Plants create water-rich spots around roots

UC DAVIS (US) — Soil scientists have shown for the first time that the soil around plant roots contains more water than does soil in other areas.

The findings, which contradict earlier beliefs that soil in the immediate vicinity of the roots has less water, could potentially lead to development of more drought-tolerant plants and more efficient irrigation systems.

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The results of the study appear in the October issue of the journal New Phytologist.

“Plants take water up from the ground by means of fine roots, a few millimeters in diameter,” says Ahmad Moradi, a postdoctoral fellow at the University of California, Davis.

“Their thicker roots serve more as pipelines, to relay the water. We want to understand the water distribution around these fine roots because this is the place where the roots remove water from their surrounding soil.”

At the Paul Scherrer Institute in Switzerland, an international research team led by Moradi used a method known as neutron tomography to create a precise three-dimensional image of water distribution around the plant roots and in other soil areas.

This technology allowed them to show the distribution of water to a fraction of a millimeter, without having to remove a plant from the soil.

“Neutrons are sensitive to water, and plant roots consist of around 90 percent water,” Moradi says. “When one wants to examine them, or the movement of water in the soil, neutrons are far better tools than X-rays.”

“It is probable that a gel-like substance that the roots exude is responsible,” says Andrea Carminati, a co-author at the University of Göttingen, Germany. “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.”

Funding for the study was provided by the European Union Marie Curie Water Watch Project.

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