Chapter 3 Plant growth

1
Chapter 3 Plant growth Development
2
Growth Factors

• Chemical Energy
• Photosynthesis
• Respiration
• Net Photosynthesis
• Temperature
• Zone of tolerance
• Optimum temperature
• Nutrients water

3
Growth Substances

• Auxins-
• 1st group of plant hormones to be discovered,
  mid 1930s
• Adventitious root initiation
• Weed control (2-4D)
• Inhibition of stem sprouting
• Tissue culture

4
Gibberellins-

• Increasing fruit size of seedless grapes
• Stimulating seed germination seedling growth
• Promoting male flowers in cucumbers
• Overcoming the cold requirement for some plants

5
Cytokinins-

• No important agriculture use at this time.
• DNA RNA

6
Ethylene

• Fruit ripening
• Flower initiation
• Changing sex expression (female flowers in
  cucumbers pumpkins)
• Degreening oranges, lemons grapefruit
• Harvest aids

7
Inhibitors

• Abscisic Acid
• Synthetic
• Used to regulate plant growth

8
Growth inputs quality

• Timing
• Amounts

9
Patterns of plant growth development

• Vegetative Phase
• Reproductive Phase

10
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

11
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)

12

• 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.

13
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