Fig. 1.

Regional climate and development. Midwestern US maize develops through vegetative (green), early grain-filling (blue), and late grain-filling (cyan) growth phases beginning as early as April and ending as late as October. Also shown is the climatology of GDDs (orange) and KDDs (red) over the growing season after smoothing with a 30-d window for purposes of clarity. KDDs are shifted upward such that 0 KDDs and 8 GDDs are level. Light shading indicates the earliest decade in the analysis (1981–1990) and dark the latest (2008–2017), where more recent growing seasons begin earlier and end later, have lower KDD exposure, and have higher GDD exposure related to longer maturation.