Chapter 3 Plant growth & Develpoment
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Transcript Chapter 3 Plant growth & Develpoment
Chapter 3 Plant growth &
Development
Growth Factors
Chemical Energy
Temperature
Photosynthesis
Respiration
Net Photosynthesis
Zone of tolerance
Optimum temperature
Nutrients & water
Growth Substances
Auxins
1st group of plant hormones to be discovered, mid
1930’s
Adventitious root initiation
Weed control (2-4D)
Inhibition of stem sprouting
Tissue culture
Gibberellins
Increasing fruit size of seedless grapes
Stimulating seed germination * seedling
growth
Promoting male flowers in cucumbers
Overcoming the cold requirement for some
plants
Cytokinins
No important agriculture use at this time.
DNA & RNA
Ethylene
Fruit ripening
Flower initiation
Changing sex expression (female flowers in
cucumbers & pumpkins)
Degreening oranges, lemons grapefruit
Harvest aids
Inhibitors
Abscisic Acid
Synthetic
Used to regulate plant growth
Growth inputs & quality
Timing
Amounts
Patterns of plant growth & development
Vegetative Phase
Reproductive Phase
Temperature & Vernalization
Some plants need lower temperatures for flower
induction
Temperature ranges are 32-500 F
Examples are cereal grains (wheat, barley, rye)
Some can be induced to flower by colder temps
(spinach, peas, lettuce)
Must reach a maturity before vernalization can begin
Hormone induced (gibberellins)
Look at table 3.1
Light & Photoperiod
Some plants needs a certain number of
hours of day length to flower
Short day plants (i.e. poinsettias,
strawberries, mums) need long nights
uninterrupted to flower
Long Day plants (i.e. spinach sugar
beets) need short nights
Day neutral (i.e. tomatoes)
Floral stimulus is transmitted form
leaves to meristem
Vegetative to flowering
Different photoperiods needed to induce
Once apex has changed to flower tissue
irreversible
Flower initiation to anthesis varies.
Flowering Response to Photoperiod
length of day
Long Day Plants greater than13 hours
Short Day Plants less than12 hours
Day Neutral Plants = no response
Look at table 3.2 & 3.3