Commercial Uses of Plant Hormones — AQA GCSE Biology (Separate)

Plant hormones are used in agriculture and horticulture to control plant growth for human benefit.

Uses of auxins

• Weedkillers (selective herbicides) — high concentrations of auxin make broad-leaved weeds grow too fast and die, without harming narrow-leaved crops/grasses.
• Rooting powders — auxins encourage cuttings to grow roots, so growers can produce many clones of a plant quickly.
• Promoting growth in tissue culture — auxins help cells grow and divide.

Uses of gibberellins

• Ending seed dormancy so seeds germinate when wanted.
• Promoting flowering.
• Increasing fruit size.

Uses of ethene

• Used in the food industry to control ripening of fruit. Fruit can be picked and transported while unripe (firmer, less easily damaged), then ripened with ethene at the destination.

Exam tips

• Match each hormone to its uses: auxins (weedkillers, rooting powder, tissue culture), gibberellins (germination, flowering, fruit size), ethene (ripening).
• Explain why selective weedkillers kill broad-leaved weeds but not grasses.
• Rooting powder uses auxin to produce clones from cuttings.
• Ethene lets fruit be transported unripe and ripened on arrival.