So I have been looking for any reliable information on the relationship between temperature and CO2. Being a soil chemist, I have looked for any technical papers on the subject. I found one vary interesting article here: http://www.springerlink.com/content/a3527u6018823x43/ For those of you unable to see the full article, here is the basic summation: "In view of our results, it is concluded that C. sativa can utilize a fairly high level of PPFD and temperature for its gas and water exchange processes, and can perform much better if grown at ~ 1500 μmol m-2 s-1 PPFD and around 25 to 30 oC temperature conditions. Furthermore, higher PN, WUE and nearly constant Ci/Ca ratio under elevated CO2 concentration, reflects its potential for improved growth and productivity in drier and CO2 rich environment." -Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions Suman Chandra1, Hemant Lata1, Ikhlas A. Khan1,2 and Mahmoud A. Elsohly PPFD is also known as photon flux density. A simple conversion is 1 unit of PPFD equates to about .22 W per square meter. They also stated that the optimum CO2 concentration at this range is 750 PPM. They did not test higher levels of CO2, which is really what I am looking for. (the 1500 ppm range). It would be interesting to see these types of results. The paper also finds that with the doubling of atmospheric CO2 concentrations, from 280 ppm to above 600 ppm, suppresses transpiration and conductance. At the same time, photosynthesis, water use efficiency and intracellular concentration of CO2 increased. Maybe a little too much info, but it is probably safe to assume that keeping down humidity, keeping temps below 87 F and having a high ppm of CO2 would greatly increase the plants yield. Go Tigers!