Response to questions raised by Sinclair and Muchow

Concerns were raised by Sinclair, T.R., Muchow, R.C., 1999. [Occam's Razor, radiation-use efficiency, and vapor pressure deficit. Field Crops Res. Nn, in press] on the validity of the relationship between radiation-use efficiency (RUE) and vapor pressure deficit (VPD) for maize (Zen mays L.) and sorghum (Sorghum bicolor L. (Moench)) [Kiniry, J.R., Landivar, J.A., Witt, M., Gerik, T.J., Cavero, J., Wade, L.J., 1998. Radiation-use efficiency response to vapor pressure deficit for maize and sorghum. Field Crops Res. 56, 265-270]. This paper addresses these concerns and demonstrates how data by these authors compares with published response lines. Especially important are the different views on techniques of measuring intercepted radiation. I believe that adequate sampling to describe within-plot variability is more important than time of day effects when measuring radiation interception The published data from three studies are shown to agree closely with previously published response lines. Published by Elsevier Science B.V. All rights reserved.