Plant Growth Regulators

1
Plant Growth Regulators
2
Fertilizers and Growth Regulators

• plant growth regulator
• organic compound (natural or synthetic)
• Modifies/controls one or more physiological
  processes related to growth
• Natural Hormones made by and stored in plants
• Synthestic applied to plant environment or genome

• FERTILIZER
• Plant nutrients utilized in synthesis of
  biochemicals
• Used directly in bioaccumulation
• Example Nitrates used in amino acid
  construction
• Acquired from environment

3
Auxin

• Family of compounds used in growth stimulation
  and inhibition
• Used directly in cell elongation
• Phototropism movement toward light

Auxein (Greek) to grow
4
Auxins in Phototropisms
5
Auxins and Apical Dominance

• Auxins made in apical meristem
• Diffuse down to lateral buds
• High concentration Apical growth
• High concentration lateral inhibition
• Apical bud removed decrease in auxins and
• lateral growth
• Pruning may result in bushy growth

6
Plant Growth Regulators and

• Rooting stem cuttings can be grown by inducing
  rooting at the base more productive than growth
  from seeds
• Weed removal some auxins target broad-leaved
  plants (thistle, mint, etc.) effective in grass
  fields (wheat and corn)
• Fruit ripening Ethylene made by one ripened
  fruit or released artificially hastens ripening
  in other fruits. one bad apple
• Seedless Fruits Gibberellins used to
• 1. Induce fruit growth from unfertilized ova
• 2. Grow larger fruits since seedless fruits
  tend to
• be smaller (seeds regulate hormonal growth)

7
Cloning by Micropropagation
Viral or fungal free stock - millions from
one desirable cultivar

• Initiation stage A piece of plant tissue is cut
  and placed in nutrient (minerals, sucrose, agar)
• Multiplication stage Vegetative growth induced
  by addition of cytokinin (promotes shoot
  formation from growing plant cells).
• Rooting stage Induced to produce adventitious
  roots by including an auxin in the medium.
• Acclimatization Growing, rooted shoot removed
  from tissue culture and placed in soil weaned
  from humidity as new cultures are prone to wilt.