大象传媒

Plant hormones - OCR Gateway Other plant hormones - Higher

Hormones control important processes like germination, flower opening, dropping leaves, phototropism and geotropism. We use plant hormones in weedkillers, and to make seedless fruit and root cuttings.

Part of Biology (Single Science)Organism level systems

Other plant hormones - Higher

, which are a group of plant hormones responsible for growth and development, are important for initiating seed . Low concentrations can be used to increase the speed of germination, and they stimulate cell and cause plants to grow taller.

They are naturally produced by seeds.

Sprouting seeds
Image caption,
Gibberellins are responsible for initiating seed germination

Gibberellins can be used to:

  • end seed dormancy
  • promote flowering
  • increase fruit size
A tree with unripe bananas
Figure caption,
Ethene gas acts as a hormone to speed up ripening in bananas and other fruit

Seed must be broken for seeds to germinate, and this can be done by using gibberellins.

Controlling fruit ripening

is a gas which speeds up ripening in bananas and other fruit. 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 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.