Evapotranspiration and Photosynthesis Characteristics of Two Wheat Cultivars Measured in the Biomass Production System 2001-01-2180

A 24-day test of the science protocols for the PESTO (Photosynthesis Experiment System Testing and Operation) experiment was conducted in the Biomass Production System (BPS) flight hardware. One objective of these experiments was to identify the optimum times during the life cycle for characterizing canopy level evapotranspiration and photosynthesis under closed atmosphere conditions in the BPS. Carbon dioxide and light response curves were obtained at three stages of development on two dwarf wheat cultivars, Apogee and Super Dwarf. Net daily carbon assimilation rates were derived from CO₂ additions to each chamber and the relative growth rate of each cultivar was determined. Evapotranspiration rates were derived from water additions to the rooting matrix through the nutrient delivery system and water vapor removal from the atmosphere though the humidity control system. The effects of short-term changes in vapor pressure deficit (VPD) on evapotranspiration rates was determined on a full canopy of Super Dwarf during programmed changes in BPS temperature and relative humidity setpoints. (Supported by NASA’s Fundamental Biology Program through NCC-0027).