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The production of essential commodities (O2, H2 O, and edible biomass) and removal of CO2 by higher plants in bioregenerative life support systems would be seriously limited by the occurrence of disease epidemics. Among several treatment possibilities is ultraviolet (UV) radiation, which is one of the preferred sterilization techniques due to cost considerations and observed effectiveness against pathogens in hydroponic systems. Doses of 20 to 40 mW.s/cm2 as estimated in a laboratory flowthrough apparatus inactivated 99.99% of Pythium aphanidermatum, a common pathogen of hydroponic crops. Inactivation increased logarithmically with UV radiation dose. NCER (Net Carbon Exchange Rate) provides an indirect method to determine the effectiveness of UV in reducing Pythium infection, by measuring any changes in primary plant productivity.

The occurrence of disease epidemics in bioregenerative life support systems would seriously limit the production of essential life support requirements. The capacity of diseased plants in closed environment chambers to scrub CO2 was studied with lettuce plants infected with a common greenhouse pathogen, Pythium.At harvest, infected lettuce showed less edible biomass, decreased leaf area, and reduced photosynthesis averaging 50% on a per chamber basis. These results and others are discussed to show the potential of using existing instrumentation in life support systems to monitor the health of the plant canopy, predicting early onset of disease and refining remediation strategies.