X-ray vision of

Numbered X ray images of peas grown container filled with fine potting mix, showing a fairly even distribution. Older parts of the roots are coloured red, and new root growth is coloured green.

An X-ray technique developed for industrial applications has been put to work to watch living roots grow.

According to CSIRO Land and Water scientist Mac Kirby, until now scientists wanting to measure root growth have been forced to peer down small tubes in the ground, or wash roots out of the soil, and neither technique lets you watch the roots grow. Other techniques, such as setting the soil in a resin, actually kill the roots.

"We can now take X-ray images of the roots across many days, or even weeks, and actually see where they are growing," says Dr Kirby

For scientists this is an impressive development. It means that they can now see in real-time the effect of soil structure, such as different-sized macropores (gaps between soil particles) on root growth, or they can watch a young plant trying to emerge through a soil crust.

Questions like 'what sort of soil structure do roots need to be able to thrive?' can now be answered in new detail. Dr Kirby says his group is one of the few in the world able to see roots to such a fine resolution. Although the work is currently confined to looking at root growth in specially designed containers, in a few years it will be possible to obtain high-resolution 3D images of root growth in large plant pots.

The ultimate goal is to use this technique to measure root growth in a real-world crop as easily as can be done with leaves. While that's still out of reach, the current technical advance should provide plenty of answers

Program 3.4.2

Contact: Dr Mac Kirby 02 6246 5921