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GENERATION OF EDIBLE BIOMASS BY THE DEPLOYABLE VEGETABLE PRODUCTION SYSTEM (VEGGIE) IN UNIT GRAVITY.   L.K. Tuominen, A.M. Rogney, and R.C. Morrow.  Orbital Technologies Corporation, Madison, Wisconsin.

   To minimize the need for resupply missions in accordance with an increasingly limited number of flight opportunities to the International Space Station, ORBITEC has developed a deployable vegetable production system (VEGGIE) that can be stowed in a small volume and deployed as a large growth system as needed.  While demonstration tests have shown the capability of the VEGGIE to grow a wide variety of vegetable crops and herbs, we also wished to clarify whether the system could produce biomass at levels consistent with hydroponic growth systems in unit gravity.

   Several growth trials of lettuce (Lactuca sativa cv. Grand Rapids) were conducted to determine the optimal fertilizer regime and root mat design as well as to compare growth in the VEGGIE to growth in an established hydroponic system.  Growth trials were also conducted for radish (Raphanus sativus) to establish optimal planting density and cultivar, although no comparisons to previously published growth systems were made.  Results for lettuce revealed that a looped mat design allowed for the best plant growth, with productivity as high as 8.0 g dry mass/m²/d in an early prototype mat and exceeding 5.4 g dm/m²/d in a flight-like prototype mat.  The latter productivity level approximated that observed in hydroponically-grown lettuce watered four times daily, but plants grown in VEGGIEs required watering on average only once every 3.8 d.  While VEGGIE-grown lettuce plants were on average smaller than those grown hydroponically, high planting densities were achievable in the mats without loss of growth uniformity, thus accounting for the similar productivity between the two systems.  Radish cultivar comparisons suggested that Cabernet radishes were the best of the available options for growth in VEGGIE mats; they produced on average 36.6 g edible fresh mass/m²/d over at a planting density of 16 plants per mat as compared to the 21.5 g edible fm/m²/d produced by the cultivar Champion.  Plant productivity in the VEGGIE is sufficiently close to that under hydroponic conditions to warrant its consideration as a means of supplementing crew meals on long-term missions.

   Supported by NASA SBIR Phase II Grant NNK04OA5C.