Sweet potato takes a ride on space shuttle Columbia

Study shows roots can regenerate in microgravity

TUSKEGEE, AL—Because of the distinct lack of grocery stores in outer space, scientists are looking for ways to provide food for long-term space missions.

Desmond G. Mortley and colleagues from the Center for Food and Environmental Systems for Human Exploration of Space, G.W. Carver Agricultural Experiment Station, and the Kennedy Space Center undertook a study on microgravity's effects on sweetpotato. The study findings were published in the Journal of American Society for Horticultural Science.

Seeds of several crops have been grown in microgravity, but this was the first test for plants grown from cuttings. Cuttings grow roots faster than do seeds, and sweetpotato cuttings regenerate very easily. This made them ideal for the study, half of which took place on a 5-day space mission on the shuttle Columbia.

The other half of the cuttings remained on earth as the ground-based control group at Kennedy Space Center in Florida. Conditions were similar for both growing environments.

Both environments resulted in similar root growth development, though the microgravity roots tended to grow perpendicular to the cuttings. The number of roots was almost the same in both samples. However, the length of roots grown in microgravity was significantly greater. Microgravity cuttings contained significant accumulation of soluble sugars and higher starch concentration than ground cuttings; the starch grains appeared smaller in microgravity samples.

Despite these differences, the study was successful in showing that stem cuttings, at least those started in normal gravity conditions, can regenerate roots in microgravity. "This suggests that the space flight environment has no negative effect on the ability of vegetative cuttings to form roots and that use of cuttings should be an acceptable means for propagating sweetpotato for future space applications," summarized the researchers.

The next step will be to experiment over longer space missions to test root cuttings' ability to grow plants.

The complete study and abstract are available on the ASHS J. Amer. Soc. Hort. Sci. electronic journal web site: http://journal.ashspublications.org/cgi/content/abstract/133/3/327

Founded in 1903, the American Society for Horticultural Science (ASHS) is the largest organization dedicated to advancing all facets of horticultural research, education, and application. More information at ashs.org