The PIs will develop and test a miniature open-cell CO2 and H20 (MICAH) sensor that can be inserted into the leaf chamber of a plant gas exchange system or used in eddy-covariance measurements of canopy photosynthesis and transpiration. The MICAH sensor will be developed at the Space Dynamics Laboratory by the technical personnel that recently delivered similar sensors to NASA for use in space suits. This design will provide low- maintenance, battery-powered sensors connected to open-sided absorption cells using infrared transmitting fiber optics. Innovative miniature components and microprocessor control will provide high-resolution performance in a hand-held, flexible instrument. This sensor is an important improvement in technology for plant gas exchange because it will allow accurate measurements of non- steady-state photosynthesis. Measurements of this type are necessary in the study of plant responses to sunflecks, and have been limited by the design of current instruments. Because the sensor will allow analysis of CO2 concentration in the leaf chamber directly, it will also allow the development of a true CO2 porometer, which will improve the speed, accuracy, and portability of field gas exchange systems. Following the successful development of this sensor, a cost- sharing arrangement with NSF to make copies of it available to scientists whose research is limited by current sensor technology will proposed.
