Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Plants create a water reserve in the soil

15.09.2011
Experiments performed at the Paul Scherrer Institute (PSI) reveal that a zone of higher water concentration exists around the roots of a plant.

It has long been known that roots alter the soil in their immediate vicinity, where other microorganisms live and the chemical composition is altered compared to that further away from the roots.

An international research team has now demonstrated in experiments at the Paul Scherrer Institute that the soil in the vicinity of roots also contains more water – contrary to the earlier belief that there must be less water in this region, as the plant takes up water from the soil. Apparently, however, plants create a small water reserve that helps to tide them over through short periods of drought. These findings could help, in the long term, in the breeding of plants to cope better during periods of drought or in support of the development of efficient irrigation systems. These results were obtained from experiments carried out with the benefit of neutron tomography at the Paul Scherrer Institute, using a method that makes it possible to exactly show the distribution of water to a fraction of a millimetre, without having to remove a plant from the soil. The researchers have published their results in the prestigious journal New Phytologist.

"The question of how plants take up water is not only relevant to the development of new, water-efficient strains of plants, but also for improving climate models," explains Sascha Oswald, from the Institute of Earth and Environmental Science at the University of Potsdam, "because typically more than half of all the water that falls onto the earth's surface as rain in a humid climate is taken up by plants and then passes back to the atmosphere through the plants." A research project at the Helmholtz-Centre for Environmental Research - UFZ where he worked with a number of colleagues had the goal of showing what exactly happens at the place where a plant takes up water through its roots. "Plants take water up from the ground by means of fine roots, a few millimetres in diameter. Their thicker roots serve more as pipelines, to relay the water. We want to understand the water distribution around these roots," explains Ahmad Moradi, from the University of California Davis.

Neutrons reveal water content without damaging plants
"The decisive processes occur here at a scale of a few millimetres. In order not to miss these processes, we need a procedure that shows details that are smaller than a millimetre and that can be applied without needing to remove the plant from the soil," says Moradi of the technical challenge. The researchers found the appropriate method at the Paul Scherrer Institute in the form of neutron tomography. Here, they were able to send neutrons through plants, together with the soil around their roots. Using these particles, it is possible to see inside different objects, in a similar manner to using X-rays but making different internal components visible. Specifically, neutrons are particularly attenuated and scattered away by water, whereas metal or sand are essentially invisible to them. "Roots consist to almost 90% of water. When one wants to examine them, or the movement of water in the soil, then neutrons are far better tools than X-rays," explains Moradi.

The researchers were thus able to create an exact three-dimensional image of the water distribution around the roots and determine how much water was present at different positions in the soil. "The microscope option of the facility was used for this measurement, so that images with a resolution of 20 pixels per millimetre could be generated. In this way, it was possible to make the water visible to the required accuracy," explains Eberhard Lehmann, whose group operates the facilities at PSI. "We have three measurement stations at which we can create images with neutrons - each with its own characteristics. Thus we were able to try out different options for the experiment. A great advantage of the PSI facility is also that it is in operation 24 hours a day, and thus plants could be observed over a complete day-night cycle." PSI is the only centre in Switzerland at which neutrons are available for research.

More water at the roots
The result obtained from this study is that the soil in a region within a few millimetres from roots contains about 30% more water than the rest of the soil. It has long been known that roots significantly alter their immediate environment. In this so-called rhizosphere a much higher number of different microorganisms than elsewhere can be found. They profit from organic root excudates. "Because of the water uptake by roots it has been assumed as a matter of course that the water content close to the roots is decreased and that water is flowing along a gradient towards the roots" explains Hans-Jörg Vogel from the Department of Soil Physics at UFZ. . The experiments contradicted this belief, for all three types of plants tested - maize, lupines and chick peas.
Water reserve for bad times
"We can now only speculate about the question as to how the water concentration around the roots becomes higher. It is probable that a gel-like substance that the roots exude is responsible. This substance can absorb 10,000 times its own dry weight of water. In this way, plants could create an emergency supply for short periods of drought," explains the soil physicist Andrea Carminati, from the University of Göttingen. Even if this emergency supply does not suffice for longer periods of drought, it can help cover periods of up to 12 hours in which the plant would otherwise be cut off from a supply of water. "If one thinks about the practical applications of these results, then they can help in the breeding of plants which can survive dry periods better. One could also learn exactly how much to water plants, so that they do not come to long-lasting harm through drying out," adds Sascha Oswald.
The project
This research project was carried out by scientists from the Helmholtz Centre for Environmental Research - UFZ, the University of California Davis, the University of Potsdam and the University of Göttingen, who had all previously worked together at the UFZ. The experiments described here were performed at the Paul Scherrer Institute, PSI (Villigen, Switzerland) and supervised by PSI scientists.
Links:
http://www.ufz.de/index.php?de=22115
http://www.psi.ch/media/pflanzen-schaffen-sich-wasservorrat-im-boden
Contact:
Dr. Ahmad Moradi, Department of Land, Air and Water Resources,
University of California Davis, Davis, CA 95616, USA
E-Mail: amoradi@ucdavis.edu; Tel: +1 530 752 1210
Dr. Eberhard Lehmann, Group Leader of Neutron Imaging,
Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
E-Mail: eberhard.lehmann@psi.ch; Tel: +41 56 310 29 63
Prof. Dr. Sascha Oswald, Institute for Earth and Environmental Science,
University of Potsdam, 14476 Potsdam-Golm, Germany
E-Mail: sascha.oswald@uni-potsdam.de, Tel: +49 331 977 2675
Dr. Andrea Carminati, Department of Crop Sciences,
Georg-August University of Göttingen, 37018 Göttingen, Germany
E-Mail: acarmin@uni-goettingen.de, Tel: +49 551 39 4629
Prof. Dr. Hans-Jörg Vogel, Helmholtz-Centre forEnvironmental Research - UFZ, Department Soil Physics. 06120 Halle, Germany.

Tel: +49 345 558 5403

Paul Piwnicki/Tilo Arnhold | UFZ News
Further information:
http://www.ufz.de/index.php?de=6171

More articles from Life Sciences:

nachricht For a chimpanzee, one good turn deserves another
27.06.2017 | Max-Planck-Institut für Mathematik in den Naturwissenschaften (MPIMIS)

nachricht New method to rapidly map the 'social networks' of proteins
27.06.2017 | Salk Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Touch Displays WAY-AX and WAY-DX by WayCon

27.06.2017 | Power and Electrical Engineering

Drones that drive

27.06.2017 | Information Technology

Ultra-compact phase modulators based on graphene plasmons

27.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>