Determination of Evapotranspiration Rates for Wheat in Flight Hardware Mockup Microclimate

1
Determination of Evapotranspiration Rates for
Wheat in Flight Hardware Mock-up Microclimate

• Kimberly Beck
• SLSTP, Texas Womans University
• Jessica Prenger, Donna Rouzan-Wheeldon
• Dynamac Corporation
• Howard Levine, Ph.D., Principal Investigator
• NASA, Kennedy Space Center
• Tel [phone] Fax [phone]
• E-mail Howard.G.Levine_at_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.
2
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.

3
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 were measured to compare
  evapotranspiration rates with growth

Fig. 2. Experimental set-up of the flight
hardware mock-up inside a reach-in growth
chamber. Irrigation lines for the planted SC are
the black tubing on the right. Photograph by
Adam Santon.
4
Results
Fig. 3. Progress of plant growth over time (day
after planting (DAP)). Photographs by Jessica
Prenger and Kim Beck.
Fig. 4. Transpiration increased over time, and
the decrease in evaporation may be due to change
in relative humidity levels.
Fig. 5. Transpiration rates were directly
proportional to plant growth. A model of water
use for the compartments will be developed from
measurements of growth and microclimate.