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

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.

Plant phenotyping relevance

LI-CORガス交換システムによる光合成・気孔コンダクタンス測定の誤差要因を実験的に検証し、測定改善策を提示しており、植物表現型取得法が中心である。

Code and data availability

The supplied blocks contain no data availability statement, no public phenotype dataset, no author code/scripts, and no supplementary assets. The paper describes LI-COR 6400XT gas-exchange measurements and figures, but no public repository or deposit of the underlying measurements is mentioned.

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