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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Rangeland Resources & Systems Research » Research » Publications at this Location » Publication #358618

Research Project: Improved Management to Balance Production and Conservation in Great Plains Rangelands

Location: Rangeland Resources & Systems Research

Title: Factors influencing the measurement of assimilation and stomatal conductance with the LI-COR 6400XT gas exchange system

item Lecain, Daniel
item Gleason, Sean

Submitted to: bioRxiv
Publication Type: Trade Journal
Publication Acceptance Date: 12/12/2019
Publication Date: 12/12/2019
Citation: Lecain, D.R., Gleason, S.M. 2019. Quantifying experimental error in the measurement of assimilation and stomatal conductance with the LI-COR 6400XT gas exchange system. bioRxiv.

Interpretive Summary: This experiment investigated sources of experimental error in measuring photosynthesis and stomatal conductance with modern plant “gas-exchange” equipment. Multiple sources of experimental error were found and quantified and suggestions are made for improving the dependability of these types of measurements.

Technical Abstract: Although CO2 and H2O exchange rates are often measured in experiments as indicators of physiological plant responses these “gas exchange” measurements are prone to large experimental error. Gas exchange equipment and technology have improved greatly over the past two decades which supports scrutinizing current issues of experimental error in measuring plant photosynthesis and stomatal conductance. This report shows results of a greenhouse experiment with the goal of identifying lessor understood sources of experimental error and variation in measurements with the LI-COR 6400XT gas exchange system. A variety of plant types were used to encompass differing species variation. We found significant sources of experimental error in 1) the time for initial adjustment when placing a leaf in the leaf chamber 2) the time-of-day when measuring 3) leaf age 4) having the chamber window full vs. partially full with leaf tissue 5) using a leaf chamber environment that greatly diverges from the whole plant environment 6) differing degree of experimental error depending upon plant species. A situation with multiple contributors to error would result in useless gas-exchange data. Recommendations for minimizing these experimental errors are given.