Getting to the root of it!

Date posted: 01 November 2013

What happens below the surface is just as important as above when it comes to plants. Plant roots have the important job of finding and absorbing nutrients and water for growth and development.

Early days

When the barley grain first germinates, the first primary root known as a radical emerges. Shortly after, more primary roots appear, burrowing down in search of nutrients and water. Can you believe these roots can grow to depths of two meters!

Secondary roots

As the plant growth continues, a secondary root system develops. The secondary roots, known as adventitious roots, tend to develop in the tillering growth phase (refer to the Zadoks scale) as this phase requires plenty of water and nutrients to ensure the plant produces lots of grains.

In comparison to the primary root system, the secondary roots grow horizontally and tend to creep and sprawl around the top layers of soil. Their job is to soak up any surface water and acquire nutrients like phosphorus which are found more in the upper 10-20 cm of the soil.

Barley’s root growth continues right up until the grains on the plant begin to fill. Once the grains have filled, the roots work is done and they start to die off (barley is an annual plant don’t forget - so it only has a life span of one season).

Amazing plant root facts

  • Plant roots are covered in millions of tiny hairs to increase the surface area for absorbing water and nutrients. In the case of barley, the hairier the root the better. A plant with long, thin root hairs can absorb more so will survive better in harsh environmental conditions.
  • The tip of the plant root is protected by a nifty structure called a root cap. The root cap secretes a mucus type substance (mucilage) to help the root penetrate through the soil!
  • Root growth is affected by lack of water, acidic soil conditions, high levels of soil aluminium or compacted / dense soils which the roots can’t penetrate.

Activity

Dig up a plant in your garden (preferably a weed so your parents won’t mind!). Wash soil away from the roots and measure how far the root system has grown. See if you can tell the plants primary or secondary roots. For some great images and further information view the Barley Growth and Development book.