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Plants can reproduce both sexually and asexually' Most organic crops are grown from sexually produce

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Plants can reproduce both sexually and asexually' Most organic crops are grown from sexually produce – PowerPoint PPT presentation

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Title: Plants can reproduce both sexually and asexually' Most organic crops are grown from sexually produce


1
Plant Applications
  • Plants can reproduce both sexually and asexually.
    Most organic crops are grown from sexually
    produced seed, though fruit and nursery crop
    reproduction often involves asexual methods of
    propagation.

2
Structure of a Seed
3
Factors in Seed Germination
  • Light
  • Moisture
  • Temperature

4
Light
  • Requirements of different seed differ.
  • Some need only a flash.
  • Example - weed seed
  • Some need continuous light.
  • Example lettuce seed- dont have to be on the
    surface, however

5
Moisture
  • Seed vary in amount of moisture needed.
  • Most agricultural crops need moist conditions,
    but not be surrounded by water.
  • Some require continuous moisture till germination
    which may take 10 days example- parsley and
    carrots.

6
Temperature
  • Plants vary in the optimum
  • temperature they require
  • for germination.
  • Most will germinate over a range
  • of temperatures, with the optimum percentage of
    germination at some particular temperature.
  • Example optimum temperature for spinach is 72
    degrees, optimum for peppers is 86.

7
Special techniques
  • Some seeds need special procedures to overcome
    their dormancy
  • Nicking or filing the seed coat morning glory
  • Cold treatment many perennial flowers such as
    echinacea
  • Varying hot and cold
  • treatments

8
Humic acids
  • Recent research has shown that humic acids can
    stimulate germination.
  • Humic acids are found in compost.
  • Covering the seed with compost, especially
    vermicompost, can increase speed and percentage
    of germination.

9
Propagation by seed
  • Most agricultural crops are sown from seed.
  • Root crops, grains and legumes are sown in the
    field.
  • Root crops do best when sown in the field as
    their roots do not like to be disturbed.
  • Legumes and grains are sown thickly and germinate
    quickly.

10
Implements for seed sowing
  • Hand held broadcasters
  • Push seeders
  • Tractor mounted broadcasters
  • Hand seed sower
  • Large volume vacuum seeders
  • Pictures from Johnnys website

11
Transplants
  • Disadvantages of growing
  • from transplants
  • More time and effort required
  • Greenhouse or other protected place necessary
  • More resources in soil mix and flats
  • Transplants must be watered in
  • Advantages of growing from transplants
  • Accurate spacing
  • Ability to choose best plants
  • Ability to control conditions of germination
  • Earlier planting

12
Soil Mixes
  • Most commercially produced mixes contain chemical
    fertilizers and are not allowed in an organic
    operation.
  • Organic soil mixes are becoming more available.
  • Home made mixes allow you to tailor the mix to
    your crops.

13
Ingredients in soil mixes
  • Peat moss
  • Perlite
  • Vermiculite
  • Sand
  • Compost
  • Soil
  • Organic amendments to
  • add fertility

14
Soil Blocks
  • Eliot Coleman method to avoid using plastic pots
    or plug trays.
  • Mix soil, add water to make soupy- like cake
    batter, use blocker to make block, place close
    together in tray.
  • Plant seed in indention
  • on top.
  • Water gently to
  • preserve the block.

15
Asexual Propagation
  • Original by Linda Rist
  • Modified by Georgia Agricultural Education
    Curriculum Office
  • July, 2002
  • Modified by Georgia Organics
  • February 2008

16
Softwood Semi-hardwood stem cuttings
  • Take cuttings after current or present seasons
    growth has partially hardened.
  • Stem should still be flexible.
  • Parent plant that has made 2 to 6 inches new
    growth during current year.
  • Early morning is the best time to take cuttings.

17
Stem Cuttings
  • To remember which is the top of the cutting
  • cut bottom at an angle.
  • cut top straight across.
  • Place cuttings in water as they are cut.
  • Include 2-3 buds on each cutting.
  • Once all cuttings are made, insert in rooting
    media use sand or perlite.
  • Containers must have holes in the bottom for
    drainage.
  • Auxin is the hormone which promotes rooting.
  • Rootone is non-organic source of auxin.
  • Willow extract is organic source of auxin.

18
Stem Cuttings
  • Keep relative humidity close to 100 by
  • placing plastic or glass over flat.
  • Keep temperature relatively low and out of direct
    sunlight.
  • Check for roots by holding cutting and tugging
    gently, resistance - roots developing.
  • Growth on the tips or sides is normal, but does
    not indicate root growth.
  • Harden off when root ball is 2-3 inches.
  • After hardening off, cuttings can be planted
    outside.

19
Root Cuttings
  • Can be made from any plant that will
  • sprout or sucker from the root.
  • Cut roots 1/8 to 1/2 inch in diameter, in pieces
    1-4 inches long.
  • Place cuttings in a flat of sand, water and cover
    with glass or plastic.
  • When new shoots sprout move plants to nursery
    row.
  • Example raspberry

20
Asexual propagation methods
  • Root, stem or leaf cuttings
  • Root raspberry
  • Stem angel trumpet
  • Leaf jade plant, Christmas cactus
  • Dividing a tuber
  • Potato
  • Layering
  • Hydrangea
  • Grafting
  • Heirloom tomatoes
  • Fruit trees

21
Transpiration stream application
  • Wilting when there is adequate water.
  • Caused when transpiration is more rapid than
    water uptake by roots.
  • Lettuce, other plants with large leaf areas.
  • Especially when drip irrigation used.
  • Overhead watering can lower temperature and
    transpiration.

22
Summary
  • 1. Describe the structure a seed.
  • 2. List the three requirements for germination of
    most seeds.
  • 3. State the effect of humic acids on germination
    and where they can be found.
  • 4. List three benefits to starting seeds in flats
    in a greenhouse.
  • 5. Describe ways to get an acceptable organic
    soil mixture.
  • 6. Identify the hormone important in stimulating
    rooting of cuttings and where it can be found.
  • 7. List three other ways to asexually propagate
    plants.
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