Download 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


