ASGSB 1998 Annual Meeting Abstracts

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SENSITIVITY OF LETTUCE AND WHEAT SEEDLINGS TO VARIOUS SURFACTANTS. S. Thompson¹ and J. Garland². ¹Florida A & M University, Tallahassee, Florida. ²Dynamac Corporation, Kennedy Space Center, FL.

The amount of water and other required resources cannot be stored on long-duration space flights due to limited space. High costs make resupplying the crew undesirable. A potential alternative is using an Advanced Life Support system to recover and recycle resources. Direct recycling of gray water through a plant growth hydroponic hydroponic system minimizes the need for a bioreactor. However, plants exhibit phytotoxic effects due to surfactants in gray water. The aim of this study was to identify a surfactant that caused minimal to no phytotoxic effects. The surfactants were selected based on ionic content: potassium (K-based mug soap), sodium (Ivory®), sulfate and sodium (Igepon®). It was believed that all the surfactants were equally toxic, but the best surfactant was sodium and/or sulfate free. The degree of lettuce and wheat sensitivity to toxicity tests was investigated. To determine which surfactant had the least effect on growth, seeds were placed on Petri dishes containing solutions of various surfactants at different concentrations. Effects on growth were compared using percent germination, average root length, and percent growth reduction. Average root length of wheat was less affected by K-based solution at 1000mg/L than lettuce. Lettuce exhibited a growth reduction of 80% in K-based solution, while wheat growth was reduced by 30%. Comparison of dosage curve trends showed that lettuce was more sensitive and that K-based mug soap was the best surfactant. (Supported by the NASA Space Life Sciences Training Program)

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