plant hormones

• Hormones:

  • Giberrelins

  • Auxins

  • Ethene
• Selective weedkillers (auxins):

  • Weed plants compete with crop plants for minerals and water from soil

  • Auxins stimulate growth of roots which causes one type of plant to grow too quickly and die
• Rooting powder (auxins):

  • Cuttings of plants to grow into new plants

  • Dip stalk end into rooting powder contains auxins so the roots are produced quickly
• Giberrelins:

  • Stimulates germination of seeds which increases crop yields

  • Stimulates cell elongation

  • Sprayed in flowers for large seedless fruits

  • Increase in costs
• Ethene:

  • Hydrocarbon gas that speeds up ripening in fruits
• Tropism is the growth in plant in response to the stimulus
• Gravitropism:

  • Stimulus is gravity

  • Positive response, the roots grow

  • Negative response, the shoots grow
• Phototropism:

  • Stimulus is light

  • Positive response, the shoots grow

  • Negative respone, the roots grow
• In stem, the shaded side contains more auxins snd grows longer which causes the stem to grow towards light.
• Drawbacks:

  • Harmful to environment and non-target species

  • Overuses can cause resistance which reduces effectiveness