Plant Nutrition

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Chapter 37

• Plant Nutrition Soil

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Macronutrients Micronutrients

• Essential nutrients Nutrients that must be
  consumed, plants cannot make these nutrients
• Macronutrients Needed in large amounts
• Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorous,
  Sulfur, Potassium, Calcium, Magnesium
• Micronutrients Needed only in small amounts
• Iron, Manganese, Zinc, Copper

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Rhizo -

• Rhizosphere soil layer bound to the plants
  roots
• Rhizobacteria soil bacteria
• Some rhizobacteria are called plant-growth-promoti
  ng rhizobacteria (PGPR)
• Wanna guess what they do?
• They promote plant growth by
• Producing chemicals that stimulate growth
• Produce antibiotics to protect roots from
  infection
• Absorb toxic metals or make nutrients available
  for plants

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Rhizobacteria (Page 2)

• Plant benefits were discussed on prior slide
• Bacterial benefits since 20 of photosynthetic
  products go to the bacteria
• Hence, bacteria benefit from a healthy plant
  (roots) in the rhizosphere

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Rhizobium Bacteria

• Bacteria that fix atmospheric nitrogen supply
  it as ammonium
• Legumes have a ready source of nitrogen
• Symbioses with Rhizobium (Root living) bacteria
• Peas, soybeans, peanuts, and alfalfa
• Nodules swellings in the roots infected by
  rhizobium bacteria
• Bacteroids bacteria in vesicles in root cells
  in the nodules

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Mutualistic Relationship?

• Rhizobium bacteria provide nitrogen in a usable
  form
• Used to make amino acids for plant growth
• Plant provides photosynthetic products to the
  nodules via the vascular system

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Mycorrhizae

• Mutualistic relationship between plant roots and
  fungus
• Two types
• Ectomycorrhizae
• Mycelium forms a dense sheath over the root
  surface
• Hyphae extend from the root to the soil
  increase surface area for absorption of water
  minerals
• Hyphae do NOT penetrate root cells

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Mycorrhizae (Page 2)

• Endomycorrizae
• Also called arbuscular mycorrhizae (Thats a
  mouthful!)
• Most common type (85 of associations)
• Look like regular roots
• No dense mantle covering root surface
• Hyphae penetrate the cortex (Which tissue type?)

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Chapter 38

• Angiosperm Reproduction

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Angiosperm Reproduction

• Angiosperms have 3 unique features
• Flowers, Fruits, Double Fertilization
• Microsporangia
• Pollen sacs in the anther
• Diploid cells meiosis ? male gametophyte
  (pollen)
• Pollen has 2 haploid nuclei
• Tube nucleus 1 sperm develops into a pollen
  tube
• Generative nucleus divides into 2 sperm cells
  which remain inside the pollen tube

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Ovary

• Ovules form with a diploid cell
• Soon 4 haploid megapsores form
• Eventually get 8 haploid nuclei, but only 3 are
  most important
• 1 haploid nucleus egg
• Will combine with sperm nucleus to form the
  zygote
• 2 other nuclei are called polar nuclei
• Polar nuclei will fuse with sperm nucleus to make
  3n endosperm

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Pollination

• Pollen lands on stigma
• Pollen tube made from pollen grain
• Pollen tube grows down into the ovary
• When pollen tube reaches ovule, double
  fertilization occurs

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Double Fertilization

• Double fertilization is the union of 2 sperm
  cells forming zygote endosperm
• Unique to angiosperms
• 1 sperm fertilizes the egg ? zygote
• Zygote develops into the embryo ? sporophyte
• Other sperm combines with both polar nuclei 3n
  nucleus
• This 3n tissue ? endosperm
• Endosperm food storing tissue in the seed

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After double fertilization

• Ovule develops into a seed
• Ovary develops into fruit which encloses the seed
• Fruit protects the enclosed seed
• Fruit aids in dispersal by wind or animales
• Seed coat protects embryo its food supply
• Radicle embryonic root
• Epicotyl shoot tip with pair of miniature leaves

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Seed

• As the seed matures, It goes dormant
• Low metabolic rate, growth and development are
  suspended
• Seed resumes growth given suitable environmental
  conditions for germination