Metabolic Rate Processes of Plants

2011-13 New Investigator Award

Michael Bender’s project centers around the development of a high-precision method for measuring plant photosynthesis and respiration rates in the light under controlled conditions, and the use of this method to investigate fundamental topics in plant physiology. These include measuring rates of photosynthesis as a function of irradiance, measuring changes in respiration rate as a function of irradiance, examining the relationship between respiration and photorespiration rates, and looking at the influence of nitrate uptake on respiration.

These measurements will be enabled by methods involving isotopes and high precision mass spectrometry developed in Bender’s laboratory over many years. They also rely on the Picarro cavity ringdown spectrometer, a state-of-the-art instrument purchased in part with Siebel Energy Challenge funds that measures the CO2 concentration of air, and the isotopic composition of CO2, at high precision.

The results will address basic questions in plant physiology and will improve our ability to assess the response of plants to increasing CO2 concentrations in air.

Educational Impacts

Since August of 2011, the cavity ringdown spectrometer has been used to semi-continuously measure the CO2 concentration of air and the carbon isotope composition of the CO2. The air intake is on the roof of Guyot Hall, and is visible from the west side of the building. The data were first used in a successful GEO 102 laboratory in the fall of 2011. Even with a data set of only four months, students were able to begin assessing the magnitude of seasonal changes in the CO2concentration of air (it rises after summertime because it is released by rotting vegetation), the daily cycle of CO2 (it goes up at night, when vertical mixing of the lower atmosphere is slow), and the carbon isotope composition of respired CO2 (a way to distinguish between basic vegetation types in the region). Opportunities to use these data, both in GEO 102 and other courses, will increase and be encouraged in the coming semesters.

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Professor of Geosciences

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