Plant growth regulators
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CBSE NOTES, QUESTIONS, ANIMATED TUTORIALS

CBSE NOTES, QUESTIONS, ANIMATED TUTORIALS
www.cbse123.co.nr
http://sites.google.com/site/cbseathome
www.students-learn.blogspot.com

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Plant growth regulators Plant growth regulators Presentation Transcript

  • Plant Growth Regulators
    MR. NARENDER VERMA (PGT BIO)
    KV- TAWANG
    A. P.
    Presented By:
    www.cbse123.co.nr And http://sites.google.com/site/CbseAtHome
  • What are the two groups of plant growth regulating compounds?
    Natural vs. Synthetic
    Natural- found naturally in plants
    Synthetic- human made
    Both groups regulate or influence:
    Cell division
    Cell differentiation
    Root and shoot growth
    Senescence (plant aging)
  • Promoters vs. Inhibitors
    Promoters- cause faster growth
    Inhibitors- reduce growth
  • What is the difference between synthetic growth regulators and plant hormones?
    Hormones
    plant produced natural compounds that inhibit or promote plant growth
    Major classes of plant growth regulators (hormones) are:
    Auxins
    Gibberellins
    Cytokinins
    Abscisic acid
    Ethylene
  • Auxins
    Growth promoting chemicals
    Promote cell division and cell elongation
    Primary plant auxin is indoleacetic acid (IAA)
    Common synthetic forms of auxins are indolebutyric acid (IBA) and naphthaleneacetic acid (NAA)
    Useful in phototropism, geotropism, apical dominance, and root formation
    Phototropism- plant growth toward a light source
    Geotropism- plant growth in response to gravitational forces
    Apical dominance- terminal buds prevent the development of lateral buds on plant stem
  • Gibberellins
    Also known as Gibberellic acid or GA
    Growth promoting chemicals
    Stimulate stem growth through cell elongation and cell division
    Commercial supplies obtained from the fungus Gibberella fujikuroi
  • Cytokinins
    Promote cell division and delay leaf aging
    Used as a growth promoter in tissue culture
    Slows the process of senescence (biological aging) by preventing the breakdown of chlorophyll in leaves
  • Abscisic acid (ABA)
    Only natural plant growth inhibitor
    Growth inhibitor that closes the stomates of plants under water stress
    Counteracts the effects of auxins and gibberellins
    Cycocel and B-Nine are two synthetic ABA type growth inhibitors commonly used
  • Ethylene
    Gas that forms in tissue undergoing stress
    Important in the fruit-ripening process and early petal drop of flowers
  • How do plant hormones control apical dominance?
    Apical dominance
    Controlled by auxins where the terminal bud inhibits the development of lower lateral buds
    In greenhouses, we pinch the terminal bud out of a plant so that the plant branches out and becomes bushy
    Phototropism
    Controlled by auxins, which is a plant’s response to grow toward light
    Geotropism
    Plant growth response to gravity
  • What are the benefits of using plant growth regulators?
    Benefits
    Promote and accelerate root formation on cuttings
    Keep fruit on trees longer to allow further ripening achieved by the application of auxin
    Thin blossom clusters and increase berry size in grapes- achieved by the application of gibberellic acid
    Increase size and crispness of stalks of celery- achieved by the application of GA
    Control the size of plants
  • What are the different types of rooting compounds?
    Rooting compounds
    Indoleacetic acid (IAA)- naturally occurring auxin that produces bushy, stunted root systems
    Indolebutyric acid (IBA)- synthetic form of auxin that produces strong, fibrous root systems
    Napthaleneacetic acid (NAA)- synthetic form of auxin similar to IBA
  • Increase the number of flower buds formed
    Improve the number of flower buds formed
    Improve the longevity and quality of cut flowers
    Control vegetative growth and reduce mowing frequency in turfgrass
    Reduce or eliminate unwanted sprouts and suckers
    Reduce pollen, for people with allergies, by eliminating flowers on some trees, which also can control unsightliness and odor caused by falling fruit
    Control the growth of shrubs and hedges
  • Regulators reduce amount of mowing needed
    Reduces number of mowings per year
    Reduces labor and machinery costs
    Growth regulators beneficial to:
    1. Lawn care operators
    2. Cemetery managers
    3. Golf course superintendents
  • When should growth regulators be applied?
    Timing of application can affect how various regulators do their job & their affect on non-targeted plants
    Ex. Embark should be applied after spring “green-up but before seedhead emergence
    Some chemical may be washed away if applied before a rain or watering
    Be sure to read the label to find out when to apply!!!
    If a crop is edible, how would application affect harvest date?
  • What are gibberellins and anti-gibberellins?
    Gibberellins- promote plant growth
    Anti-gibberellins- counteract the effect of naturally occurring gibberellins
    Can reduce the rate of growth in shade trees
    Used be utility companies to control trees that may grow into utility lines
    How else could anti-gibberellins be used?
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    STUDENTS-LEARN