Response of Plant Water Status to Reduced Atmospheric Pressure

Increased fascination with planetary exploration has stimulated the expansion of advanced life support studies focused on complete resource recycling. Essential for the proper functioning of a reduced pressure, Martian based, bioregenerative life support system is a complete understanding of plant water status and related plant physiology under hypobaric conditions. Reduced pressure studies at the Controlled Environment Systems Research Facility at the University of Guelph, Canada have measured and derived an empirical correction factor for the effect of pressure on the in situ stem psychrometer. This technique allows for the accurate assessment of plant water potential under reduced pressure conditions. Transpiration was measured gravimetrically and water potential was assessed using the in situ stem psychrometer, which was then corrected for the effect of both temperature and pressure. The calibration of the in situ stem psychrometer, empirical correction factor for pressure, and preliminary results will be discussed.