MadSci Network: Botany |
I am not sure this has ever been measured. There are a large number of variables, such as temperature, solar intensity, fertility. Of the places I have looked I did not find anything I would consider a reasonable answer.
If you have a horticultural or agronomic department in a local college you might contact them, and set up a procedure to test and measure what you are looking for (It sounds like a Master Project).
I am making contacts some professional society members to see if someone in London can help out.
Please keep in contact as I will come up with something that should help, it just may take a little time.
Dale Softley
Forensic Agronomist / Certified Professional Agronomist
Lincoln, NE
Try the links in the MadSci Library for more information on Botany.