Fig. 10. Dependence of grain yield and kernels per plant on pollen availability per silk. Differences in total pollen production per ha across treatments were normalized to the total number of emerged silks per hectare. This calculation assumes each plant produces the average number of silks for the hybrid, and second ears (when present) produced an equal number of silks. Average silks per ear for P3978 = 670, and for P3925 = 607. Note that yield and kernel number decrease at pollen densities less than 3000 pollen grains per silk.