The final step in the rate calculation
What are the steps in calculating the photosynthetic rate (umole O2 / m2 / min) for a leaf that with an area of 0.0025 m2 and a O2 evolution rate of 0.096 %O2 / min?
Step 1) convert %O2 to uL O2/L
096 %O2 x 10,000 = 960 uL O2/L
Step 2) convert ÁL O2/L to Ámole O2/L
960 uL O2/L / [(273+23)/273) x 22.423] = 39.6 Ámole O2/L
Step 3) multiply by the volume of the leaf chamber
39.6 Ámole O2/L x 0.047 L = 1.86 Ámole O2 in the chamber
Step 4) divide by the area of the leaf. This expresses the rate per unit area, and allows direct comparison of rates even if leaves of different sizes are placed in the leaf chamber.
1.86 Ámole O2 / 0.0025 m2 = 744.0 umole O2 / m2 / min
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