Nine controlled-environment plant growth chambers will be utilized to provide the climate control necessary to conduct important studies in the area of plant physiology and biochemistry. Specific studies include the investigation of: 1) carbon metabolism in C3-C4 intermediate plants, 2) the regulation of photosynthesis at super-optimal light intensities, 3) the utility of stable carbon isotopes in studying the integration of the C3 and C4 photosynthetic pathways and 4) the regulation of fungal hyphae during the formation of parasitic or mutualistic relationships.