4.5.4.2 - Use of plant hormones

List what are auxins used for?

• weed killers

• rooting powders

• promoting growth in tissue cultures

Describe auxin in weed killers

Weed killers - selective weed killlers have been developed using auxins , which only affect broad - leaved plants ( which are usually weeds camped to grasses and cereals which are narrow leaved) . The auxin totally disrupts their growth patterns and kills them

Describe auxin in rooting powders.

ooting powders - a cutting is a part of a plant that has been cut off. Adding rooting powder that contains auxins will ensure that a cutting produces roots rapidly and straits growing as new plants. Enables the growth of clones very quickly

Describe auxin in tissue cultures.

Gowing cells in tissue cultures - tissue cultures can also be used to grow clones of a plant from a few of its cells. Hormones like auxins are added to he growth medium to stimulate the cells to divide to form both roots and shoots

What are the uses of gibberellins?

• end seed dormancy

• Promote flowering

• Increase fruit size

Describe ending seed dormancy.

End seed dormancy -  seeds can be treated with gibberellin ti alter dormancy (when plants don’t grow due to certain conditions) and make them germinate at times of year that they wouldn’t normally. It also helps make sure all the seeds in a batch germinate at the same time

Describe inducing flowering.

Induce / promote flowering - if plan ts are treated with giberellins , they will flower without any change in their environment and it can also be used to grow bigger flowers

Describe larger fruit.

Growing larger fruit - seedless varieties of fruit often don’t grow as large as seeded fruit. So gibberellins can be used to grow these much larger to match the normal types

what is Stephen used for?

Ethene is used in the food industry to control the ripening of fruit during storage and transport :

give examples.

• commercially it can speed up the ripening of fruits which allows the fruit to be picked when its still unripe. So this means the fruit isles easily damaged and is fresh by the time it reaches a supermarket

• Ripening can also be delayed when the fruit is in storage by adding chemicals that block ethanes effect / react with then to remove it from the air