Control and coordination

Plants produce hormones to coordinate and control growth and responses to light (phototropism) and gravity (gravitropism or geotropism). Unequal distributions of auxin cause unequal growth rates in plant roots and shoots.

Use of plant hormones

Students should be able to describe the effects of some plant hormones and the different ways people use them to control plant growth.

Plant growth hormones are used in agriculture and horticulture.

Auxins are used:
- as weed killers
- as rooting powders
- for promoting growth in tissue culture.

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

Gibberellins can be used to:
- end seed dormancy
- promote flowering
- increase fruit size.