L13: Plant Appearance Flashcards
Reasons for manipulating plant shape
- increase yield
- aesthetic value
- increase efficiency : labour elements
- lower fungi risk
Gravitropism
Regulated by auxins. Root=down, stem = upward. Roots are positively gravitropic and stems are negatively gravitropic
Apical Dominance
Central stem of the plant is dominant over side stems. Caused by apical bud producing auxin in abundance. Auxin causes lateral stems to be dormant.
Gibberellins
Growth hormones that stimulate cell elongation and cause plants to grow taller.
Gibberellins
Growth hormone. promote shoot growth, reduce flower formation. Shoot growth stimulates gibberellin production.
Factors stimulating bud break after shoot harvest
Removal of paradormancy
increased light intensity
increased red
Changed source/sink ratio
Heading
Remove part of a shoot/limb
Thinning
Remove entire shoot/limb
Disbudding
Gradually removing the flower buds that grow on the plant’s stem in order to enhance the lifespan and development of the remaining buds
Growth Retardents
Inhibits biosynthesis of gibberellins or blocks response to gibberellins.
Reasons for grafting fruit trees
- Lower tree height (easier for the work)
- Increase flowering
- Skip juvenile phase
DIF Concept
Difference night-day temperature.
Plants develop long stems under a combination of high day temperature and low night temperature.
Drop Concept
Sensitive to short period of temperature drop within circadian rhythm cycle. Usually to promote compaction (decorative plants). Morning most responsive to temperature decrease.
Biosynthesis
simple compounds are modified, converted into other compounds, or joined together to form macromolecules
Phytochrome
Photoreceptor used to detect light. Sensitive to light in the red and far-red region.
