Plant Hormones

• Plants have to be able to respond to stimuli in their environment in order to survive, and they do it much more slowly than animals do.
• Plants can sense light and grow their shoots towards it to maximize photosynthesis.
• Plants can sense gravity so that they can grow their roots downwards to fix themselves into the soil and find more water and minerals.
• Some plants can even sense touch so that they can climb around other objects.
• Plants have to rely entirely on hormones to survive, as they don't have any nervous system like animals do.
• One group of these plant hormones are the auxins which control growth, the ends of the shoots and the roots.
• Auxins stimulate growth in shoots, causing the shoots to grow but inhibit growth in roots, leading to phototropism and geotropism respectively.
• Auxins accumulate on a shaded side rather than a sunny side and the lower side rather than the upper side.
• Shoots are positively phototropic, meaning they grow towards the light but negatively geotropic, growing away from the ground.
• Roots are negatively phototropic, growing away from the light and positively gravitropic, growing down towards the ground.
• Auxin is a judge type of growth hormone that stimulates plants to grow.
• Auxin can be used commercially to bring about changes in plants.
• Auxin can be used to stimulate growth in plant cells by adding it to a growth medium.
• Auxin can also be used to stimulate growth in cuttings, which are small sections of a plant that are being cut off like the end of a branch with a few leaves.
• If cuttings are placed in soil by themselves, they normally won't do anything but if a routine powder which contains auxin is added, they'll produce roots and start to grow into a new plant.
• Auxin can be used to kill weeds by adding enough of it, which can completely disrupt a plant's growth patterns and cause it to die.
• Gibberellin has three main uses: controlling dormancy, inducing flowering, and growing larger fruit.
• By exposing seeds to Gibberellin, new farmers can induce germination at times of the year when it wouldn't normally happen, allowing them to grow multiple crops per year and ensure that all the plants start growing at the same time.
• Gibberellin can also be used to induce flowering on demand and encourage plants to make more flowers or bigger flowers.
• The final use of Gibberellin is growing larger fruits, particularly useful with seedless varieties of fruit which naturally don't grow as large as a seeded relatives but by giving them Gibberellin we can make sure that their fruits grow well.
• Ethan is used to stimulate the ripening of fruit, as it works by stimulating an enzyme that causes the fruit to ripen.
• Most plants naturally produce their own Ethan and we often block its effects while we're transporting it so that it doesn't ripen too early.