Ma, B. L. and Dwyer, L. M. 2012. Changes in kernel characteristics during grain filling in silage-specific and dual-purpose corn hybrids. Can. J. Plant Sci. 92: 427–439. Silage-specific corn (Zea mays L.) hybrids have been gaining in popularity in recent years, but there is a lack of information about the difference in kernel characterization between Leafy silage-specific and dual-purpose hybrids. A field study was conducted for 4 yr to determine the changes in kernel moisture content, kernel dry weight, kernel nitrogen (N) and phosphorus (P) concentrations over the period of grain filling for Leafy silage-specific and dual-purpose hybrids at two plant population densities. In both types of hybrids, kernel dry weight content increased rapidly from approximately 2 wk after silking and reached a maximum at about 50 to 68 d after silking. While some differences among hybrids in kernel maximum dry weight were noted (P<0.05), there was no distinction between hybrid types. The coefficients of kernel moisture change differed greatly between the two types with lower rates of decline of kernel moisture in some of the Leafy silage-specific hybrids (down-hill slope b<0.0136±0.00044 g kg^-1 d^-1) than the dual-purpose or silage hybrids without the Leafy characteristic (b≥0.0164±0.00039 g kg^-1 d^-1). Higher plant population density had a negligible effect on kernel moisture decline and N and P concentrations, but reduced kernel dry weight by up to 7% in one year. Kernel P was linearly positively correlated with N content (r>0.79, P<0.01), and there was a linear relationship between kernel moisture and the whole-plant silage moisture content (R²≥0.70). Our data also showed that one of the Leafy silage-specific hybrids had higher rates of kernel dry weight accumulation and softer kernel hardness (P<0.05) than the dual-purpose or non-Leafy silage hybrids. Our findings on the distinct characteristics of hybrid types are important considerations for corn producers to choose suitable hybrids and make decisions on silage harvest dates.