Hey Aqua thanks for the oxygen rhizosphere study - been a good read!
btw - roots can absorb CO2/bicarbonates and they have a metabolic pathway to process that, some even seems to enter starch production in the leaves. BUT... I'm not able to find anything on this on cannabis and believe the amount is rather small, though in
C4/CAD/CAM plants it seems to matter a bit.
Maybe one day we'll know more about how to make use of this. As for now, atmospherical CO2 levels still rise so hemp will perform better with each year xD (and hopefully help to
remedy our biosphere!)