5.5.4: Commercial uses of plant hormones Flashcards
What can artificial auxins be used for?
-Preventing leaf and fruit ‘drop’
(useful if there are too many small fruits that are hard to sell, the plant produces fewer, larger fruits)
-Promote flowering.
How are auxins used when taking cuttings?
- Dipping ends of a cutting in rooting powder encourages root growth.
- Contains auxins and talcum powder.
How are auxins used tp promote the growth of seedless fruit?
- Treating unpollinated flowers with auxin promotes growth of seedless fruit.
- Auxin promotes ovule growth which triggers the automatic production of auxin by tissues in the developing fruit, helping to complete the developmental process.
How are auxins used as herbicides?
- to kill weeds.
- Man-made so plants find them hard to break down and they can act within the plant for longer
- promote shoot growth so much that the stem cannot support itself, buckles and dies.
Why are cytokinins used to prevent the yellowing of lettuce after being picked?
They can delay leaf senescence.
Why are cytokinins used in tissue culture to help mass-produce plants?
- Cytokinins promote bud and shoot growth from small pieces of tissues taken from a parent plant.
- This produces a short shoot with a lot of side branches, which can be split into lots of smaller plants.
- Each of these is then grown separately.
How are gibberellins used in citrus fruit production?
-They delay senescence in citrus fruit, extending the time fruits can be left unpicked, and making them available for longer in the shops.
How are gibberellins acting with cytokinins involved in apple production?
-They make apples elongate, improving their shape.
How are gibberellins used in grape production?
- Without gibberellins, bunches of grapes are very compact which restricts growth.
- With gibberellins, the grape stalks elongate, they are less compacted, rapes get bigger.
When barley seeds germinate, what does the aleurone layer of the seed produce?
-Amylase enzymes that break down the stored starch into maltose.
What are the genes for amylase production in barley seeds switched on by?
- Naturally occurring gibberellins.
- Can be sped up by adding gibberellins.
Wy are sugar canes sprayed with gibberellins?
- Stimulates growth between nodes making stems elongate.
- Useful as sugar cane stores sugar in the cells of the internodes.
- More sugar is available from each plant.
How are gibberellins used in plant breeding?
-By inducing seed formation from young trees.
How can plants be made to stop producing gibberellins?
-Spraying plants with gibberellin synthesis inhibitor.
WWhy can preventing plants from producing gibberellins be useful?
- Keeps flowers short and stocky.
- Ensures internodes of crop plants stay short, helping to prevent lodging.
