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EVAPOTRANSPIRATION AND WATER USE OF PLANT STANDS IN MICROGRAVITY. O. Monje and G.W. Stutte.  Dynamac Corp., Mail Code DYN-3, Kennedy Space Center, FL.

   The future exploration of space will require a fundamental understanding of how living organisms respond to prolonged exposures to microgravity. This understanding will enable scientists, engineers, and planners to design future missions and spaceflight hardware using results from long-term experiments in microgravity conducted on ISS. An objective of the PESTO flight experiment was to determine if microgravity affects whole-stand evapotranspiration of wheat in microgravity. Measuring the rates of water use by fast growing plants in these systems in space and determining if water use is affected by microgravity can lead to improved designs of water delivery hardware, humidity and rootzone moisture control algorithms for future payloads. Canopy evapotranspiration rates were measured nondestructively in microgravity during several replicate plantings and compared with ground controls. The cumulative amount of water used by flight (n=4) and ground (n=5) plant stands was not significantly different in microgravity. Similarly, canopy evapotranspiration was not significantly different in microgravity, however, a trend exists for evapotranspiration to be slightly lower in flight after 10 DAP. This trend may be related to differences in light penetration into the canopy caused by different leaf areas between the flight and ground plants.

(This research was supported by grant from NASA OBPR Fundamental Biology Programs (NCC10-0027))