Date post: | 17-Jan-2016 |
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Plant Growth
Meristems
What environmental factors affect plant growth?
Environmental Factors…
• light
• nutrients
• temperature
• soil
• What was the factor that you studied in your lab?
Tropisms
• change in the growth of a plant in response to a stimulus
Phototropism
Gravitropism
Thigmotropism
Plant Growth Regulators
Auxins
• promote cell elongation
• occurs on “dark side” causing phototropism
Gibberellins
• action variable
• promotes cell division & elongation
• plays role in flowering & fruit production
• gibberellin spray induces fruit production & elongates fruit stems in grapes
Cytokinins
• promote cell division
• found in growing tissues such as meristems, young leaves, growing seeds
• slow cell aging
• sprayed on mushrooms & lettuce to prevent spoiling
Ethylene
• gas that is produced at various stages of plant growth
• “plant stress hormone”
• also stimulates fruit ripening, and many other developmental stages
• ethylene levels controlled so that fruit is ripe when sold at the store
Abscisic Acid (ABA)
• inhibits growth
• maintains dormancy in seeds and leaf buds
• levels rise in response to temperature & light changes (e.g., seasonal change)
• sometimes used on plants that are being shipped