Determination of Evapotranspiration Rates for Wheat in Flight Hardware Mock-up Microclimate Kimberly Beck SLSTP, Texas Woman’s University Jessica Prenger, Donna Rouzan-Wheeldon Dynamac Corporation Howard Levine, Ph.D., Principal Investigator NASA, Kennedy Space Center Tel: 321-861-3502 Fax: 321-861-3502 E-mail: Howard.G.Levine@nasa.gov Fig.1. Kimberly Beck, a 2004 SLSTP student, setting up the experiment in a reach-in growth chamber at the SLS lab. Photograph by Adam Santone. Background This experiment was part of ground research activity with the Water Offset Nutrient Delivery ExpeRiment (WONDER), a mid-deck Space Shuttle payload investigating crop production for fresh food and advanced life support. Evaporation and transpiration rates were measured for wheat grown in a flight hardware type substrate compartment and environment. Data about water use and growth rates will be used to develop irrigation control systems for the WONDER flight experiment. Methods • 15 wheat seedlings were planted in a substrate compartment (SC) with granular media and a porous tube for nutrient delivery • SCs were placed in a mock-up flight hardware environment: 1) with plants (measuring evapotranspiration), 2) no plants (measuring evaporation) (figure 2) • SC water balance measured evaporation, evapotranspiration, and irrigation rates; plant heights Fig. 2. Experimental set-up of the flight were measured to compare hardware mock-up inside a reach-in evapotranspiration rates with growth chamber. Irrigation lines for the planted SC are the black tubing on the growth right. Photograph by Adam Santon. Results DAP 5 DAP 10 DAP 15 DAP 18 DAP 24 Fig. 3. Progress of plant growth over time (day after planting (DAP)). Photographs by Jessica Prenger and Kim Beck. 12 16 10 Change in mass (mL per day per plant) Transpiration (mL per day per plant) 14 Evaportranspiration WOND 04 08 R2 = 0.9034 8 Evaporation 12 6 10 4 8 2 6 0 4 -2 2 -4 0 -6 0 5 10 15 20 25 0 50 100 150 200 250 300 350 DAP (day) Avg Growth (mm) Fig. 4. Transpiration increased over time, and the Fig. 5. Transpiration rates were directly proportional decrease in evaporation may be due to change in to plant growth. A model of water use for the relative humidity levels. compartments will be developed from measurements of growth and microclimate.
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