Fig. 3. Response of kernel set in the apical ear (E₁) of four hybrids (AP162, AP9191, DK664, and DK752) to (a) the number of pollen grains per square centimeter registered on the date of silking of individual plants (plants were grouped by silking date), and (b) the cumulative number of pollen grains received per silk exposed from the apical ear. For each hybrid, kernel number of plants with the same silking date was averaged and values referred to the maximum average for computing kernel set. The equations correspond to the model fitted in each figure. In panel (a), the model was fitted exclusively to late-silking plants of the American hybrids (AP162 and AP9191) and do not include symbols in brackets from the Argentine hybrids (DK664 and DK752).