Fig. 1. Relationship between kernel per apical ear and cumulative intercepted photosynthetically active radiation (CIPAR) during period bracketing silking (327°C days). Symbols indicate observed data, and curves indicate modeled response using Eq. [1] and [2] (see text for details). Observed data are from Tollenaar et al. (1992) for maize hybrids Pride, Pioneer 3978, and Pioneer 3851; from Iowa (Murrell and Childs, 2000) for Pioneer 34G82; and from Otegui and Bonhomme (1998) for six hybrids.