flowering floral induction
Download
Skip this Video
Download Presentation
Flowering - Floral Induction

Loading in 2 Seconds...

play fullscreen
1 / 32

Flowering - Floral Induction - PowerPoint PPT Presentation


  • 1209 Views
  • Uploaded on

Flowering - Floral Induction. violets, roses, chrysanthemums Chailakhan 1920’s Russian Florigen Amount of light and photoperiods already known to be important. Flowering - Floral Induction (branch bud ----> flower bud).

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Flowering - Floral Induction' - Thomas


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
flowering floral induction branch bud flower bud
violets, roses, chrysanthemums

Chailakhan 1920’s Russian

Florigen

Amount of light and photoperiods already known to be important.

Flowering - Floral Induction(branch bud ----> flower bud)
photoperiodism the ability of the plant to respond to different lengths of light treatment
Photoperiodismthe ability of the plant to respond to different lengths of light treatment
  • W. W. Garner & H. A. Allard - U. S. Ag. Dept. 1918…
  • Maryland Mammoth
    • large-leaved mutant
    • lack of flowering
    • greenhouse plants …various stages
      • most flowered in early December!
      • DAYLENGTH critical factor Short Day, Long Day, Day Neutral plants
short day plants
Short Day Plants
  • Flower only when day length is shorter than some critical value.
    • Pointsetta, cocklebur, soybean.. - qualitative
      • will not flower without a critical photoperiod
    • wheat, rye, .. - quantitative
      • will flower without a critical photoperiod but will take longer
short day plants1
Short Day Plants
  • Flower only when day length is shorter than some critical value.
    • soybean.. - qualitative
long and short day plants may flower at the same time
Long and Short Day Plants May Flower at the Same Time
  • Henbane (11 hrs.), Cocklebur (15 hrs.)
photoperiodism
PHOTOPERIODISM
  • Some plants need several days at the proper daylength. Winter & Summer Solstices
photoperiodism1
PHOTOPERIODISM
  • K. Hamner (U of Cal.) and J. Bonner (CIT) 1938
  • Sensitive light receiving system (pigment) at work.
  • Cocklebur:
    • 15 hrs of light/9 hrs dark = flowers
    • 15.5 hrs of light/8.5 hrs dark = no flowers
    • 15 hrs of light/9 hrs dark with interrupted dark = no flowering
  • (Dark period is more critical than light period for Floral Induction - initiation of floral primordia.)
photoperiodism2
PHOTOPERIODISM
  • K. Hamner (U of Cal.) and J. Bonner (CIT) 1938
photoperiodism redefined
PHOTOPERIODISM REDEFINED
  • K. Hamner (U of Cal.) and J. Bonner (CIT) 1938:
    • Short Day Plants
      • uninterrupted darkness must be of a certain duration.
      • (so much darkness or more)
    • Long Day Plants
      • uninterrupted darkness must be less than a certain maximum value.
      • (so much darkness or less)
    • Day Neutral Plants
      • Flowers at a certain level of maturity or in response to some environmental factor other than the photoperiod.
photoperiodism3
PHOTOPERIODISM
  • K. Hamner (U of Cal.) and J. Bonner (CIT) 1938
photoperiodism5
PHOTOPERIODISM
  • H. A. Borthwick and S. B. Hendricks 1950’s US Ag
photomorphogenic responses2
Photomorphogenic Responses
  • H. A. Borthwick and S. B. Hendricks 1950’s US Ag
    • Action spectra studies - flowering and others
    • Subjected plants to various wavelengths during dark period ----> responses
  • All photomorphogenic responses studied had similar responses …
  • Predicted: the photochrome pigment
    • 2 forms - 1.) PR - red light absorbing form
    • 2.) PFr - Far-red light absorbing form (Active Form)
photomorphogenic responses3
Photomorphogenic Responses
  • Phytochrome is ubiquitous in plants - found in all tissues. Has been isolated and purified.
  • Phycocyanin like
photomorphogenic responses4
Photomorphogenic Responses
  • Phytochrome Action Spectra:
photomorphogenic responses5
Photomorphogenic Responses
  • Mechanism of Phytochrome Action:
  • PR ---------------------------------------------> PFr
  • Red Light
  • PR <--------------------------------------------- PFr
  • Far-red Light
  • Half Life of PFr = 2.5 hours
  • (based on conformational changes in phytochrome)
photomorphogenic responses6
Photomorphogenic Responses
  • (3) Chromoproteins (chromatophore & apoprotein):
    • Phytochromes (5) PR & PFr
    • Cryptochromes Blue & UV
    • Photochromes Blue & UV
photomorphogenic responses7
Photomorphogenic Responses
  • Control of Gene Activation:
  • Actinomycin inhibits transcription & stops light responses
photomorphogenic responses9
Photomorphogenic Responses
  • Less etiolation with higher amount of PFr
  • Chenopodium alba “lamb’s quarter”
bud dormancy
Bud Dormancy
  • Wareing (1950’s) Fagus beech tree
    • initiated by short days
    • relieved by long days
    • reception site: leaf bud scales
bud dormancy1
Bud Dormancy
  • Initiation factors: photoperiod, lack of water, cold treatment (vernalization).
    • ABA - increases during bud dormancy
    • GA - decreases during bud dormancy
    • reception site: leaf bud scales
    • GA:ABA ratio a factor
seed dormancy
Seed Dormancy
  • Hard Seed Coat
    • prevents imbibition of water, gas exchange and growth
    • helps maintain the “seed bank”
    • Scarification
      • any treatment that breaks the seed coat
        • MECHANICAL (INSECTS)
        • ACID
        • FIRE
seed dormancy1
Seed Dormancy
  • Stratification
    • cold treatment of seeds
  • Ambient Factors:
    • 1.) temperature (near freezing, -2--> 7 degrees C)
    • 2.) time (7 --> 12 weeks …)
dormancy
Dormancy
  • Lange 1950’s
  • Hyoscyamous niger “henbane”
    • annual and biennial types
    • varied time and temperature of treatment for biennial
    • shorter vernalization, longer to flowering
vernalization stratification
Vernalization/Stratification
  • Petkus Rye - long day plant 15 1/2 wks to flower
    • spring annual
    • winter annual
      • also needs vernalization (and/or stratification)
      • flowers in 7 1/2 wks with cold treatment
vernalization stratification1
Vernalization/Stratification
  • Petkus Rye -
    • winter annual
deveralization destratification
Deveralization/Destratification
  • High temperatures (35 degrees C) are effective in devernalization/destratification if cold treatment is short.
ad