What plants can we grow in space?

13 August 2019

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Question

What plants can we grow in space?

Answer

Food security expert Nadia Radzman from Cambridge University dug into the answer to Agasthya's question...

Nadia - Right. So what kind of plants? I'm guessing small enough plants to fit in the growth chamber that we currently have in the ISS, the International Space Station. So there is this small cabinet-size chamber that astronauts can grow plants in. So a couple of plants that had been grown before in space are lettuce, cabbage, Chinese cabbage, and also the model plant that we usually use in the lab called Arabidopsis thaliana - so it's a very small plant. A couple of these plants were grown for the astronaut consumption. So for example I think it was Chinese cabbage that they grew in the ISS and then they actually had to try... I'm not sure about that. But a lot of experiments, plant science experiments using Arabidopsis, are also being done in the ISS. So it's interesting that they were comparing how plants grow in space and on earth.

Chris - Because of course there’s microgravity in space, so these plants are growing in freefall, aren’t they. Is it true to say that plants actually depend on gravity in order to know what's up and what's down? And so therefore in the absence of a strong gravity signal, because they're in freefall, they're not gonna have that. So do they grow all wrong?

Nadia - So they don't exactly grow wrong. They do grow slower than the ones on Earth. And on Earth... so how plants detect where is the direction of gravity is that at the very end of the root tip, there are a group of cells, and these cells would actually detect where gravity is. So in microgravity in space these cells couldn't detect where's the direction of gravity anymore. So they would use light.

Chris - That’s the dominant signal is it? So they just obey where it's brightest and grow towards that?

Nadia - Yes. So the roots will grow away from the light and the shoots will grow towards the light. And it’s interesting, when they had a lot of light, when plants couldn't detect which direction that the lights are coming from, pretty much the roots and the shoots don't have any preference anymore.

Chris - So the answer is we're growing plants in space to see how they grow, but presumably because we're going to need them for food. Because plants are nature's solar panel. They get the energy from the sun, they turn it into chemical energy we can eat. So we're going to need plants in space if we're going to make space journeys. Maybe that’s the bottom line, isn’t it.

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