Biology 172 Chapter 37 Plant Nutrition

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Biology 172Chapter 37Plant Nutrition
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Figure 37.1 The uptake of nutrients by a plant
an overview
Nutrient Uptake in Plants
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Figure 37.2 Using hydroponic culture to identify
essential nutrients
Determination of Nutrient Needs
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Table 37.1 Essential Nutrients in Plants
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Symtoms of Mineral DeficiencyNutrient Mobility

• Leaf Color - Chlorosis
• Non-mobile nutrients Chlorosis in New Growth
• Iron
• Mobile nutrients Chlorosis in Old growth
• Magnesium

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Fig. 37-7
Healthy
Phosphate-deficient
Potassium-deficient
Nitrogen-deficient
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Concept 37.3 Plant nutrition often involves
relationships with other organisms

• Plants and soil microbes have a mutualistic
  relationship
• Dead plants provide energy needed by
  soil-dwelling microorganisms
• Secretions from living roots support a wide
  variety of microbes in the near-root environment

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Soil Bacteria and Plant Nutrition

• The layer of soil bound to the plants roots is
  the rhizosphere
• The rhizosphere has high microbial activity
  because of sugars, amino acids, and organic acids
  secreted by roots

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Figure 37.6 The availability of soil water and
minerals
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Rhizobacteria

• Free-living rhizobacteria thrive in the
  rhizosphere, and some can enter roots
• Rhizobacteria can play several roles
• Produce hormones that stimulate plant growth
• Produce antibiotics that protect roots from
  disease
• Absorb toxic metals or make nutrients more
  available to roots
• Inoculation of seeds with rhizobacteria can
  increase crop yields

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Bacteria in the Nitrogen Cycle

• The nitrogen cycle transforms nitrogen and
  nitrogen-containing compounds to usable thingies
  for plants. Bacteria are responsible for this.

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Nitrogen A Special Nutrient

• Decomposition of Organic Matteer
• Nitrogen Fixation Nitrogen Fixing Bacteria
• Convert N2 to NH3
• Nitrogenase
• Ammonium Ion NH4
• Nitrate NO3- Produced in Soil by Nitrifying
  Bacteria That Oxidize Ammonium
• Plants Convert Nitrate to Ammonium
• Denitrifying Bacteria Bad Guys

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Nitrogen FixationSymbiotic Bacteria

• Symbiotic Nitrogen Fixation
• Rhizobium - Nitrogenase
• Bacteriods
• Legumes - Nodules
• Agricultural Applications
• Legumes Green Manure
• Other Nitrogen Fixers
• Some Tropical Grasses and Trees
• Actinomycetes
• Azolla, Anabaena, Rice

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Figure 37.9 The role of soil bacteria in the
nitrogen nutrition of plants (Layer 3)
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Mycorrhizae

• Fungus Root
• Increases Absorption of Water and Nutrients,
  Particularly Phosphorus
• Ectomycorrhizae 10 fungus on outside of root
  hairs.
• Increased water uptake in plants.
• Endomycorrhizae 85 fungus on inside of root
  hairs.
• Haustoria
• Arbuscules
• Agricultural Importance

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Fig. 37-12
Epidermis
Cortex
Mantle (fungal sheath)
100 µm
Endodermis
Fungal hyphae between cortical cells
Mantle (fungal sheath)
(colorized SEM)
(a) Ectomycorrhizae
10 µm
Cortex
Epidermis
Cortical cells
Endodermis
Fungal vesicle
Fungal hyphae
Casparian strip
Root hair
Arbuscules
Plasma membrane
(LM, stained specimen)
(b) Arbuscular mycorrhizae (endomycorrhizae)
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Epiphytes, Parasitic Plants, and Carnivorous
Plants

• Some plants have nutritional adaptations that use
  other organisms in nonmutualistic ways
• An epiphyte grows on another plant and obtains
  water and minerals from rain

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Parasitic Plants

• Mistletoe
• Dodder
• Indian Pipe

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Carnivorous Plants

• Grow in Bogs
• Acid Soils
• Deficient in Nitrogen and Phosphorus
• Produce Food by Photosynthesis
• Secure Nitrogen and Phosphorus From Prey