CO2 greenhouse generators

Hi ,I am new here, And I just have this question about Biochar:
If Biochar secuestrates CO2 from the atmosphere, then stomata would have less CO2 available for photosynthesis. CO2 generators rise the level of CO2 inside greenhouses upto 1500 ppm to obtain maximun yields.
I see a contradiction here, because secuestrating atmospheric CO2 and taking it into the soil doesnt help the absortion of CO2 by the plant. (roots dont absorve. CO2; only leafes).
Can anybody explain me this please?, how biochar works in the CO2 metabolism of the plant?.

Bio-char is not used to make CO2 available to the plant through photosynthesis . There is a recognition that we have too much CO2 in the atmosphere creating Global Warming . The goal of using bio-char and also Hugelkulture is to sequester the carbon into the soil based web of life. Bio-char helps to hold H2O , prevents leaching of nutrients , binds contaminants , enhances fertility , elevates pH. There are quite a few posts on this forum showing great results using bio-char. Look around and welcome to permies.