Plant hormones in agriculture and horticulture (Pg 37)

Plant hormones in agriculture and horticulture (Pg 37)

1. Plant hormones can be applied to plants to either speed up or slow down their growth.

2. Weedkillers

   • Auxins are used as selective weedkillers. Agent orange was used in the Vietnam war. It made trees loose their leaves. Without leaves, plants cannot make food and the trees die.

3. Rooting powder

   • If cuttings are dipped into auxin powder, this helps the cuttings make new roots. With new roots the cuttings can anchor in the soil and take up water and minerals.

4. Fruit ripening

   • Auxin can be sprayed onto fruit trees to prevent the ripe fruit from dropping. Then it can all be harvested at the same time and the fruit is not bruised by falling on the ground. If a high dose of auxin is sprayed later, it makes the fruit fall.

5. Control of dormancy

   • Seeds are usually dormant when they are shed from the parent plant. This stops them germinating at the end of the summer, as new plants may not survive the harsh winter. However if commercial growers want to germinate seeds in green houses during winter, applying auxin can break the dormancy.