When considering space agriculture, it’s essential to remember that environmental conditions differ significantly from those on Earth: water is limited, radiation is an issue and gravity is altered. Identifying plants capable of adapting to such circumstances is a major challenge. However, Wolffia globosa seems to be a promising candidate.
Also known as duckweed, Wolffia globosa is the smallest known flowering plant. It grows in calm bodies of water and belongs to the Araceae family—ironically, the same plant family as Titan arum, which produces the largest inflorescence. Despite its size, Wolffia globosa produces a highly nutritious fruit, and grows rapidly. These traits make it an attractive option for space cultivation, where resources are limited, and efficiency is needed.
In order to test its potential for space farming, a research team led by Leone Romano grew seven duckweed clones under normal Earth gravity and simulated microgravity (as experienced in the spacecraft) and hypergravity (experienced during launching). They achieved microgravity and hypergravity conditions using special equipment known as a random positioning machine and a large-diameter centrifuge. Through the experiment, the researchers measured and compared the growth rate, protein content and morphological traits.
Although vascular plants tend to reduce their growth under microgravity conditions, duckweeds were shown to be more complex. The study found that some clones were resilient and others mildly affected by microgravity. This not only reinforces duckweed’s potential as a space crop but also highlights an important characteristic of the Araceae family: clonal variability. Similarly, under hypergravity conditions, some clones performed better and had significantly higher growth rates, whereas others were not affected. Whilst the reasons behind these different responses remain to be explored, these results emphasize the importance of clone selection in Wolffia globosa for space agriculture, especially because some of the clones were resilient to both treatments.
This study also shed some light into how duckweeds perceive and adapt to different gravity conditions. Although no differences were observed under microgravity, significant morphological changes were evidenced in the hypergravity treatment. Moreover, the researchers discovered a strong inverse relationship between growth rate and mean plant length—meaning that the smaller the plant, the faster its growth. This adaptive trait is particularly useful for extraterrestrial agriculture, where cultivation occurs in confined spaces with limited resources, making efficiency a priority.
Finally, it was observed that duckweeds maintained their protein content under hypergravity conditions. However, this was not the case in microgravity conditions where plants experienced a decrease in protein content. This is something that might challenge the cultivation of Wolffia globosa in space. Nonetheless, the authors remark that protein content can be optimised by changing light quality and quantity, liquid substrate and nutrient medium during cultivation.
Something that feels straight out of a Jules Verne novel is now being studied by scientists. Hopefully, this and other research will bring space exploration closer to reality and further from science fiction. For now, Wolffia globosa seems like a promising candidate for space farming and space food—the smallest plant on Earth, helping us explore the vastness of the universe.
READ THE ARTICLE:
Romano, L.E., Loon, J.J.W.A., Vincent-Bonnieu, S. and Aronne, G., 2024. Wolffia globosa, a novel crop species for protein production in space agriculture. Scientific Reports, 14. https://doi.org/10.21203/rs.3.rs-4317398/v1.
Paula Erazo
Paula is an enthusiastic biologist with a deep curiosity about life and everything around her. With a Master’s in Science Communication, she loves sharing the wonders of the natural world. Follow her and her science communication team on Instagram at @cienciatropical
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