ASGSB 1999 Annual Meeting Abstracts

10-DAY-TEST OF PESTO SCIENCE PROTOCOL IN THE BIOMASS PRODUCTION SYSTEM: A SUMMARY OF RESULTS. G.W. Stutte, O. Monje, G.D. Goins and D.K. Chapman. Dynamac Corporation, Kennedy Space Center, FL.

A 10-day-test of PESTO (Photosynthesis Experiment and System Testing and Operation) spaceflight mission procedures was conducted in the Biomass Production Chamber (BPS) Training Hardware. The BPS is a double middeck sized plant growth chamber being developed by Orbital Technologies for International Space Station (ISS) and Space Shuttle missions. The primary objective of the test was to determine whether the PESTO Science protocols for the BPS could be accomplished on-board the ISS. Each of the four BPS growth chambers was used to test different components of the PESTO protocol. Two chambers had plants of different starting ages (4 & 14 days old). Two chambers were used to determine whether pre-planted root modules could be stowed dry in the BPS and to measure germination percentage with on-orbit priming of the seed. The number of plants was sufficient to obtain gas exchange data from CO₂ drawdowns 9 days after priming dry seed. A discrepancy between actual and apparent moisture content in the root media resulted in reduced growth of the pre-established plants. However, apparent CO₂ flux rates of 6-7 mmol m^-2 s^-1 were obtained from plants 14-24 days old. CO₂ and PPF response curves were obtained at different stages of development. PPF response curves were linear (r2=0.9945) and the estimated light compensation point was 125 mmol m^-2 s^-1. High respiration rates resulted in CO₂ concentrations exceeding detector limits during the first 9 days of development. Transpiration rates of approximately 3.8 L m^-2 day^-1 were estimated from water additions to the plant root zone. Seed germination was 50% using the existing on-orbit priming procedures. Initial seed germination was not affected by dry stowage at 50% RH under high CO₂ or elevated ethylene concentrations.

(Supported by NASA: NCC10-0027).

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