[forgotpwtomain]

> C3 and C4 refer to different methods of photosynthesis. C4 confers advantages in sub optimal conditions - the most obvious form is growing in conditions of water stress.

It's been a while so I don't have a reference of the top of my head but [0] this is not correct. C4 plants will have better yield in any conditions where C3 plants reach light saturation - which applies to a lot of agricultural regions of central latitude.

[0] edit: Photosynthesis vs Irradiance graph from google images illustrating this: http://aciar.gov.au/files/mn-158/img/Figure_02.2.png