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Title: Calculating photosynthetic rate with light and dark CO2 analyses Post by: AlaskaCaspar on Sep 14, 2016 Hi everyone,
I recently did a lab where we measured CO2 levels using a Qubit system. We took a reference CO2 level without a leave in the leaf chamber, then a steady CO2 level with a leaf in the leaf chamber and the light turned on, and lastly a steady CO2 level with the leaf in the leaf chamber and the light turned off. The CO2 level in the light went below the reference CO2 level and the dark analysis CO2 level went up above the reference CO2 level. I understand that when the light CO2 level went down the plant was photosynthesizing and when the dark CO2 level went up it was because the plant was respiring. What I'm having difficulty understanding is how to calculate the rate of photosynthesis. Our lab asked us to calculate the CO2 exchange rate using the light analysis CO2 level and the reference CO2 level, which I would've thought was rate of photosynthesis, but the manual says that's wrong and that the dark analysis CO2 level is needed for some kind of correction. How is the CO2 exchange rate not the rate of photosynthesis and how is the dark analysis CO2 level used to calculate it? Thanks for any help anyone might be able to offer. My searches have all made it sound like the CO2 exchange rate is the rate of photosynthesis. Title: Re: Calculating photosynthetic rate with light and dark CO2 analyses Post by: bio_man on Sep 15, 2016 Can't you calculate the slope?
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