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Other plant hormones - Higher

Plants can also respond to environmental factors using other hormones.

Gibberellins

are a group of plant hormones responsible for growth and development.

Gibberellins can be used to:

  • end seed
  • promote flowering
  • increase fruit size

Seed dormancy must be broken for seeds to germinate. Gibberellins are important for initiating seed in response to the seed being exposed to water.

They also stimulate cell and cause plants to grow taller.

Gibberellins cause , the production of flowers in an attempt for the plant to be able to reproduce before it dies. Bolting can happen if it is cold or there is a lack of water.

Gibberellins are naturally produced by seeds.

Sprouting seeds
Image caption,
Sprouting seeds

Fruit ripening

Unripe bananas
Figure caption,
Ethene causes bananas to ripen

is a gas which speeds up ripening in bananas and other fruit as well as causing dropping of leaves. It also controls cell division during plant growth.

In the food industry fruit is often picked unripe and then transported. This prevents fruit from over-ripening on the journey. It is ripened during storage by adding ethene and then taken to the shops.

The effect of ethene released from bananas is clearly visible if you keep them in a bowl with other fruit, as it causes other fruits to ripen very quickly.