Sweetpotato Growth Using a Microporous Tube System with Lunar Simulant Medium

Abstract

Several plant growth systems have been tested for crop production in microgravity and lunar/Mars environments in support of NASA's Advanced Life Support Program and long-term human space missions. These systems have incorporated such design features as the nutrient film technique (NFT), microporous plates, microporous tubes, and expandable boundary chambers and have been developed and used to support sweetpotato production at Tuskegee University. In the present research, the performance of different sweetpotato cultivars in a microporous tube system with lunar simulant medium was studied. The lunar simulant is an inert aggregate with an average particle size of about 3 mm. Buried in this solid medium is a microporous tube. Nutrient solution is circulated through the microporous tube under a slight negative pressure. This pressure is controlled to allow a slight seepage from the tube with some accumulation of water in the solid medium, but no free water. A moisture sensor controls the desired flow rate of nutrient solution by adjusting a check valve to adjust the nutrient solution return to the reservoir in the system. The growth of two sweetpotato breeding lines and one cultivar (TU-155, NC58 and Georgia Jet) were studied and compared in the system. Preliminary observations indicate that storage root yields were highest with NC58 followed by TU-155 and then Georgia Jet. In contrast, vine length was the longest for Georgia Jet, followed by NC58 then TU-155. However, internode lengths were similar for the three cultivars. The system with its accessories is very simple to assemble and operated trouble-free for the 100+ days of a sweetpotato plant's growth cycle. Replicated experiments continue in order to test system performance in controlled environments.