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Sweetpotato (Ipomoea batatas) is an economic root crop that has been selected as a candidate crop to be grown on space missions by the U.S. National Aeronautics and Space Mission. This study determined the chemical and sensory behavior of hydroponically grown sweet potato (TU-82-155) during storage. Cured hydroponically grown sweet potatoes (HSP) were stored in palletized crates at 13°C and 80% RH for 42 days. Samples were randomly withdrawn at 0, 7, 14, 28, 35 and 42 days of storage for chemical, instrumental, and sensory analyses. Judges utilized a “just-about-right” attribute scale with five categories to assess the intensity of five sensory attributes. The HSP had a high moisture throughout storage, reflecting an overall mean of 82±2%. The mean fat and protein contents were 0.6±0.5% and 1.8±2%, respectively. The mean carbohydrate content was 15.2±3%, and the ash content ranged from 0.5±0.1% to 0.5±0.8%.

A mass balance nutrient management approach was used in controlled environment studies, to determine an appropriate nutrient solution replenishment regime for the growth of sweetpotato in nutrient film technique (NFT). Four stem cuttings (15-cm long) were planted into each of three gray PVC-1 (0.15×0.15×1.2 m) troughs in a walk-in growth chamber under a 14/10 h photoperiod, 28/22°C and 70% relative humidity. Photosynthetic photon flux at canopy level averaged 450-μmol m−2 s−1. Plants were grown with a modified half-Hoagland starter solution with an extra 3 mM of N for the first 4–6 weeks to accelerate vegetative growth, after which three refill solutions containing 1.5 (A), 4.5 (B), 0.75 (C), or 3 (A), 4.5 (B), and 6 (C) mM NO3−1-N and K, respectively, were used once per week until harvest. The level of N and K in the refill solutions did not significantly influence the number of storage roots produced.

Long-term manned space missions will require life support processes including food production. Porous plate and tube membrane systems have been identified to have potential for crop production in a microgravity environment. Of several systems tested, a stainless steel plate membrane system with a porous medium underneath has proven to be superior in terms of the uniformity of nutrient solution distribution. Several trials with sweetpotatoes, showed successful plant growth, with reduced foliage and storage root yield as compared to the nutrient film technique (NFT). These results can be attributed to reduced nutrient solution availability compared to NFT. It is expected that design improvements can increase sweetpotato yield..

A closed nutrient delivery chamber with expandable boundaries has been developed to support the growth of root crops, with potential applications in microgravity. The chamber is completely enclosed, separating the root zone from the foliage zone with a padded sealant through which the plant stem passes. The expandable boundary chamber (EBC) allows for expansion of the root zone volume, through longitudal pleats, as the plant grows. Two units have been evaluated with a trial crop of sweetpotato (Tuskegee Univ. breeding clone TU-82-155) for 120 days in a greenhouse environment. Storage root yield per plant in the EBC averaged 1.33 kg in comparison to 0.3 kg for the conventional Nutirent Film Technique (NFT) grown plants. This excellent yield warrants further design refinement and serious consideration of the system for earth use and microgravity applications.