Occam's Razor, radiation-use efficiency, and vapor pressure deficit

Occam's Razor dictates that the hypothesis with the fewest assumptions in e xplaining the results is preferred. In a recent paper by Kiniry et al, (Fie ld Crops Res. 56, 265-270, 1998), Occam's Razor was overlooked in favor of a hypothetical relationship of decreasing radiation use efficiency (RUE) wi th increasing vapor pressure deficit (VPD). Their conclusion is challenged for three reasons. Firstly, there is virtually no background information th at supports such a relationship. Secondly, no rigorous test of the data of Kiniry et al. was presented to confirm such a conclusion over the hypothesi s that RUE was not sensitive to VPD. Thirdly, there are concerns in the met hods used to experimentally estimate VPD and RUE. (C) 1999 Elsevier Science B.V. All rights reserved.