Demetriades-Shah et al. (Agric. For. Meteorol., 1992, 58: 193-207) cast doubts on (a) the dependence of crop growth on incident solar radiation under 'normal' field conditions; (b) the validity of the relation between crop growth and intercepted radiation; (c) the need to measure interception as distinct from estimating plausible values. A review of relevant field evidence suggests that most of these doubts are insubstantial.