Plant hormones

• Auxin


  Accumulates at the tips of growing shoots and roots
• Auxin accumulation


  Diffuses back across the roots and shoots
• Auxin accumulation in shoots


  Stimulates growth in the shoot
• Auxin accumulation in root


  Inhibits growth in the root
• Auxin always accumulates at a lower shaded side
• Positively phototropic


  Grows towards light
• Negatively geotropic


  Grows away from the ground
• Auxin


  A type of growth hormone that stimulates plants to grow
• Using auxin commercially


  1. Add auxin to plant cells in tissue culture to stimulate growth

  2. Add auxin powder to plant cuttings to stimulate root growth

  3. Add high levels of auxin to disrupt plant growth and kill weeds
• Most commercial plants like cereals are narrow-leaved, while most weeds are broad-leaved
• Gibberellin


  A plant hormone used to control dormancy, induce flowering, and grow larger fruit
• Using gibberellin commercially


  1. Expose seeds to gibberellin to induce germination

  2. Apply gibberellin to induce flowering or produce more/larger flowers

  3. Apply gibberellin to seedless fruit varieties to make them grow larger
• Ethene

  A plant hormone used to stimulate the ripening of fruit
• Using ethene commercially


  Apply ethene to ripe fruit to quickly ripen it for sale, after transporting unripe fruit
• Ethene works by stimulating an enzyme that causes the fruit to ripen