Light Response Curves

Light response curves measure plant response(s) to light intensity. These measurements explore the difference in Rd (dark respiration rate), ΦCO2, maximum apparent quantum efficiency, Asat (light saturated photosynthesis) and light compensation point (the light level at which photosynthesis equals respiration). Click here for more information on how the LI-6400XT controls light.

Light response graph

Figure of the photosynthetic response to increasing absorbed light (αPAR). Glycine max (soybean) leaf was excised from experimental-garden grown plant and then light acclimated at 1400 µmol m-2 s-1 (saturating) in 385 µmol CO2 mol-1air. The incident light was corrected to account for absorption (93%) of the light-source wavelengths. Experimental data (circles) were fit (cyan line) using a nonrectangular empirical function to estimate the light saturated rate of photosynthesis at growth CO2 (Asat, see Long and Hällgren, 1993). The 95% confidence intervals for the regression are plotted (black line).


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