgor pressure decreases
• K decreased and water leaves guard cells

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Organic Nutrient Transport

• Girdling removing a strip of bark from around a
  tree
• Pressure Flow Model of Phloem Transport
• Source (photosynthesis production leaves) to
  Sink (growth areas) usually leaves to roots
• Sucrose is actively transported from leaves to
  area of need, water follows per osmosis
• Sugar is used for respiration, water exits via
  osmosis to xylem