I apologize for being too negative about the tobacco, you are absolutely right. The paper concludes that it is hopeful for improving grain crop yields: > We ar

I apologize for being too negative about the tobacco, you are absolutely right. The paper concludes that it is hopeful for improving grain crop yields: > We are optimistic that similar gains may be achieved and translated into increased yield in C3 grain crops because photorespiration is common to all C3 plants and higher photosynthetic rates under elevated CO2, which suppresses photorespiration and increases harvestable yield in C3 crops. However, does not refute the other papers I have linked about C3/C4/CAM photosynthesis that suggest that C4 may not be universally beneficial, but an optimization in certain contexts only. I do hope enhancements to plants in agroforestry settings, or restorative agricultural practices in general, are also possible. Those are badly needed if we want to regenerate topsoil and perhaps even make food production a net carbon-sink.