Astronauts could one day tend their own crops on long space missions, and Purdue University researchers have found a healthy candidate to help satisfy a sweet tooth - a strawberry that requires little maintenance and energy.
Cary Mitchell, professor of horticulture, and Gioia Massa, a horticulture research scientist, tested several cultivars of strawberries and found one variety, named Seascape, which seems to meet the requirements for becoming a space crop.
"What we're trying to do is grow our plants and minimize all of our inputs," Massa said. "We can grow these strawberries under shorter photoperiods than we thought and still get pretty much the same amount of yield."
Seascape strawberries are day-neutral, meaning they aren't sensitive to the length of available daylight to flower. Seascape was tested with as much as 20 hours of daylight and as little as 10 hours. While there were fewer strawberries with less light, each berry was larger and the volume of the yields was statistically the same.
"I was astounded that even with a day-neutral cultivar we were able to get basically the same amount of fruit with half the light," Mitchell said.
The findings, which were reported online early in the journal Advances in Space Research, showed that the Seascape strawberry cultivar is a good candidate for a space crop because it meets several guidelines set by NASA. Strawberry plants are relatively small, meeting mass and volume restrictions. Since Seascape provides fewer, but larger, berries under short days, there is less labor required of crew members who would have to pollinate and harvest the plants by hand. Needing less light cuts down energy requirements not only for lamps, but also for systems that would have to remove heat created by those lights.
"We're trying to think of the whole system -- growing food, preparing it and getting rid of the waste," Massa said. "Strawberries are easy to prepare and there's little waste."
Seascape also had less cycling, meaning it steadily supplied fruit throughout the test period. Massa said the plants kept producing fruit for about six months after starting to flower.
Mitchell said the earliest space crops will likely be part of a "salad machine," a small growth unit that will provide fresh produce that can supplement traditional space meals. Crops being considered include lettuces, radishes and tomatoes. Strawberries may be the only sweet fruit being considered, he said.
"The idea is to supplement the human diet with something people can look forward to," Mitchell said. "Fresh berries can certainly do that."
Judith Santini, a research statistical analyst in Purdue's Department of Agronomy, was responsible for data analysis from the tests.
Mitchell and Massa said they next plan to test Seascape strawberries using LED lighting, hydroponics and different temperature ranges. NASA funded their work.
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