Which factor is more important to root growth: gravity or water? To find out, scientists recruited astronauts to grow cucumbers on the International Space Station.

In the soil, roots seek out higher concentrations of water. The tendency is called hydrotropism. Roots also tend to grow downward as a result of gravity, a pattern called gravitropism.

But researchers haven't been able to determine which of the two influencing factors is the strongest.

When astronauts grew cucumbers in space, under microgravity conditions, the root patterns proved hydrotropism was the most important factor.

Scientists published the results of their experiments this week in the journal New Phytologist.

"We will be able to utilize roots' ability to sense moisture gradients for controlling root growth orientation and efficiently growing plants in future space farms," lead author Hideyuki Takahashi said in a news release.

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Counting calories in space
Paris (ESA) Jul 10, 2017
Rockets and spacecraft may get us to Mars, but food must nourish us on the journey. Now researchers are using the International Space Station to look at how much food will be needed on a spacecraft heading to the Moon, Mars or beyond. By tracking the energy used by astronauts, we can count the number of calories humans will need for long flights. Calculating total energy expenditure involv ... read more

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