My primary interests are on photosynthesis, C-partitioning and productivity. Physiology and biochemical studies include, studying leaf photosynthesis and export. In addition, we are investigating CO2 and hydrocarbon exchanges of plants in sealed environments such as commercial greenhouses and specialized chambers being designed for the manned space program (Grodzinski 1992, Bioscience 42:517-525). We are also developing methods for the early detection of diseases in plants by using the plant as the sensor. For example, we are using photosynthesis, export and respiration profiles to monitor host/pathogen interactions. The Guelph team (SALSA, Space and Life Support Agriculture) of which I am a director works with Canadian greenhouse industries, the European Space Agency (ESA) and the Kennedy Space Centre (NASA). In the life support programs plants are viewed as essential machines for long-term missions because they are a sustainable food source, engines of gas exchange (CO2 scrubbing, O2 production) and water purifiers (leaf transpiration). A better understanding of natural ecotype variation, genetics and physiology of photosynthesis and productivity is fundamental to both the space program and the commercial greenhouse industry. Genetic approaches currently being pursued include modifying plants for better light interception. Candidate species are being selected for more efficient photosynthesis and growth at low light simplifying many constraints and limitation to hardware design in sealed environments. In all plantings reduced productivity results from mutual shading and low light.